HE EXTERIOR OE THE HORSE LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Class THE EXTERIOR OF THE HORSE BY ARMAND GOUBAUX, AND GUSTAVE BARRIER, U HONORARY DIRECTOR OF THE VETERINARY SCHOOL OF ALFORT, MEMBER OF THE ACADEMY OF MKD1CINE AND OF THE NATIONAL SOCIETY OF AGRICULTURE OF FRANCE, PROFESSOR OF ANATOMY AND THE EXTERIOR, AT THE VETERINARY SCHOOL AT ALFORT, MEMBER OF THE CENTRAL SOCIETY OF VETERINARY MEDICINE OF FRANCE. SECOND EDITION, With 346 Figures and 34 Plates, by G. Nicolet, LIBRARIAN AT THE VETERINARY SCHOOL OF ALFORT. TRANSLATED AND EDITED BY SIMON J. J. HARGER, V. M. D., PROFESSOR OF ANATOMY AND ZOOTKCHNICS IN THE VETERINARY DEPARTMENT OF THE UNIVERSITY OF PENNSYLVANIA. LIPPINCOTT OMPANY' PHILADELPHIA: J. B. LIPPINCOTT COMPANY. LONDON. 10 HENRIETTA STREET, COVENT GARDEN. 1892. Copyright, 1892, by J. B. LIPPINCOTT COMPANY. PRINTED BY J. B. LIPPINCOTT COMPANY, PHILADELPHIA, U.S.A. TO THE MEMBERS OF THE VETERINARY PROFESSION, AND ALL CONNOISSEURS OF THE HORSE, THIS WORK IS DEDICATED BY THE TRANSLATOR. PREFACE BY THE TRANSLATOR. PROGRESS in veterinary science implies advance in investigation and the publication of books setting forth the results of that advance. Numerous volumes of veterinary literature have of late years appeared from the pens of both French and German writers ; but in English there has been very little produced upon the subject ; and English- speaking teachers, practitioners, and students constantly find themselves compelled to look to foreign writers for instruction on points connected with their vocation. In no branch of this literature has this deficiency been more seri- ously felt than in that which studies the horse exclusively from the exterior, considering his external form and characters with relation to his mechanical aptitude and his commercial value. Hence I was in- duced to fill this vacancy by the translation of Goubaux and Barrier's " Exterior of the Horse." In selecting this book, the French veterinary text-book par excel- lence, I was influenced no less by the reputation and standing of its authors than by the originality, exactness, and fulness of its treatment of the subject. The difficulty of such an undertaking can be fully appreciated only through actual experience. I have endeavored as far as possible to avoid the use of French terms. In some instances, however, it was impossible to find English terms that would convey the exact mean- ing of the terms of the original text. Wherever I have retained the foreign terms, it has been done solely for the sake of brevity and simplicity. No pains have been spared to make this one of the most complete books of its kind. The numerous plates and figures thoroughly elu- cidate the more difficult points of the text ; and references are made to all the best French, German, and Italian treatises on the veterinary science. One of my special aims has been to adapt this book to the English-speaking reader. It contains valuable information for the practitioner, the student, the horseman, and the breeder. vi PREFACE BY THE TRANSLATOR. I take occasion here to acknowledge my obligation to M. Barrier and Messrs. Asselin and Houzeau for the loan of the plates and cliches, and also to express my gratitude to the friends who have assisted me in my work, and particularly to the publishers for their generous as- sistance, for the ability with which they have executed their portion of the undertaking, and for the interest they have manifested not only in this work, but also in all publications pertaining to veterinary science. Nor must I forget, finally, to express my obligations to Mr. E. R. Jones for his conscientious care in reading and correcting the proof. SIMON J. J. HARGER. 205 NORTH TWENTIETH STREET, PHILADELPHIA, December 3, 1891. PREFACE TO THE FIRST EDITION. IN the preparation of the work herewith offered to the public, our aim has been to select from the science which treats of the rational improvement of domestic animals the science of zootechnics that chapter which bears upon the consideration of the external forms and the characteristics of the horse in their connection with his mechanical aptitudes and, his commercial value. This study, for which we have retained the name given to it by the founder of veterinary schools, merits a treatment very different from the theoretical and empirical one accorded to it by the majority of our predecessors. We have endeavored, therefore, on all important points, to base our opinions upon numerous careful researches pursued by ourselves in person ; and from these data we have deduced, or by them confirmed, the principles of a judicious appreciation of the physical and moral qualities of the horse. To our teaching colleagues, our associates, our pupils, and all others who have aided us in our task, we here acknowledge our deep gratitude. If we have not cited the names and treatises of all the authors who have written upon the exterior of the horse, it is because we had de- termined, in the matter of bibliography and out of consideration for our readers, to abstain from all idle discussions and uninteresting controversies. As for the rest, we think we have done them full justice in the numerous citations we have made from their works. Our labors have been singularly facilitated by the friendly interest and generosity of our publishers, who will allow nothing to stand in the way of the successful completion of a book useful to science, and, in particular, of one useful to the veterinarian. We are indebted atao to M. G. Nicolet, librarian to the veterinary school of Alfort, whose artistic skill has reproduced, among other sub- jects, with an exactness hitherto unknown in works of this kind, the characteristics of the dental wear, the recognition of which is a matter of such great importance in determining the age. ARMAND GOUBAUX, GUSTAVE BARRIER. ALFORT, March 15, 1884. vii PREFACE TO THE SECOND EDITION. THIS second edition, in preparation for three years, has been the subject of a careful revision and of numerous alterations. Some very notable improvements upon the first edition have been made. A new plate upon the age, and fifty-three original figures, have been added. The matter, while much condensed as a whole, has in many places been rewritten at great length. Finally, by the employment of three varieties of type, we are enabled to indicate the degree of importance of each subject treated, and to facilitate the use of the volume to those who can consult only the essential parts. ARMAND GOUBAUX, GUSTAVE BARRIER. ALFORT, March 1, 1890. IX CONTENTS. SECTION FIRST. PRELIMINARY IDEAS OF ANIMAL MECHANICS. CHAPTEK I. PAGE OBJECT, END, AND UTILITY OF THE EXTERIOR 1 CHAPTEK II. CENTRE or GRAVITY 8 CHAPTER III. THE LEVER AND MUSCULAR MECHANISM 11 CHAPTEK IV. THE INCLINED PLANE . , 19 SECTION SECOND. STUDY OF THE REGIONS. \ 1. DIVISIONS OF THE HORSE 21 \ 2. SOME DEFINITIONS 31 A. Beauties 31 B. Defects 32 C. Blemishes 32 D. Vices and Faults 33 F>A RT I. THE HEAD. CHAPTER I. ANTERIOR FACE .- 36 A. The Forehead 36 B. The Face 38 C. Extremity of the Nose 40 xi xii CONTENTS. CHAPTER II. LATERAL FACES 41 A. The Ear ' 41 B. The Temple 46 C. The Supra-orbit and the Eyebrows 47 D. The Eye 48 E. The Cheek 58 F. The Nostrils 59 CHAPTER III. POSTERIOR FACE 65 A. Intermaxillary Space 65 B. Inferior Maxillary Region 67 C. The Chin . . . 68 CHAPTER IV. INFERIOR EXTREMITY 69 A. The Mouth and its Subdivision 69 1. The Lips 69 "2. The Teeth and the Gums 73 3. The Bars 74 4. The Lingual Canal 75 5. The Tongue * . . . 76 6. The Palate 79 B. The Mouth in General 79 CHAPTER V. POSTERIOR EXTREMITY 82 A. The Poll or Nape 83 B. The Parotid Region 83 C. The Throat 85 CHAPTER VI. HEAD IN GENERAL 85 A. Harmonibus Relations 86 B. Length - 8 ? C. Volume 87 D. Direction E. Forms F. Attachments 95 G. Movements 95 H. Expression 96 F>ART II. THE BODY. CHAPTER I. SUPERIOR FACE .'.... 98 A. The Neck 98 The Mane and the Forelock ..,.... 109 CONTENTS. xiii PAGE B. The Withers Ill C. The Back 116 D. The Loins 122 E. The Croup 123 The Haunch , 142 CHAPTEK II. ANTERIOR EXTREMITY 144 A. The Breast, or Pectoral Kegion 144 B. The Inter-axilla 147 C. The Axilla 147 CHAPTEK III. INFERIOR FACE 148 A. The Xiphoid Region 148 B. The Ahdomen 149 CHAPTER IV. LATERAL FACES 152 A. The Costal Region ; Rihs ; Sides 152 The Chest in General 157 B. The Flank . 162 C. The Groin 167 CHAPTER V. POSTERIOR EXTREMITY 168 A. The Tail 168 B. The Anus 174 C. The Perineum and the Median Raphe 175 CHAPTER VI. GENITAL ORGANS 176 \ 1. Genital Organs of the Male 176 A. The Testicles and their Envelopes 176 B. The Sheath and the Penis 181 $ 2. Genital Organs of the Female 184 A. The Vulva , 184 B. The Mammae 186 F> A RT III. THE MEMBERS. GENERAL CONSIDERATIONS 186 1. Action of the Anterior Member 196 2. Action of the Posterior Member 198 CHAPTER I. ANTERIOR MEMBER 200 A. The Shoulder 201 B. The Arm . . 214 XIV CONTENTS. PAGE C. The Elbow 219 D. The Forearm 221 E. The Chestnuts 227 F. The Knee 227 CHAPTER II. POSTERIOR MEMBER 237 A. The Thigh and the Buttock 237 B. The Stifle 244 C. The Leg , .... 246 D. The Hock 253 E. The Chestnut 279 F. The Canon and the Tendons 279 G. The Fetlock 290 H. The Footlock and the Ergot . . 297 I. The Pastern 298 J. The Coronet 309 CHAPTER III. THE FOOT 312 A. Organization 312 1. Internal Parts 313 2. The Hoof 316 B. Properties and Mechanism 322 C. Beauties 327 D. Defects 328 1. Of Volume and of Proportion 328 2. Of Conformation 329 3. Of the Axis 332 4. Of Quality of the Horn 334 E. Accidents occasioned by Shoeing 335 F. Diseases . 336 SECTION THIRD. PROPORTIONS. PART I. INTRODUCTION. CHAPTER I. PRELIMINARY IDEAS 341 CHAPTER II. HISTORICAL . 344 CONTENTS. XV II. OBJECT AND UTILITY OF THE PROPORTIONS. CHAPTEK I. PAGE POINTS OF VIEW FROM WHICH THE PROPORTIONS ARE STUDIED . . . _. . . 357 A. Kelation of Dimensions between the Parts ......... .... 358 B. Angular Relations of the Osseous Segments ............. 365 Theory of the Similitude of the Angles and the Parallelism of the Bony Segments ....................... 365 C. General Relations of the Ensemble, the Whole Organism ...... 385 D. Relations of the Organism with the Nervous System ......... 397 CHAPTER II. ISOLATED EFFECTS OF BEAUTIFUL PROPORTIONS UPON THE ANIMAL MA- CHINE .................... ..... . . 404 A. Conditions of the Motor en Mode de Masse, or of Force ....... 405 B. Conditions of the Motor en Mode de Vitesse, or of Speed ...... 407 C. Conditions of the Mixed Motor. (Combination of Force and Speed realized ) .......................... . 408 D. Excitability ; Impressionability ; Irritability ............ 410 CHAPTER III. RESULT OF BEAUTIFUL PROPORTIONS UPON THE ANIMAL MACHINE . . . 412 Resistance to Fatigue : Endurance . ................. 412 CHAPTER IV. DEFINITIVE SYNTHESIS .... . 429 ' SECTION FOURTH. THE HORSE IN RELATION TO LOCOMOTION. PART I. ATTITUDES AND MOVEMENTS UPON PLACE. CHAPTER I. ATTITUDES 438 A. Station 438 Axes, Equilibrium 442 a. Of the Anterior Members 443 b. Of the Posterior Members 456 B. Lying Down or Decubitus 466 xvi CONTENTS. CHAPTER II. MOVEMENTS UPON PLACE 468 A. Hearing 468 B. Kicking 470 PART II. MODE OF PROGRESSION, OR THE GAITS OF THE HORSE. CHAPTEK I. GENERALITIES OF THE GAITS 472 ANALYSIS OF THE GAITS 479 Systems of Notation of the Gaits 490 SYNTHETIC STUDY OF THE MODE OF PROGRESSION . 496 CHAPTER II. THE GAITS IN PARTICULAR 503 A. The Amble, Pacing 504 Broken Amble 509 B. The Trot 510 Broken Trot, Flying Trot : 522 Racking 522 Skipping 527 The Canter 527 Running Walk 529 C. The Walk 530 Backing 542 D. The Gallop 544 E. Leaping 569 Bounding and Bucking 575 CHAPTER III. DEFECTS IN THE GAITS 576 A. Defects existing in the Anterior Members alone 577 1. Dragging the Toe , 577 2. Excessive Knee-Action 578 3. Immobilized or Pegged Shoulders 578 B. Defects existing in the Posterior Members alone 57$ 1. String-halt 579 2. Rotating Hocks 581 C. Defects dependent upon the Mode of Association in raising the Ante- rior Feet and resting the Posterior 582 Forging 582 D. Defects existing separately or simultaneously in the Anterior or the Posterior Members 584 1. Rocking 584 2. Strain of the Loins 585 B. Defects existing indiscriminately in the Four Members . ; 586 1. Billarder, Paddling 586 2. Interfering 586 3. Lameness 588 CONTENTS. xvii SECTION FIFTH. AGE OF THE HORSE. PART I. THE TEETH. CHAPTEK I. PAGK THE INCISORS 597 A. Of the First Dentition 597 B. Of the Second Dentition 601 C. Structure 606 D. Details of the Dental Table according to the Age 615 E. Direction 616 The Tusks or Canine Teeth 619 CHAPTER II. THE MOLARS 621 1. Supplementary Premolars 621 2. Molars Proper 622 A. Of the First Dentition 622 B. Of the Second Dentition 625 C. Development and Structure . 631 CHAPTER III. ERUPTION OF THE TEETH 637 A. Of the Incisors 637 B. Of the Canines 640 C. Of the Molars . . 640 PART II. DETERMINATION OF THE AGE. CHAPTER I. DURATION OF LIFE IN THE HORSE 642 CHAPTER II. THE PARTS TO BE EXAMINED FOR THE DETERMINATION OF THE AGE . . 645 CHAPTER III. THE CHARACTERS FURNISHED BY THE TEETH , . . , . 643 B xviii CONTENTS. F>A RT III. PAGE IRREGULARITIES OF THE DENTAL APPARATUS 721 1. Number , 721 2. Form 726 3. Union of Two Teeth 726 4. Form of the Central Enamel 727 5. Depth of the Infundibulum and its External Dental Cavity 729 6. Defect of Length or Excess of Width of one of the Jaws 736 7. Excessive or Insufficient Wear 738 8. Wear resulting from Cribbing 752 9. Employment of Fraudulent Mean's 762 SECTION SIXTH. CONSIDERATIONS RELATIVE TO THE DESCRIPTION AND IDENTIFICATION OF THE HORSE . . 771 CHAPTER I. THE COATS 771 1. Coats properly so called 771 \ 1. Primitive Coats 773 A. Simple Coats (Black, Sorrel) 773 B. Composite Coats (Isabella Bay, Mouse-Color) 775 C. Mixed Coats (Fox-Color) 777 \ 2. Derived Coats (Gray, White, Flea-bitten, Roan) 778 \ 3. Conjugate Coats (Piebald, Conjugate, Isabella) . . . 782 Spotted or Marbled Coats 784 Synoptical Table of the Coats 784 2. Peculiarities of the Coats 785 A. General 786 B. Of the Head 794 C. Of the Body 796 D. Of the Members 797 Synoptical Table of the Peculiarities of the Coats 800 3. Causes of the Modifications of the Coats 799 4. Indices furnished by the Coats and their Peculiarities as to the Qualities of Horses 803 CHAPTER II. THE HEIGHT 806 CHAPTER III. CERTIFICATE OF DESCRIPTION - - 813 CONTENTS. xix SECTION SEVENTH. THE APTITUDES OR THE SERVICES. CHAPTER I. PAGE RACE-HORSES 825. A. Running-Horse 825 B. Steeple-Chaser 827 C. Trotters (in Harness or under the Saddle) 829 CHAPTER II. HORSES OF LUXURY 833 A. Coach-Horses (Large and Small Coach-Horses) 833 B. Saddle-Horses (Hackney, Cob, Hunter, Double Pony, Pony) 837 CHAPTER III. CAVALRY HORSES 844 A. Staff Horses 845 B. Troop Horses 846 CHAPTER IV. HORSES OF INDUSTRY AND COMMERCE 849 A Slow Heavy-Draught Horses . 851 B. Fast Heavy-Draught Horses 852 SECTION EIGHTH. VICIOUS HORSES. CHAPTER I. WHIMS AND Vicious HABITS . 858 1. Horses which loll the Tongue, double it up, or continually protrude it from the Mouth 859 2. Horses which strike the Lower Lip against the Upper 859 3. Horses which rub the Lower Extremity of the Head against the Man- ger, or the Tail against surrounding Objects 860 4. Horses which shake the Head or jerk the Reins 860 5. Horses which grasp the Branches of the Bit with the Lower Lip . . . 861 6. Horses which tear their Blankets with the Teeth 861 7. Horses which rest one Hind-Foot upon the other 861 8. Horses which lie down Cow-Fashion -. . . . 862 XX CONTENTS. PAGE 9. Horses which strip their Halters 862 10. Horses which roll as soon as they are harnessed or when they return to the Stable after working 863 1 1 . Horses which trot in the Stable : 863 12. Horses which paw in the Stable 864 13. Horses which weave in the Stable 864 14. Horses which eat Earth 864 15. Horses which have the Vice of " Wind-Sucking," or swallowing Air . 865 CHAPTER II. VICES PROPERLY SO CALLED 869 | 1. External Manifestations Proper to each Vice 869 1. Balky Horses 869 2. Horses difficult to Approach or to Groom . . 870 3. Horses difficult to Harness or to Mount 871 4. Horses difficult to Shoe 871 5. Biters , 872 6. Horses which rear and strike with the Pore-Feet 873 7. Horses which back 874 8. Kickers 874 9. Timid Horses, Shyers 876 10. Aversion to Special Objects 877 11. Runaway Horses 879 2. General Causes of Vices 882 CHAPTER III. CHOICE OF THE HORSE 886 1. The Seller 887 2. The Purchaser 892 3. Examination of the Horse 894 4. Horses mated or paired 901 5. Horses which may be mounted or driven at will 903 LIST OF ILLUSTRATIONS. FIG. PAOE 1. Situation of the Centre of Gravity in the Horse 4 2. Determination of the Centre of Gravity 5 3. Stability of the Equilibrium 10 4. 5, 6. The Lever and Muscular Mechanism 12, 13 7. Lever of the First Class It; 8,9. Lever of the Second and Third Classes 17 10. The Inclined Plane 19 11. Regions of the Horse seen in Profile 24 12. Kegions of the Horse seen in Front 25 13. Regions of the Horse seen Behind 25 14. Regions of the Horse seen Laterally and in Front 26 15. Regions of the Horse seen Laterally and Behind . . . 27 16. Superficial Structures viewed in Profile 28 17. Superficial Structures viewed in Front 30 18. Superficial Structures viewed from Behind 30 19. Regions of the Head 35 20. Vertical Section of the Eye of the Horse (semi-schematic) 49 21. Examination of the Eye 52 22. Examination of the Eye 53 23. Normal Eye 54 24. Examination of the Nostril 62 25. Interior of the Mouth (after Bruneau) 70 26. Examination of the Mouth 77 27. Bit of the Bridle 80 28. Directions of the Head and the Neck 89 29. Directions of the Head and the Neck 90 30. Directions of the Head and the Neck 92 31. Over-check Rein 92 32. Direction of the Neck 101 33. Direction of the Neck 103 34. Coxse 124 35. The Coxa as a Bent Lever 124 36. Length of the Croup , 126 37. Openness of the Ilio-ischial Angle . 126 38. Variations in the Inclination of the Ilium 132 39. Variations in the Inclination of the Ischium 133 40. Simultaneous Variations of the Ischium and the Ilium 134 41. Influence of the Misplacement of the Coxae as a whole . 135 xxi xxii LIST OF ILLUSTRATIONS. FTG. PAGE 42, 43. Convexity of a Curve . 153 44. Convexity of the Kibs 155 45. State of the Hairs of the Tail 170 46. Docked Tail, with the Hairs long 171 47. 48, 49. Docked Tail, with the Hairs shortened 171, 172 50, 61. Horse in the Act of Pulling 187, 189 52, 63. Limits of Extension and of Flexion 191, 193 54. Schemes of the Evolution of two Congeneric Members during the Phases of Contact and of Elevation 194 55. Action of the Anterior Member in the Trot 197 56. Action of the Posterior Member in the Trot 199 57. Length of the Shoulder 204 58. Length of the Shoulder in Relation with the Arm 206 59,60,61. Direction of the Shoulder 207,208 62. The Scapulo-humeral Angle 209 63. Direction of the Arm 216 64. Scheme of the Muscular Incidences of the Straight and the Oblique Arm . 217 65. Compensation of the Straight Shoulder by an Oblique Arm 218 66. . The Olecranon as a Lever-arm 220 67. Form of the Knee 229 fJ8, 69, 150, 161. Direction of the Knee in an Antero-posterior Sense . 231, 232, 450 70, 71. Direction of the Knee in Relation to the Median Line 233 72. Scheme of the Direction of the Thigh 241 73, 74. Length of the Thigh 242 75. Scheme of the Width of the Leg 249 76. Tendons and Tendinous Bursae of the Hock 254 77. Form of the Hock . . . '. 256 78. Scheme of the Rigidity of the Posterior Member 259 79. Straight Tibia 264 80. Oblique Canon 266 81. 82. Deviations of the Vertical Axis of the Hock 269 83. Capped Hock '..~ 270 84, 85. Curb and Spavin 273 86. Spavin 274 87. Jarde 275 88. Jarde upon the Dissected Hock 276 89. Jarde upon the Macerated Hock 277 90. 91. Different Views of the Dissected Hock 278 92, 93, 96, 97. Bones and Ligaments of the Canon, Fetlock, Pastern, and Coronet * 280, 291 94, 95. Width of the Canon 285 98. Mechanism of the Articulation of the Fetlock . . 292 99, 100. Scheme of the Length of the Pastern 301,302 101, 102,152,153. Direction of the Pastern 304,450 103. Disadvantages from Excess or Insufficiency of the Obliquity of the Pastern 305 104, 105. The Pastern as a Lever 306 106. Longitudinal and Median Section of the Foot 314 107. Normal Foot before and after Maceration 315 108. Foot viewed in Front 316 109. Profile of the Hoof 317 110. Wall of the Hoof . 317 LIST OF ILLUSTRATIONS. xxiii FIG. PAGE 111. Inferior Face of the Hoof 317 112, 113. Antero-posterior and Transverse Sections of the Hoof 318 114. Interior of the Hoof 319 115. Transverse Section of the Hoof (Posterior Part) 319 116. Frog and Periople . / 319 117. Hoof with Perioplic Band detached 320 118. Views of the Fore-foot 320 119. Hind-foot .~T ~321 120. Foot with High Heels 331 121. Foot with Low Heels '. 331 122. Foot, Pincard 333 123. Deformity of Hoof from Laminitis 338 124. Keraphyllocele * 339 125. The Proportions, after Bourgelat 347 126. The Proportions of Eclipse, after Saint-Bel 351 127. The Proportions of the Horse seen in Profile , 360 128. The Proportions of the Head viewed in Profile . . . 362 129. The Proportions of the Head viewed in Front 363 130. Comparative Proportions of the Man and the Horse 364 131. Articular Angles, after Morris 366 132. Anterior Member with the Oblique Segments inclined Forty-five Degrees to the Horizon 368 133. The same in the Posterior Member 368 134. The Articular Angles upon a Drawing, from a Photograph of Fitz- Glad- iator 372 135. Toise , 373 136. Measurement of the Inclination of the Segments 375 137. Use of the Arthrogoniometer 376 138 Arthrogoniometer for measuring the Articular Angles 376 139. Value of the Articular Angles in the Fore Member 381 140. Value of the Articular Angles in the Hind Member 381 141. Length of the Body 388 142. Length of the Body not dependent upon that of the Vertebral Column . 390 143. Length of the Body as modified by the Obliquity of the Shoulder and the Croup 392 144. The Hassembler ' 440 145. The Camper 440 146. The Placer 441 147. Lines of Equilibrium of the Horse viewed in Profile . 444 148. Scheme of the Lines of Equilibrium 445 149. Normal and Abnormal Axes of the Fore Member 446 154. Axes viewed in Front 451 155. Normal Axis viewed in Front 452 156. Horse too Open in Front 452 157. Bow-legged Horse 454 158. Outbow-footed Horse __ 454 159. Horse Closed in Front ' 455 160. Ox-Knee " .... 455 161. Horse Cross-footed in Front 455 162. Scheme of the Axis of the Hind Member 456 163. Normal and Abnormal Axes of the Hind Member seen in Profile .... 457 xxiv LIST OF ILLUSTRATIONS. FIG. PAGE 164. Axes viewed from Behind 460 165. Horse too Open Behind 461 166. Bow-legged Horse 462 167. Horse Closed Behind 463 168. Horse Cow-hocked 463 169. Bearing 468 170. Kicking 471 171. Scheme of the Movement of a Member during the Phases of Contact and Elevation 475 172 Exchange of Contact upon the Posterior Bipeds in the Walk 476 173. Instrument for Analyzing the Gaits (Marey) 480 174. Cylinder of Registration 480 175. Chaussure Exploratrice (Marey) 481 176. Bracelet Explorateur (Marey) 481 177. Registering Apparatus of Marey applied to the Horse 482 178. Chaussure Exploratrice for registering the Gaits by Electricity 484 179. Longitudinal Section of the same 484 180. Instantaneous Photographs of the Fast Gallop, after Muybridge 487 181. Chrono-photograph of the Walk of a Man 489 182. Chrono-photograph of the Leap of a Man 489 183. Movement of the Anterior Member of the Horse 490 184. Lecoq's Method of Notation of the Gaits 491 185. Hodochronometric Scale of Vincent and Goiffon 492 186. Notation of the Running of a Man (Marey) 493 187. Notation of the Walk of Two Pedestrians 494 188. Notation of M. Lenoble du Teil 495 189 Table for Artificial Notation of the Gaits 498 190. Model for Notation of the Gaits (Marey) 5dO 191. Model for Notation of the Gaits 501 192. Synopsis of the Notations of the Gaits of the Horse 502 193. The Amble 505 194. Notation of Two Men Walking 506 195. Notation of the Marched Amble 507 196. Trail of the Amble, after Lenoble du Teil 507 197. 198. Displacements of the Centre of Gravity 508 '199. Trail of the Broken Amble 509 200. Notation of the Broken Amble 510 201, 202,203. Trails of the Trot (Lenoble du Teil) 511 204, 205, 206. The Leaped Trot 512 207. Kinematic Analysis of the Play of the Anterior Member in the Ordinary Trot 513 208. Kinematic Analysis of the Play of the Posterior Member in the Ordinary Trot 514 209. Tracing, Notation, and Reactions of the Trot 515 210. Notation of the Ordinary Trot in which the Phase of Suspension is not Perceptible 516 211. Notation of the Marched Trot 517 212. 213. Displacements of the Centre of Gravity 517,518 214, 215, 216. The Flying Trot of the Horse Abe Edington 524 217. Trail of the Flying Trot of the Horse Abe Edington 524 218. Notation of the same 525 LIST OF ILLUSTRATIONS. xxv FIG. PAGE 219. Notation of the Canter in Front 528 220. Running Walk : Notation and Bases 529 221. Trail of the Running Walk ,530 222. Kinematic Analysis of the Play of the Anterior Member in the Walk . . 531 223. Kinematic Analysis of the Play of the Posterior Member in the Walk . . 531 224. Tracing and Notation of the Walk, with Equality of the Lateral and Diag- onal Contacts , ^ .__. 533 225. 226, 227, 228 Succession of the Contacts of the Walk 534,~535 Notation of the Ordinary Walk 535 Walk, with Predominance of the Lateral Contacts 536 231, 232, 233. Diverse Trails of the Walk 538 234. Backing ..." 543 235. Backing, in the Horse attached to a Load 544 236. Diagonal or United Gallop . . 546 237. Lateral or Disunited Gallop 546 238. Kinematic Analysis of the Play of the Anterior Member in the Gallop . . 548 239. Kinematic Analysis of the Play of the Posterior Member in the Gallop . . 548 240. Tracings, Notation, and Reactions of the Gallop of the Trained Horse . , 549 241. Notation of the Gallop in Three Times 550 242. Notation of the Full Gallop 551 243. 244, 245, 246, 247, 248, 249, 250. The Full Gallop, its Beats, Bases, and Projection 554, 555 251. Passage from Station into the Gallop 555 252. Principal Trails of the Gallop ( Barrier and Lenoble du Teil) 558 253. Displacements of the Centre of Gravity 560 254. Instantaneous Photographs of the Running Gallop of the American Horse Sallie Gardner (Muybridge) 564 255. Notation of the Running Gallop, from Instantaneous Photographs .... 565 256. Trail of the Gallop, furnished by Sallie Gardner 565 257. Transition from the Walk to the Trot 568 258. Transition from the Trot to the Walk 568 259. Transition from the Trot to the Gallop 569 260. Transition from the Gallop to the Trot 569 261. Scheme of the Three Principal Varieties of Leaps 570 262. 263, 264, 265, 266. Different Phases in the Execution of the Leap .... 571 267. Trail of the Leap over a Hedge 572 268. Notation of the Leap over a Hedge 573 269. Instantaneous Photograph of Draught-Horses moving a Heavy Load . . 577 270. Dentition of the Horse, as a whole 595 271. Deciduous Incisors viewed on their Anterior Face 598 272. Deciduous Incisors (Profile and Dental Tables) 599 273. Deciduous Pincer 600 274. Magnified Longitudinal Section of a Superior Virgin Pincer of the First Dentition, seen in its Alveolus 600 275. Longitudinal Section of the Jaws, showing the Relative Situation of the Milk and Permanent Incisors 601 276. Unworn Inferior Pincer of the Second Dentition 602 277. Superior Virgin Incisor of the Second Dentition (Pincer) 603 278. Longitudinal Section of a Permanent Incisor that has been used ... 604 279. Eccentric and Longitudinal Section of a Superior and Inferior Permanent Intermediate . . 604 xxvi LIST OF ILLUSTRATIONS. FIG. PAGE 280. Longitudinal and Median Sections of the Pincer, Intermediate, and Corner in each of the Jaws 605 281. Series of Longitudinal Sections of the Right Inferior Incisors of a Five- year-old Horse 607 282. Schematic Section of the Dental Follicle of an Inferior Incisor of a Horse 608 283. Longitudinal and Median Sections of a Permanent Inferior Pincer (en- larged) 609 284. Radical Cementation of the Incisors of a Horse 610 285. Longitudinal Antero-posterior Section of an Inferior Pincer, etc. .... 611 286. Median and Longitudinal Sections of Incisors, showing, 1st, the Growth of the Teeth at their Roots ; 2d, the Progressive Wear of their Tables ; 3d, their Length and Obliquity according to the Age ; 4th, Obliteration of their Pulp Cavities ; 5th, finally, their Radical Cementation 613 287. Transverse Section of Inferior Right Pincer, showing the Different Layers constituting the Tooth, with their Relative Thickness (Magnified Five Diameters) 614 288. Incisive Arcades exposed to show the Progressive Inclination of the Teeth in Relation to the Plane of Meeting of the Jaws 617 289. Incisors exposed by their Anterior Face to show their Relative Inclination towards the Median Line 618 290. Double Inferior Right Canine Tooth in the Ass 620 291. Superior Right Canine Tooth 621 292. Longitudinal and Median Sections of the Canines 621 293. The Three Superior Deciduous Molars (Right Side) 623 294. The Three Inferior Deciduous Molars (Right Side) 624 295. Transverse Section of the Inferior Jaw, showing the Relation in the Al- veolus of the Permanent and Deciduous Molars at the Moment of Eruption 625 29"6. Transverse Section of the Superior Jaw, showing the Relation in the Alve- olus of the Permanent and Deciduous Molars at the Moment of Eruption 626 297. Superior Permanent Molar (Right Side, Virgin Tooth) 627 298. Superior Molar Arcade of the Right Side of a Horse Six Years Old Past . 628 299. Inferior Molar of the Second Dentition (Left Side, Virgin Tooth) .... 630 300. Inferior Molar Arcade of the Left Side of a Horse Six Years Old Past . . 631 301. Superior Right Molar removed from its Dental Follicle 632 302. Inferior Left Molar removed from its Dental Follicle 633 303. Table of Superior and Inferior Molars 634 304. Inferior Left Molar Arcade of a Very Old Horse, showing the Radical Cementation 634 305. Transverse Section of a Superior Left Molar (enlarged) 635 306. Superior Left Molar Arcade of the Hipparion 636 307. Transverse Section of an Inferior Right Molar (enlarged) 636 308. 309, 310, 311. Supernumerary Incisor Teeth 722, 723 312. Double Right Inferior Canine in the Ass 724 313. Absence of the Inferior Corners 725 314. Union of Two Superior Incisors . 726 315. Fissure of the Infundibulum of the Incisors 727 316. Double Infundibulum of the Incisors 728 317. 318. Superior and Inferior Brachygnathism 737 319. Parrot Mouth 740 320. Reversed Parrot Mouth ..... .742 LIST OF ILLUSTRATIONS. xxvii FIG. PAGE 321. Incisors of the Inferior Jaw too Short 744 322. Inferior Molar Arcade of a Very Old Horse, showing the Radical Cementa- tion, as well as the Insufficient Length of the Middle Teeth 745 323. Eight Molar Arcades of a Very Old Horse 746 324. Bevelled Molars from Irregular Wear 748 325. Hypertrophy of the Fourth Right Superior Molar 750 326. Abnormal Wear produced by Cribbing . 755 327. Abnormal Wear produced by Cribbing 750 328. Abnormal Wear produced by Cribbing 757 329. Abnormal Wear produced by Cribbing 759 330. Hippometer with Pedestal 808 331. Hippometer without Pedestal 809 332. Hippometric Cane 810 333. Running-Horse, Vermout, Winner of the Great Prize of Paris in 1864 . . 826 334. Steeple-chase Horse, Bois-Roussel, Winner of the French Derby in 1864 . 828 335. Trotter in Harness, Fazan, Russian Stallion of the Orloff Variety .... 831 336. Trotter under the Saddle, Bayadere, Anglo-Norman Mare 832 337. Large Coach-Horse, Lahore, Half-thoroughbred Anglo-Norman 835 338. Small Coach-Horse, Shang-Hai, Half-thoroughbred Anglo-Norman . . . 837 339. Hackney 838 340. Cob 840 341. Hunter 841 342. Double Pony 842 343. Pony 843 344. Slow Heavy-draught Horse 851 345. Fast Heavy-draught Horse 853 346. Velocite, Percheron Mare of the Compagnie Generals des Omnibus . . . 854 PLATES. PLA.TE PJLOE I. Birth 603 II. About One Week 664 III. One Month 665 IV. Three Months 666 V. Four Months 6C7 VI. Five Months 669 VII. Ten Months 671 VIII. One Year 673 IX. Sixteen Months 675 X. Twenty Months 677 XI. Two Years 679 XII. Kising Three Years 681 XIII. Three Years Past 683 XIV. Eising Four Years 685 XV. Four Years 687 XVI. Four Years Past 689 XVII. Rising Five Years . . 691 XVIII. Five Years 693 XIX. Six Years 695 XX. Seven Years * 697 XXI. Eight Years 699 XXII. Nine Years 701 XXIII. Ten Years 703 XXIV. Eleven Years 705 XXV. Twelve Years 707 XXVI. Thirteen Years 709 XXVII. Fifteen Years 711 XX VI 11. Seventeen Years 713 XXIX. Nineteen Years 715 XXX. Twenty-one Years 717 XXXI. Thirty Years 719 XXXII. Begu. Nine Years 731 XXXIII. False Begu. Fourteen Years 735 XXXIV. Bishoping 769 XXVlll THE EXTERIOR OF THE HORSE. SECTION FIRST. PRELIMINARY IDEAS OF ANIMAL MECHANICS. CHAPTER I. OBJECT, END, AND UTILITY OF THE EXTERIOR. THE term exterior of the horse seems to have been employed by veterinarians only since the close of the last century, dating from the period when Bourgelat published his book upon the external form of the horse in 1768, six years after the foundation of veterinary schools. Before his time veterinarians and horsemen had entered but super- ficially upon the study of the forms of the horse. They had limited themselves in their works to determining, sometimes by figures, the principles relating to the proportions. These efforts, however, had passed, so to speak, unperceived, were lost among the publications of the times and drowned in the midst of the different writings of which the numerous veterinary treatises were composed. Here, as in the other branches of veterinary science, Bourgelat was endeavoring to establish principles to guide the pupils who flocked into his schools. If it be remembered that this innovator was an eminent master as well as a skilful horseman, we will not be astonished to see that he has reached with the greatest ease, in his treatise on the exterior, if not absolute perfection, at least that degree of exactness which it was just to demand at that epoch from a man who turned everything into in- struction. Bourgelat more than all others was conscious of the great utility of the horse, and the necessity of preparing in a special manner 1 2 THE EXTERIOR OF THE HORSE. the professional men whom he gave to the agricultural world. He desired that they should be well acquainted with and appreciate the qualities and the defects of this merchandise, which every day gained more importance and acquired a greater value. The inauguration of instruction upon the exterior dates from this period. Its object is to enable the scholar to determine by a rapid examina- tion of the form of a horse his relative commercial value in the service in which he is to be employed. In 1837, 1 H. Bouley had already stated its object as follows : " Given the external conformation of an animal, we determine the service in which he may be employed and estimate the amount and duration of the effects which his machinery is capable of producing." This study, we see, is only a branch of zootechnics, but differs from the latter in that it does not seek the conditions for the amelioration of the equine races. It is intended, rather, to be a guide in the choice of an animal at the sale. Its importance to the horseman is such that the necessity of forming a distinct course for its study and devoting to it extended investigations is understood. This study is, then, es- pecially an applied science, and it is therefore indispensable before entering upon it to have a certain knowledge of anatomy, physiology, mechanics, physics, hygiene, zootechnics, and pathology. In order to be able to understand it well, its theory should first be learned. A knowledge of the horse is a problem full of difficulties when its application is to be made to any given animal. It is only through constant habit that we can succeed in forming by a rapid examination a good judgment of his value as a beast of service. No doubt this result may be obtained without having undertaken ana- tomical and physiological studies. It is sufficient to possess what tradesmen call judgment, a glance of the eye ; but this is only acquired by long practice. We all know what perfection in this respect is acquired by certain persons quite ignorant of the sciences which are applied to the exterior. The officers of our remounts, of our studs, even simple horse-dealers, astonish us sometimes by the rapidity with which they see in a horse the weak point, the defect, and the blemish ; they have, moreover, that veritable tact of knowing how to adapt them- selves, in their purchases, to the exigencies, modes, and fancies of the times. However, the time which it has taken them to obtain this result must be considered. Theoretical ideas have precisely the effect of shortening this time ; they are, for beginners, aids which experience 1 Maison rustique du XIX sidcle, t. ii. CENTRE OF GRAVITY. 3 will allow them to dispense with, but without which they could not rise above this empirical knowledge, appanage of the ignorant or of the coxcomb, who accepts under the same title the true and the false, and who is incapable of distinguishing otherwise than by the routine with which he proceeds. If the knowledge of the horse is an art, it is especially one which consists in observing, comparing, and judging according to positive information. Besides, it is necessary, in order to reach perfection, to have observed much, to have put into practice that faculty which makes the clinician, the connoisseur, and the artist. It is when such an edu- cation is carried to a considerable extent that we succeed in seizing at once what good or defective qualifications the horse possesses, and that it is possible to form a just conclusion by appreciating to what degree the good qualities exceed the bad. CHAPTER II. CENTRE OF GRAVITY. THE simultaneous actions of the force of gravity upon all the molecules of a body may be considered as so many small parallel forces having the same purpose and the same direction, whose total sum is the weight of the body, and whose result is applied to one point which is the centre of gravity. The vertical pressure of the centre of gravity to the ground is called the line of gravitation (line of gravity, Raabe & Bonnal). We have just seen that the result of these forces is equal to their sum, and that the position of its point of application depends upon the intensity of its components. All the actions of the force of gravity being equal for each molecule of the same kind, if these molecules of a body are uniformly distributed, in a word, if the latter be homogeneous, it will in all its parts be equally attracted by this force. Therefore, nothing will be easier than to determine the centre of gravity, especially if the body has a geometrical form. Special procedures are employed to determine the location of this centre in a body, whatever may be its form. We will not speak of this at present. Seldom, however, are bodies found in conditions sufficiently homogeneous for its determination to be simple. Certain parts are much more dense than others, and therefore the force of gravity attracts them more. The result of this is that the centre of gravity, instead of being situated in the middle of the body, is drawn nearer, as has been seen, to the parts which weigh the most. This is observed in organized bodies. Its Determination in Animals. In animals new difficulties arise. The vital phenomena being only the phenomena of movement, the material particles 4 THE EXTERIOR OF THE HORSE. at each instant are displaced in different directions, and thus are modified the weight and volume of the organs in which the molecular changes take place. Other displacements, much more considerable, indeed even more important from the point of view which concerns us, are due to the actions of the organs, the different attitudes of the body, or the movements which are caused by locomo- tion. We understand, then, how. difficult becomes the exact determination of the centre of gravity, and the great importance of sufficiently appreciating its FIG. 1. Situation of the centre of gravity in the horse. displacements when it is a question of obtaining from it the conditions of equi- librium. According to Borelli, 1 the centre of gravity in the horse is situated in the middle of the height of the trunk, and the line of gravitation falls through the centre of the quadrilateral formed by the four members. According to Professor Colin, 2 it almost corresponds to the intersection of two lines, one of them (vertical) passing back of the xiphoid appendix of the sternum, the other (horizontal) separating the middle from the inferior third of 1 Borelli, De motu animalium, Naples, 1734. p. 126. 8 G. Colin, Trait6 de physiologic comparee des animaux, 3e edition, Paris, 1886, t. i. p. 460. CENTRE OF GRAVITY. 5 the body (Fig. 1). Further on, the same author adds : " It is clear that the posi- tion of the centre of gravity and the distribution of the weight of the body upon the members must vary very much according to the conformation of animals whose head, neck, abdomen, and croup present such diverse proportions." The position of the centre of gravity of the horse, as indicated by M. Colin, seems to us very nearly correct, at least judging from the experiments which we have conducted. At first, it seems extremely probable that this point is situated in the median plane of the body. In effecting a series of weighings bearing alternately upon both of the lateral bipeds of the same subject maintained as much as possible in an invariable attitude, we succeed in determining that the left lateral biped, for example, supports a weight very nearly equal to that of the right lateral biped. On the other hand, if, from the example of MM. Eaabe and Bonnal, 1 we consider that the dorso-lumbar column A, Fig 2, measuring the interval comprised be- FIG. 2. tween the centre of the movement of the shoulder and that of the haunch, that is to say, the length of the base of support of a well-formed horse, is attracted by two parallel forces F and F', distributing the weight of the body upon the posterior and anterior bipeds, it will be easy to determine with considerable approximation the position of the point P, through which passes the line of gravitation, that is to say, the resultant of these two forces. It is known that this point divides the line AB into two parts inversely proportional to the forces F and F', in such a way that we have ~F 7 = PA _% 1 Raabe et Bonnal, Determination des lignes de gravite du cheval, etc. In Archives v6tri- naires, 1883, p. 538. 6 THE EXTERIOR OF THE HORSE. Here are, in fact, the results which we have obtained by the aid of this procedure upon a saddle-horse of a fine form provided with good equilibrium, that measured 1.55 m. at the withers and at the croup, and 1.53 m. from the point of the shoulder to the point of the buttock. The subject, saddled and bridled, was weighed, the neck at 45 degrees and the head elevated. Its base of support, AB, was equal to 1.20 m. As to the total weight, which was 445 kilogrammes, it was distributed thus : Upon the anterior biped 257 kil. (F'). Upon the posterior biped 188 kil. (J^). In the particular case of which we are speaking, the point P divides the line AB, which unites the two forces, into two parts inversely proportional to their intensity. We have then JL = IM or = AB PA F' PA PA By the addition of the denominators to each of the two terms of this equation we obtain F+ F' = AB PA + PA = AB . F' PA PA' whence PA = F ' F *A* = 257X 4 4 5 2 m ' = ' 69 m - and PB = 120 m. 0.69 m. = 0.51 m. The line of gravitation then falls upon the horse submitted to the experi- ment at 0.51 m. posterior to the anterior biped. This is about the position which MM. Raabe and Bonnal have assigned to it. The line of gravitation of the Arab mare upon which these horsemen experimented was situated 0.69 m. in front of the coxo-femoral centre and 0.47 m. from the centre of movement of the shoulder. The distance of its two centres of movement was 1.17 m. instead of 1.20 m. As to its bipeds, they weighed : the anterior, 270 kilogrammes the posterior, 184. In this case, the distribution of the weight, although analogous to that of our horse, differs from it, since in the latter the surplus weight of the anterior bipeds is only 69 kilogrammes, whilst in the mare it reached 86 kilogrammes. The more anterior position of the line of gravity in the latter is thus explained. MM. Kaabe and Bonnal have deduced with reason the practical importance of obtaining as precise a determination as possible of the centre of gravity. The ideal to be realized, when we think of placing a dorsal burden upon a horse, should, in fact, consist in distributing this burden upon each biped proportionally to the weight which it bears in the natural state. In these conditions the centre of gravity preserves its normal position and one of the bipeds is never relieved at the expense of the other. In 1835, Morris and Baucher 1 had already experimentally determined in the horse the displacements of the centre of gravity, by changing the position of the head and neck, as well as that of the rider. "With this purpose," says Morris, " M. Baucher, a horseman, and myself were going to the general mart of the Custom-House at Gros-Caillou to weigh horses upon scales of proportion with movable planks invented a few years ago. . . . " The two weighing-machines were placed in such a manner that the anterior extremities rested upon the middle of the first and the posterior extremities upon the middle of the second. 1 Morris, Essai sur I'ext6rieur du cheval, Paris, 1857, p. 41. CENTRE OF GRAVITY. 7 The two planks being exactly upon the same level, and belonging to weighing-machines of the same proportion, could therefore be taken for two ^cales of an ordinary balance. We equipped a saddle-mare regularly formed, although the head and neck were stronger than the remainder of the body. She was bridled and saddled. " The scales being abandoned to the weight of the mare held in a complete state of immo- bility, the head being in its ordinary position, rather low than high, gave us the following results : Fore Extremity. Hind Extremity. Total Weight. Difference. 210k. 174k. 384k. 36k. " A fluctuation of from 3 to 5 kilogrammes was established, which settled alternately upon the fore and hind extremities, on account of the movements produced by the organs of respiration. " We lowered the head so that the end of the nose reached the level of the chest. This movement effected and the immobility obtained in this position, the fore extremity increased 8 kilogrammes, of which the hind was relieved. Fore Extremity. Hind Extremity. Total Weight. Difference. 218k. 166k. 384k. 52k. " The head being raised until the end of the nose was on a level with the height of the withers, the same precautions for immobility being observed, the fore extremity displaced 10 kilogrammes of its weight upon the hind and then balanced itself, with the following results : Fore Extremity. Hind Extremity. Total Weight. Difference. 200k. 184k. 384k. 16k. " The head, being returned to its former position, was drawn back upon the neck and ele- vated somewhat by the action of the bridle. Ten kilogrammes were then displaced backward as follows : Fore Extremity. Hind Extremity. Total Weight. Difference. 202k. 182k. 384k. 29k. These results evidently prove that the more the head is raised, if not natu- rally, at least by the action of the hand, the more its weight and that of the neck are equally distributed upon the extremities, if the position be not forced. " After these experiments M. Baucher mounted the mare, and the two scales poised with the following weights : Fore Extremity. Hind Extremity. Total Weight. Difference. 251k. 197k. 448k. 54k. " The rider placed in an academic position, his weight of 64 kilogrammes was distributed as follows : 41 kilogrammes upon the anterior members and 23 upon the posterior. " Being seated in such a manner that the upper part of the body leaned backward, M. Baucher displaced 10 kilogrammes upon the hind extremity. Then drawing the horse's head backward according to his method, he again charged the same with a weight of 8 kilogrammes : total, 18 kilogrammes. In this position we obtain : Fore Extremity. Hind Extremity. Total Weight. Difference. 233k. 215k. 448k. 18k. " By bearing entirely upon the stirrups, the weight on the anterior members increased 12 kilogrammes. " Afterwards we placed a gray horse of a vicious disposition upon the scales, which, with differences already well indicated in construction, furnished us with analogous results." 8 THE EXTERIOR OF THE HORSE. In union with Bellanger, first veterinary flugelman, 1 Morris instituted a second series in 1857. The following* are the results : OBSERVATIONS UPON HORSES. WEIGHT : HEAD AT FORTY- FIVE DEGREES. WEIGHT : HEAD RAISED AND DRAWN BACK- WARD. WEIGHT : HEAD LOWERED AND DRAWN TO- WARDS THE CHEST. Fore Extremity. Hind Extremity. 1 Fore Extremity. Hind Extremity. 1 Fore Extremity. Hind Extremity. 1 Average of eleven horses. Good conformation, head and neck light Kil. 260 246 240 245 250 240 260 270 235 Kil. 195 200 195 200 195 210 200 200 215 Kil. 455 446 435 445 445 450 460 470 450 Kil. 250 240 235 235 240 236 250 265 230 Kil. 205 206 200 210 205 214 210 205 220 Kil. 455 446 435 445 445 450 460 470 450 Kil. 267 250 245 255 260 244 270 265 240 Kil. 188 195 190 190 185 206 190 205 210 Kil. 455 446 435 445 445 450 460 470 450 J Average of eleven horses. Body well proportioned, neck short, head strong Average of two horses. Body well formed, neck short, head ordinary Average of two horses. Neck strong, head light Average of two horses. Neck long, head ordinary . . One horse. Neck strong, head strong, croup short and oblique , . . . One horse. Neck and body well formed, head strong One horse. Neck strong, head strong .... One horse. Neck strong head strong " It may be remarked, in considering these different weights," General Morris adds, " that the weight of the fore extremity is about one-ninth greater than that of the hind ; that the change of the position of the head causes the weight of the fore extremity to differ from that of the hind by 10 kilogrammes ; that long necks give more weight to the fore extremity than short and strong ones ; that the fore extremity is heavier than the hind." M. Colin has repeated the first of these experiments upon two horses, and arrived at results entirely concordant. Our Experiments. We will say that most of these have been made upon fifty horses of different sizes and races, chosen from the hospital of the school at Alfort. 1 Morris, loc. cit., p. 44. CENTRE OF GRAVITY. 9 We have also sought to appreciate the extent of the posterior and anterior dis- placements of the line of gravitation in other different conditions, for example, with the mounted horse, according as the rider sits erect, leans forward or backward, or as he carries his head high or low. The displacements of this line are then determined, whether in front of or behind its average position, which oscillate be- tween two and six centimetres, sometimes more, according to the case. Differ- ences of weight, quite considerable, are equally produced in weighing both of the lateral bipeds when the head, the neck, the trunk, or the rider is inclined ~to one side, facts which show the importance of the lateral displacements of the centre of gravity during locomotion, especially the work of dressing. But it is in horses high or low in front that the variations of the weight of the fore or hind extremity assume importance. These have no longer the momentary or accidental character of the preceding, and from this fact always involve, accord- ing to the case, a permanent surcharge of one of the two bipeds, anterior or posterior, and consequently their premature ruin. Their gravity augments in horses low over the withers when from the nature of their employment they are obliged to carry burdens, as in the service of the saddle, the shafts, or the pack-saddle. In order to prove this, we weighed successively several subjects, by placing them first upon the plank of a weighing-machine perfectly horizontal ; then we raised gradually sometimes the anterior quarters, sometimes the posterior, so as to obtain, at will, horses having the fore or hind quarters low. The height was carefully noticed at the beginning of each trial, and then it was known exactly how much the croup or the withers were raised or lowered. The results were then in all points comparable, since in all cases the observations were made upon the same subject. They were found to be in conformity with the theory, and may be considered as a corroboration of the preceding experiments. We have chronicled them in the following tables : l.-ELEVATION OF THE HEIGHT AT THE WITHERS. S DISTRIBUTION _o 2 DISTRIBUTION .2 OF S bO - OF a 1 A ^j WEIGHT. IE JS| WEIGHT. I s3 5 ad 2 * '3 . ha "si S og . M .. . ?! Observations. .2 w s| $< * 1 S 11 If |l o> 5P .? 3 1 2 rf S ^1^ -2 oi S b ill "S '3 o CJ S O 5 x ^ S o3 c s M w W H <& OnC? w P m M.C. M.C. Kil. Kil. Kil. Kil. M.C. Kil. Kil. Kil. 1 1.47 1.52 465 250 215 35 0.10 245 220 25 Common mare. 2 1.68 1.69 688 374 314 60 010 368 320 48 Percheron gelding. 3 1.46 1.48 428 245 183 62 0.11 238 190 48 Common mare. 4 1.44 1.45 314 184 130 54 0.11 175 139 36 Barb. mare. 5 1.58 1.63 488 272 216 56 0.04 268 220 48 Thorough, horse. 6 1.62 1.61 526 308 218 90 0.06 306 220 86 Norman gelding. 7 1.65 1.66 570 310 260 50 0.06 308 262 46 Percheron gelding. 8 1.65 1.62 550 310 240 70 0.06 307 243 64 Norman mare. 9 10 1.39 1.47 1.39 1.50 330 445 200 260 130 185 70 75 0.06 0.06 195 255 135 190 60 65 Corsican gelding. Irish cob. 11 1.65 1.61 630 370 260 110 006 365 265 100 Boulon. gelding. 12 1.54 1.53 455 288 167 121 0.06 284 171 113 Percheron gelding. 13 1.51 1.52 410 245 165 80 0.06 230 180 50 Corsican gelding. 14 1.59 1.60 465 260 205 55 0.06 250 215 35 German gelding. 15 1.15 1.20 235 137 98 39 0.06 125 110 15 Female ass. 10 THE EXTERIOR OF THE HORSE. 2.-ELEVATION OF THE HEIGHT AT THE CROUP. e 2" DISTRIBUTION 8 33 J3 DISTRIBUTION g c? OF "c bo OF "C g ja p WEIGHT. $ . O ** d, WEIGHT. -S 3 " g * C gj W <-! c 2 V, J 9 tt-i "S o o| gS Observations. O 83 oj j^ c * O tn ^ S OJ f-t CC oE 5 S h I I g || 11 I* o gfs II 'S 5 ^ S o3 K K W E- % ^ W 5 < $ M.C. M.C. Kil. Kil. Kil. Kil. M.C. Kil. Kil. Kil. ! 1.47 1.52 465 250 215 35 0.10 258 207 51 Common mare. 3 1.68 1.46 1.69 1.48 688 428 374 245 314 183 60 62 0.10 0.11 380 252 308 176 72 76 Pereheron gelding. Common mare. 4 1.44 1.45 314 184 130 54 0.11 186 128 58 Barb. mare. 5 6 1.58 1.62 1.63 1.61 488 526 272 308 216 218 56 90 0.04 0.06 279 323 209 203 70 120 Thorough, horse. Norman gelding. 7 8 1.65 1.65 1.66 1.62 570 550 310 310 260 240 50 70 0.06 0.06 312 315 258 235 54 80 Pereheron gelding. Norman mare. 9 1.39 1.39 330 200 130 70 0.06 203 127 76 Corsican gelding. 10 1.47 1.50 445 260 185 75 0.06 230 215 15 Irish cob. 11 1.65 161 630 370 260 110 0.06 372 258 114 Boulon. gelding. 12 13 14 1.54 1.51 1.59 1.53 1.52 1.60 455 410 465 288 245 260 167 165 205 121 80 55 0.06 0.06 0.06 293 260 265 170 150 200 123 110 65 Pereheron gelding. Corsican gelding. German gelding. 15 us 1.20 235 13, 98 39 0.06 142 93 49 Female ass. Let us see now what is understood by the terms equilibrium and base of support. Equilibrium in mechanics is the state of a body induced by the forces which destroy one another or which are annulled by a resistance (Littre). In animals the body seldom rests upon the ground by a continued surface (decubitus). It is supported by four broken columns ar- ticulated from distance to distance and desig- nated by the name of members. The polygon formed by the lines joining the four points which touch the ground at rest represents what is called the base of support. This polygon is sometimes a triangle; at other times the base of support is reduced to a line ; finally it may -be only a point. What- ever may be the form and extent of the base of support, it is necessary, in order to obtain equilibrium, that the line of gravitation does not meet the ground outside of this base. The equilibrium will be so much more stable as the base of support becomes larger, the centre of gravity placed lower, and the line of gravitation nearer the centre of the base. It will be unstable in the contrary con- ditions. In fact, in the solid here represented (Fig. 3) it will be seen that if the centre of gravity is displaced from A to (7, having reached to the point (7, the slightest oscillation of one side or the other, (7(7 for example, will cause the line of THE LEVER AND MUSCULAR MECHANISM. 11 gravitation to come outside of the base and provoke a fall. Therefore, a horse having a heavy body mounted upon long, slender members drawn close to the median plane will be endowed with an equilibrium relatively unstable. As the base of support has the form of an elongated rectangle, with the horse at rest, the displacement of the centre of gravity from in front backward will be much less dangerous for the integrity of its equilibrium than those which take place from side to side, because the line of gravitation will be moved much easier from the base of support in the latter case than in the former. This explains-4o us why falls during rapid paces scarcely ever take place upon a straight line, but are produced, on the contrary, in turning ; why the ambling horse, which moves his members by lateral bipeds, goes faster and falls more frequently than the trotting horse, which moves his members by diagonal bipeds ; why the leaping horse, which displaces the centre of gravity greatly, falls down so often ; why sliding sideways is more dangerous than moving forward or backward, etc. That instability of equilibrium gives the measure of speed has been justly said. It is easy to account for this. If, from the fact of its displacements, or from its situation being more or less raised, it is carried outside of the base of support, it will cause the members to be displaced with a greater rapidity to sup- port the body, as the fall is more imminent. The race-horse lengthens his body, extends his head and neck, and seems almost to lie down upon the ground in such a manner as to bring, as much as possible, the centre of gravity in advance of the movement. The dressed horse raises himself in a strong proportion in order to execute more easily the varied movements which at every instant his rider exacts from him. His paces are shortened, raised; his equilibrium is more stable, the displacements of his centre of gravity less extended but more numerous. On account of his acquired speed, and especially because of the instability of his equilibrium, the hippo- drome-horse can scarcely make progress upon a straight line ; the slightest lateral displacement of the centre of gravity, a little sudden, causes him to fall. CHAPTER III. THE LEVER AND MUSCULAR MECHANISM. THE lever is denned as a "rigid and inextensible rod supported upon a fixed point." The form and nature of the substance of which this stalk is com- posed have no importance from the point of view which concerns us. It is seen, then, that the bones of the skeleton are properly considered as levers, since they enter into the definition which we have just given. Every lever may be submitted to the action of several forces, but, whatever may be their number, we know that it is always easy to reduce them to two. When it is a question of ascertaining the conditions of the equilibrium of this machine, only two forces are usually recognized. The former will be in equi- librium when the resultant of the forces which move it is annulled by the reac- tion of the point of support. If equilibrium does not result, the effect of the forces is to determine a rotation of the stalk around the fixed point. 12 THE EXTERIOR OF THE HORSE. Of the two forces which act upon the lever, one, which is called the power, is destined to equalize the other, which is called the resistance, or to overcome its action. The object of the lever is to favor one of these forces at the expense of the other. We will see later on what its consequences are. In the animal economy, these forces are represented by the muscles, and the levers by the bones. For convenience of demonstration, we will suppose that the two forces which incite the lever are situated in the plane of the latter. In most instances it is not thus : the forces and the lever are placed in different planes. An example will explain this better. Suppose it to be a question of the adductor muscle of the arm. The lever upon which it is inserted is the humerus, the resistance which it must overcome is the weight of the member applied to the articulation of the elbow. It is then easy to determine that the humeral and vertical axis passing through the centre of this articulation, forms a plane in which the adductor muscle of the arm is not situated. If it were located there, it would determine flexion alone of that bone, which is not the case, since it promotes adduction. Among the muscles of the members, it is only the direct extensors and fiexors that are situated in the plane of their respective levers. It is the same for the muscles of the spinal column. All the others act in different planes. This does not mean that the conditions of the equilibrium of the lever are not applicable to the former, but the developments into which we must enter in order to resolve particular cases would lead us too far away. In mechanics, the moment of a force in relation to an axis is the product of the projection of this force upon a plane perpendicular to the axis, through the distance of this force to the axis. When the idea of moment is applied to the study of the lever, it may be denned thus : The product of the force by the arm of the lever, because the forces, being situated in the same plane, are themselves their projection ; as to the axis, it is supposed to pass through the point of support. Suppose the two forces F and F' inciting the lever AB (Fig. 4). The whole system is situated in the plane of the ac- tion. The forces then project FIG. 4. themselves following FA and F'B. Let us suppose now an axis perpendicular to this plane and piercing it at the point 0. It is evident that the distances of these two forces to this axis are measured by the perpendiculars OC and OD. The moment of force /'will be FX OC; that of the force F . F' x OD. The perpendiculars OC and OD are called lever-arms extending from the point of support in the direction of the forces .Fand F'. Whence it results that in the lever the moment of a force is the product of that force by its lever-arm. It is demonstrated in the same manner that the lever is in equilibrium when the moments of the two forces are equal. We will therefore obtain ; FXOC=F'XOD. THE LEVER AND MUSCULAR MECHANISM. Whence is produced : OD C FIG. 5. That is to say, that the forces are to each other inversely as the arms of their lever great force, small lever-arm, and, reciprocally, large lever-arm, small force. Again, the intensity of the forces varies according to their degree of inclina- tion. The three following cases may present themselves : 1st. The force makes a right angle with the lever-arm. It acts then with its maximum of intensity. This is, in fact, the case where the lever-arm is the most considerable; it is measured by the distance of the point of application of the force to the point of relation. 2d. The force makes an acute angle (Fig. 5). Let the force F act upon the lever AOB. If it acted perpendic- ularly, its lever-arm would be AO. Now, OA is > than OC, as oblique upon AFvtith reference to the per- pendicular OC, arm of the lever of F. Thus a certain part of the force employed in repelling the fixed point is lost for the movement of the point A. This is seen by de- composing F into two forces, AE and AD, acting upon the point A, following the directions indi- cated. AD is the quantity em- ployed to repel the fixed point. It may be conceived that the more the angle formed by the force with its lever-arm is acute, the greater will be the increase of AD at the expense of AE, and the force utilized for the movement will thus be less. The disposable force will be null if F becomes parallel to the arm of its lever. 3d. The force makes an obtuse angle (Fig. 6). In this case the arm of the lever OC is smaller than if F were perpendicular to OA, since it would be OA itself. Thus a certain part of F is lost in drawing A tow- ards AD at the expense of the movement. The more the inclina- tion of F is obtuse, the more the component AD will increase rela- tively to the component AE, alone useful for the movement. The parallelism of F with its arm would cause, as in the preceding case, total annulment of AE, without there being any possible movement. Thus it results from the preceding remarks that every time a force is not perpen- dicular to its lever-arm, a i? IG O. part of its intensity will be attracting or repelling the point of support according to the nature of the angle formed. 14 THE EXTERIOR OF THE HORSE. Muscular Mechanics. These ideas can be at once applied to muscular mechanics. A muscle which contracts tends to draw its two extremities equally towards its centre. Each one is usually inserted upon a distinct bone. The bones, however, are not all movable to the same degree. Whence it follows that every muscle has a fixed and a movable insertion, the latter being situated upon the bone which is displaced during the contraction. As the muscles of the apparatus of locomotion are voluntary, the animal can at will change a movable insertion into a fixed insertion, and vice versa. In other terms, a muscle, for example, which extends from the head to the arm (mastoido-humeralis) can as well become a motor of the head as an extensor of the arm. It suffices that the other muscles contract in order to fix and render immovable the head or the arm. The multiplicity of the muscular fibres is in proportion to the intensity of the contraction ; their length, on the contrary, agrees with its extent. Or, if preferred, the volume of the muscles gives the measure of force ; their length, that of speed. It is, then, we believe, an error to think that the extent of the contraction of the muscles is not measured by the length of their fleshy portion, but by the length of the fibres which form them. This is only partly true, for in compound muscles, if the fibre be interrupted by aponeurotic or tendinous intersections, if it be shorter than in simple muscles, things occur, so to speak, as if the fibre rep- resented the length of the fleshy body. The extent of the contraction is the result of several distinct actions which are added to one another to determine the total effect. The intersections, therefore, only give greater support to the con- traction of the fibre ; they furnish it with greater resistance to the tractions of weight, for the muscles in which they are encountered, besides their active role in locomotion, are still important passive agents in station. In most instances, in the members especially, the muscles are applied along the length of the bones, and are found, on that account, in conditions very dis- advantageous. Their manifest tendency towards parallelism with the lever-arm seems to have little connection with the theoretic ideas which we have just given, since a large part of their force is regarded as lost for movement. This is of no account, however, and it is easy to determine that this disposition is, on the contrary, most fortunate, whatever may have been said concerning it. Indeed, if the muscle at the beginning of its contraction acts with a defective incidence, this incidence becomes more and more favorable as the contraction progresses, and the muscle will then profit, at the moment its action is most powerful, by the entire quantity of movement already acquired by overcoming the resistance. But if the insertion at the beginning be more perpendicular, the muscular action, instead of acquiring intensity, will gradually lose it, and the movement produced, while overcoming the resistance, will be less extended. On the other hand, the tendency to parallelism determines in the members of animals those slender forms which we know are in accordance with speed. It is certain that the muscular interstices are much more considerable as the mus- cles are more removed from their bony columns and therefore more perpendicular to them. This is observed in animals with massive forms and slow movements. Here, the heaviness of the gait is due to the enormous size of the mass as well as to the feeble degree of the contraction of the muscles. It must not be inferred from this that for speed we should seek absolute parallelism of the muscles with their levers. It must be remembered that this THE LEVER AND MUSCULAR MECHANISM. 15 parallelism is a hinderance to the execution of the initial movement ; hence the utility of the eminences which the bones of the members present, more particu- larly in the vicinity of their extremities. These projections, upon which the muscles are inflected or attached, have the effect of removing them from the bones and increasing the intensity of their action. Such is the role of the great sesamoids, the supra-carpal bone, the olecranon, the coracoid process, the calca- neum, the anterior tuberosity of the tibia, the patella, the trochanter, etc. Such is the advantage presented by the enlarged extremities of the bones-of the members, and such the result of the inclination of the different bones upon each other. These diverse dispositions retain the advantages of parallelism, whilst avoiding the manifest inconveniences at the beginning of the muscular action. Again, the study of the lever teaches us that the paths described by the lever- arms are in direct ratio to their length, since they describe circumferences which are to each other as their radii. If, consequently, one of the forces act upon an arm shorter than another, the arm of the latter will traverse a path much more considerable. 1 In organisms it is very remarkable to find that the lever-arm of the muscles is usually very weak, especially when the latter are charged with the production of speed. As Lecoq 2 judiciously remarks, power acts in this case with much less intensity, but it may become much greater through the multiplicity of the muscular fibres, which, having only to produces a contraction slightly marked, can be disposed obliquely and be much more numerous in the muscle. On the other hand, if the muscles have their insertion very far from the point of sup- port, their contraction, by removing them from this point, deprives the member of its slender form. From what we have said above, a propos of the inclination of the forces upon their lever-arms, it is easy to determine the force utilized at each instant of the muscular contraction. It is clearly seen that, according as a muscle is at the beginning or at the end of its contraction, there is a tendency to an approx- imation or a separation of the articular surfaces. It is said that a muscle is at its moment when its traction is exercised per- pendicularly to the displaced bone ; but a great many muscles cease their action before reaching that position ; they often only commence the movement which is terminated by the intervention of other muscles. This takes place in the flexors of the metacarpus, for example, whose parallelism to the lever-arm is almost complete ; if the flexors of the phalanges did not initiate the flexion of the metacarpus, these muscles could perhaps not produce it by themselves. In all the instances which we have just considered the mobile bone repre- sents a lever upon which we always find the three fundamental points : the point of support and the points of application of the power and of the resistance. The point of support is nearly always situated on a level with the articula- tion with the fixed bone ; this is also the centre of movement. The power is always applied at the mobile insertion of the motor muscle. As to the resistance, it is situated upon the lever, at that variable point where the weight or the obstacles to the displacement of the mobile bone act, whatever they may be. 1 See, for further details, G. Colin, Physiologic compared, t. i. p. 396, 3e d. 2 F. Lecoq, Recueil de medeeine veterinaire, 1843, p. 493. 16 THE EXTERIOR OF THE HORSE. According to the relative position of these three points, we recognize three classes of levers. In the one called the first class (Fig. 7), the fixed point A occupies an inter- mediate position to the two others, P and R. It is called inter-fixed lever. A certain number of muscles act upon this class of lever. It is exemplified, for instance, in the exten- sion of the head upon the neck. The fixed point (oc- cipito-atloid articulation) is always situated, whatever may be the position of the FlG - 7 - head, between the resist- ance (centre of gravity of the latter) and the power (occipital insertion of the muscles of the nape of the neck). The cervical ligament in our larger domestic species also equalizes the weight of the head by an analogous mechanism. It is, however, not correct to consider the head as an inter-fixed lever at the moment of flexion, as some persons think. According to their view, in fact, the obstacles depend on the antagonists (extensor muscles) and the elasticity of the cervical ligament. These would be the elements of resistance, the weight of the head becoming, according to this opinion, an auxiliary of the power (flexor muscles). No doubt it is sometimes thus when the head and neck are elevated, but things are very different when these regions are directed towards the ground. The weight of the head then becomes to the flexors a veritable resistance to be overcome, and the lever is no longer of the first class ; it is of the third, as we will see further on. Besides, in order to understand the action of a muscle well, it is necessary to investigate it as if it alone were attached to the lever, without regarding the manner of existence of the antagonistic ones. In most instances the latter do not oppose any resistance, but allow the former to execute the movement freely. The extension of the forearm, and that of the metatarsus, the femur, the pelvis, the spine, etc., take place through the mechanism of an inter-fixed lever in which the arm of power is, according to the case, the olecranon, the calcaneum, the tro- chanter, the ischial tuberosity, the spinous or transverse apophyses of the vertebra. In the economy the lever of the first class appears to be more particularly reserved for extension. It is also the lever of speed, for the arm of power is never equal to that of resistance : the latter is always much longer. In man, whose standing position is vertical, in whom falling forward is easy, on account of the particular situation of the organs, the lever of the first kind is, with good reason, to be considered as the lever of station. We shall see that in animals it is that of the second class in which this usage can be prefer- ably recognized. In the lever of the second class the resistance occupies the intermediate posi- tion (Fig. 8). The name inter-resisting is applied to it. In this case, whatever THE LEVER AND MUSCULAR MECHANISM. 17 may be the respective positions of the three points, the lever-arm of power exceeds that of resistance, since PA always remains hypothetically longer than RA.. This lever is, then, very truly that of force, but has more disad- vantage concerning the pro- duction of speed, for, the latter being proportional to the lever-arm, the path of the resistance will never be as long as that of the power. Several examples are seen in animals. It is well known that while standing the weight of the body tends to close all the articular angles of the members upon each other. FIG. 8. There are also observed, on the convex side or the summit of the latter, muscles which are opposed to this closing, by acting as levers of the second class. It is thus that the supra-spina- tus, the coraco-radialis, the sub-spinatus, the subscapular, sustain the scapulo- humeral angle. The insertions of these different muscles are all situated a little beyond the articulation, which represents the point of application of the resist- ance to be overcome, whilst the point of support is placed at the articulation of the elbow. It is in the same manner that the extensors of the forearm sustain the humero-radial articulation upon which are transmitted the actions of the weight, that the suspensory ligament of the fetlock maintains this region, that the gastrocnemius and the perforatus muscles of the leg retain the calcaneum, that the middle gluteal muscle prevents the closing up of the coxo-femoral angle. It will be noticed that all these muscles act as levers of the first class when the members do not serve as a support, so that the organism has no need of inter- posing new anatomical dispo- sitions in order to develop force. The same levers adapt themselves with the same powers to different conditions in order to produce, according to the necessity of the move- ment, either force or speed. Finally, a third case pre- sents itself in the relative situation of the three funda- mental points of the lever. It is that in which the power is placed between the resist- FIG. 9. ance and the point of support. This lever is designated the lever of the third class, or inter-puissant (Fig. 9). Here the arm of resistance is always hypothetically longer than that of the power, and the velocity is increased at the expense of the force. Like that of the first class, it can also be called the lever of speed. 9 18 THE EXTERIOR OF THE HORSE. The economy offers numerous examples of this variety. All the flexor mus- cles act as levers of this kind. The large psoas muscle flexes the femur by this mechanism. The point of support is at the coxo-femoral articulation, the resist- ance (the weight of the member) is applied at the femoro-tibial articulation, and the power is exerted at the internal trochanter. The flexors of the leg, meta- tarsus, arm, forearm, metacarpus, phalanges, head, spinal column, etc., act upon levers of the third kind. We are right in saying that this lever is that of flexion in the same manner as that of the first kind is the lever of extension. In the animal mechanism all the levers are not distributed in the same number. The manner of articulation of the bones and the function of the parts demand here the use of the inter-fixed lever, there that of the inter-puissant lever, and elsewhere that of the inter-resisting. We have, however, a right to ask why the organism utilizes two levers of speed, the first and the third class, since one of them may become that of force. We have seen, indeed, that the bones which act as levers of the first kind when the member is raised become the second kind during support, by the simple dis- placement of the fixed point and of the resistance. It cannot be thus for those which act as levers of the third kind. In other words, the lever of flexion can- not be of the first kind ; it belongs especially to the third. For, were it otherwise, we should find in the sinus of the articular angles apophyses analogous to the ole- cranon, the calcaneum, the trochanter, the sesamoids, or the patella, peculiarities destined to substitute the lever of the first class for that of the third. It is not difficult to see that the movement of flexion, already sufficiently limited by the interposition of the muscular masses occupying the articular sinus, would be almost impossible. The presence of these eminences on the opposite side of the locomotory angles does not cause any inconvenience, for the extension is never complete, and, were it so, it would place the two segments in prolongation with each other, which would not limit the normal movement. In flexion it is different ; the concavity of the angles should be free in order that certain points of the movable segment do not meet too soon the fixed segment and therefore limit its displacement. In all the preceding cases we have supposed the muscular action isolated in order to analyze it better. It is, however, never thus. Every muscle which con- tracts to displace a bone is aided in its role by the contraction of one or more neighboring muscles. These latter have the effect of fixing the one of the two segments which should not be moved. Not one of the pieces of the machine is arranged in an immovable manner, since all are agencies to produce movement. It is then important, in order to avoid the discharge of force, that certain ones among them be immovable, and it is on this account that the contraction of a muscle is always assisted by that of a congener. This fact, most of the time diffi- cult to determine, becomes most evident at the time of the production of the effort. Finally, we remark that, if the organism frequently employ the lever, the simplest of machines, in the functions of its locomotive apparatus, this animal lever differs much from the ordinary one and, with still greater reason, from the mathematical. If we apply to it the laws of the latter, we simply arrive at a sufficient approximation of its action without seeking to establish any abso- lute principle. With M. Mignon, 1 we think that in the animal lever the point of support is * Mignon, M6canique animate, in Recueil de mSdecine vt6rinaire, 1841, p. 67. THE INCLINED PLANE. 19 neither invariable nor certain ; the insertion of the forces neither well established nor very precise ; their intensity always approximative. Whatever may be the exactness of the idea which may exist in regard to volume, length, direction, the structure of the muscle, its angle of insertion^ the arm of the lever which it moves, the amount of contractility that is to say, the value of the force itself escapes us. " In the organized machine resistance is only a power disguised alone by the name. It is indeed weight at first, but it is also muscular contraction wJiich opposes and resists the action of the lever. It is an unknown quantity to be overcome by another equally unknown." Let us add that the forces of extension have their maximum of intensity at the beginning of their action, whilst those of flexion have it at the termination. This is explained by the difference of the result which they should produce. The first resist the weight of the body at the same time that they overcome in loco- motion the inertia of the regions situated below them ; the second only have to raise the member to permit it to advance over the ground, and are nearly dis- charged from the role which the first fulfil during station. The insertion of the extensors is ordinarily more advantageous than that of the flexors, because these latter have but to employ velocity against the others, which should, in addition, develop force. CHAPTER IV. THE INCLINED PLANE. THE inclined plane is, with the lever, the other of the two simple machines employed by the organism in the construction of the locomotory apparatus. It is known that in the inclined plane (Fig. 10) a solid, 0, incited by the weight F, is drawn the length of this plane by a force, /, which is cal- culated by the follow- ing formula : /= OF sin F= sin a. In other words, the force/ is the prod- uct of the weight of the body by the sine of the angle of inclina- tion of the plane. The larger this angle becomes, the FIG. 10. more the component / increases at the expense of the other component, Od, destroyed by the resistance of the plane. The articular surfaces represent a multitude of inclined planes which decompose the weight of the mass upon the bony levers and the tendinous and ligamentous cords situated in the vicinity of the articulations. 20 THE EXTERIOR OF THE HORSE. At the superior part of the members the articular surface is a cavity more or less deep. It may be considered as being formed by a succession of inclined planes whose inclination diminishes from the periphery to the centre. It thus disseminates the weight of the body upon the head, which is adapted to it. The latter acts in the same manner a second time, alternating the actions of the mass by disseminating them upon the ligaments at the same time as upon the bones. On a level with the second articulation of the members we find other inclined surfaces ; these surfaces are multiplied towards the carpus and tarsus ; finally, they are found in the articulations of the hand and foot. Thus more and more the weight of the body is disseminated upon the bony columns through the existence of these diverse inclinations, and the volume of the bones decreases in proportion to the efforts which they support. Another mode of dispersion, again very remarkable, is that which M. Mignon l calls the inclined plane of the segment, in contradistinction to the pre- ceding, which he names inclined plane of surface. " In order to establish the existence of these planes in animal machinery," he says, " it is sufficient to observe that in the members the bony segments super- pose themselves by being diversely inclined and by thus forming a series of angles at their reciprocal points of union. As these angles do not become closed, as the action of the weight is one by its direction, that is to say, vertical, and as the oblique segment, immediately inferior, receives this action, the latter is then trans- mitted in the direction of the osseous segment ; and, since it has followed this in- clined segment, it undergoes the influence of this oblique plane which conducts and supports it ; that is to say, it is decomposed into two parts, one of which is perpendicular to the segment, the other parallel to it and follows its direction. "The flexible supports upon which the segments or inclined planes act therefore become one of the elements of these planes. " If we now examine the mechanical dispositions of the support, we find that the weight of the body is dispersed and attenuated upon a series of inclined planes, which receive, decompose, and transmit this weight; that the solid segments, more and more numerous, support that portion of the weight transmitted parallel to the plane and decompose it in their turn ; that the flexible parts sustain like a spring the other portion of the weight perpendicular to the different planes ; finally, that the levers and pulleys favor, aid, or increase the action of these springs which move and extend intelligent forces that graduate and measure in some manner the entire influence claimed by the necessity of the moment. " Such is the mechanical system, as simple as it is ingenuous, which concen- trates or disseminates action, produces and directs it, increases or diminishes it, resists or combats it." These primary ideas being well understood, we may now begin the particular study of the regions. 1 Mignon, loc. cit., pp. 69 et 71. SECTION SECOND. STUDY OF THE REGIONS. 1. DIVISIONS OF THE HORSE. MOST authors who have written upon the exterior, since Bourgelat, have adopted the division of the horse into fore extremity, body, and hind extremity ; others have preferred the anatomical division into trunk and members. All have acted under the influence of three good reasons. Horsemen, with Bourgelat, have only considered the saddle-horse, and have regarded it as a machine under the rider, extending beyond him, in front and behind. For all those who practise horsemanship, the rider in the management of his mount has two resistances to over- come, two parts to direct : the fore part, that is to say, all that part of the horse in front of him, and the hind part, all that which is behind. The body is under him, he feels its action directly, and it cannot escape him. It is not thus with the fore and the hind parts, whose movements are often far from being correlative, and upon which he should fix his attention. The authors who have preferred, contrary to the preceding, the division of the horse into trunk and members, quickly perceived that the division of Bourgelat, whilst applying itself very well to the service of the saddle, becomes defective when applied to the heavy or the light draught-horse. It would be useless to insist upon this point. The contradiction in the terms is still greater when it becomes a question of studying the external conformation of other domestic animals, such as the ox, the sheep, and the dog. We will adopt the following division, because it is more general and more convenient, and because this book is not alone addressed to horsemen. Whatever may be the animal examined, or its service, it may always 21 22 THE EXTERIOR OF THE HORSE, be divided into three parts : the head, the body, and the members ; and the expressions fore extremity and hind extremity may be replaced to advantage by those of anterior quarters and posterior quarters. The head and the body are the most important parts of the animal machinery, for they contain the organs that are indispensable to the maintenance of life. The members, broken columns articulated from space to space, sup- port the trunk and, by their movements, transport it from one place to another. Besides these principal divisions, there are secondary ones ; these are faces or planes which limit the animal in front, behind, above, below, and laterally. The lateral faces, in ordinary language, are sometimes designated in a particular manner. Thus, horsemen often call the left side (mounting side) the near-side, in opposition to the right, which they call the off-side. As it is usually on the left side from which a rider mounts a horse, these expressions are only suitable for the training- horse, and would be out of place in all other cases. Drivers also employ, for the same reasons, denominations which it is well to understand. One who drives draught-horses is always stationed on the left of the team, and it is for this reason that this side is designated under the name of the side of the man, the right being called the off-side of the man. In Paris and in a large number of departments there are reasons for the use of these expressions, but in certain localities, Finistere and the northern coast, for example, they would be void of sense, since men often drive horses on the right side. We have so far only indicated the primary divisions of the horse. Each of them is again subdivided into secondary regions, which we have consigned to the following synoptical table as well as to the explanatory figures which are annexed to it. In order to facilitate for persons little familiar with dissection a knowledge of the summary anatomical description which accompanies each region, we have, by guiding the artists in the exact representation of the forms of the horse, reproduced Figs. 16, 17, and 18, indicating the various structures. In fact, all the prominences bony, ligamentous, tendinous, and muscular which exist under the skin and may become apparent on the exterior are illustrated here. STUDY OF THE REGIONS. 23 TABLE OF THE REGIONS. 1. HEAD (17 regions). Anterior Face. Posterior Face. Lateral Faces. Inferior Extremity. Superior Extremity. 1. Forehead. 2. Face. 3. Extremity of the nose. 4. Lower jaw. 5. Intermaxillary space. 6. Chiii. 7. Ear. 8. Temple. 9. Supra-orbit. 10. Eyebrow. 11. Eye. 12. Cheek. 13. Nostrils. 14. Mouth, a. Lips. 6. Teeth, Gums. c. Bars. d. Lingual canal. e. Tongue. /. Palate. 15. Poll. 16. Parotid re- gion. 17. Throat. 2. BODY (20 regions). Superior ] Face. nferior Face. Lateral Faces. 8. Ribs. 9. Flank 10. Groin. Anterior Extremity. Posterior Extremity. Genital Organs. 1. Neck, 6. 5 Mane, Forelock. 7. A 2. Withers. 3. Back. 4. Loins. 5. Croup, Haunch. [iphoid region, .bdomen. 11. Chest. 12. Interaxilla. 13. Axilla. 14. Tail. 15. Anus. 16. Perineum. Male. 17. Testicles and envelopes. 18. Sheath and penis. Female. 19. Vulva. 20. Mammae. 3. MEMBERS (16 regions). Anterior. Posterior. Regions Common to the Two Members. 1. Shoulder. 2. Ann. 3. Elbow. 4. Forearm. 5. Knee. 6. Thigh and buttock. 7. Stifle. 8. Leg. 9. Hock. 10. Chestnut. 11. Canon and tendons. 12. Fetlock. 13. Footlock and ergot. 14. Pastern. 15. Coronet. 16. Foot. 24 THE EXTERIOR OF THE HORSE. c ^ X f-l! 1 J u I STUDY OF THE REGIONS. 25 i " FIG. 12. Regions of the horse seen in front. FIG. 13. Regions of the horse seen behind. 1. Ear. 2. Forelock. 3. Forehead. 4. Supra-orbit. 5. Eyebrow. 6. Eye. 7. Face. 8. Extremity / of the nose. 9. Nostril. 10. Superior lip. 11. Shoulder. 13. Neck. 14. Chest. 15. Interaxilla. -16. Axilla. 17. Forearm. 18. Knee. 19. Canon. 20. Fetlock. 21. Pastern. 22. Coronet. 23. Foot. 24. Ribs. 1. Mane. 2. Neck. 3. Withers. 4v Croup. 5* Tail. 6. Thigh. 7. Buttock. 8. Cord of the hock. 9. Point of the hock. 10. Hock. 11. Canon. 12. Fetlock. 13. Coronet. 14. Foot. 15. Flank. 16. Ribs. 12. Point of the shoul- '^25. Hollow of the flank, der or of the arm.^86. Haunch. 26 THE EXTERIOR OF THE HORSE. 19 20 FIG. 14. Regions of the horse seen laterally and in front. 1. Neck. 2. Jugular gutter. 3. Withers. 4. Breast. 5. SMTmlder. 6. Angle of the shoulder. 7. Arm. 8. Axilla. 9. Elbow. 10. Forearm. 11. Knee. 12. Canon. 13. Fetlock. 14. Pastern. 15 Coronet. 16. Foot. 17. Back. 18. Loins. 19. Croup. 20. Tail. 21. Haunch. 22. Flank. 23. Ribs. 24. Thigh. 25. Stifle. g 26. Abdomen. -, 27. Leg. - 28. Hock. 29. Canon. 30. Fetlock. 31. Xiphoid region. STUDY OF THE REGIONS. 27 FIG. 15. Regions of the horse seen laterally and behind. 1. Shoulder. 2. Point of the shoulder. 3. Arm. 4. Elbow. 5. Forearm. 6. Chestnut. 7. Knee. 8. Canon. 9. Fetlock. 10. Pastern. 11. Coronet. 12. Foot. 13. Withers. 14. Back. 15. Ribs. 16. Flank. 17. Haunch. i ' V Thigh. -r fe Croup. 20. Buttock. 21. Tail. 22. Stifle. 23. Leg. 28 THE EXTERIOR OF THE HORSE. STUDY OF THE REGIONS. 29 .s s CJ it i If n If & "a oj e r3 11 ft 52 **5 5 i ' !ij. i|||iini ?3fi'T tsf f f "2 1 s be .2 3 "^ ! -5 CO X ~ 0> QJ 5> 3 8 2S^ H << O oi | I II < r-l I 8 aa^ a fi 85 og II O < sils^iin xs^xxi^^S^ ^^WOOWO<>5 HH 02 03 CD O c4 eo TJI" irj to sS 3 j 3 JS Iliflipj >CS3|3 ' H C -" 'siillS'sli SftftS^g^bO^^n, isaj^fsslaii co o> d i-I c 30 THE EXTERIOR OF THE HORSE. FIG. 17. Superficial structures viewed in front. FIG. 18. Superficial structures viewed from behind. 12. Sterno-maxillaris. 13. Mastoido-humeralis. 23. Short extensor of the forearm. 31. Anterior extensor of the metacarpus. 32 bis. Sterno humeralis. 34. Anterior extensor of the phalanges. 37. Oblique extensor of the metacarpus. 44. Anterior portion of superficial gluteus. 47. Lateral extensor of the phalanges. 49. Posterior portion of superficial gluteus. 50. Middle gluteus. 51. Semi-tendinosus. 52. Femoral biceps. 54. Gastrocnemius. 55. Deep flexor of the phalanges. 56. Cord of the hock. SOME DEFINITIONS. 31 * . 2. SOME DEFINITIONS. In the language of the exterior, certain expressions are often em- ployed whose signification should be exactly known. They are the following : Beauty, Defect, Blemish, Vice, Fault. A. Beauties. Beauty, says Bourgelat, resides in the fitness and the relation of the parts. This definition is incomplete, for it refers only to the proportions of the whole and excludes those of the parts taken sepa- rately. Indeed, it may be that the general harmony in a horse is defective, although some of the parts are absolutely beautiful; the whole may be composed of elements badly arranged, notwithstanding that certain of them are not incompatible in subjects of the best conformation. A more precise sense should therefore be attached to the word beautiful, and we should assert that it indicates the perfect adaptation of the organ to its function, or of the subject to the service for which he is destined. It is not that which pleases the eye, as is often under- stood by persons ignorant of these kinds of study, but that which is 'qualified as fit by the connoisseur, the competent man. Beauty is therefore synonymous with fitness. It is seen, then, that a beautiful region is a good region, a beautiful horse is a good horse, the beauty of the whole results, as Bourgelat says, from the beauty and reciprocal fit- ness of all the parts. One of these may be beautiful without the whole possessing that quality. This acceptation of the word beautiful is applied generally as well as particularly, and it is the only one which should be accepted when the word is employed. There is still another distinction to be established among the beauties : some are absolute, others are relative. Absolute beauties are always sought for whatever may be the ser- vice, the saddle, or light or heavy traction. A spacious chest, large articulations, dense and voluminous muscles, regular equilibrium, and powerful attachments are absolute beauties to be exacted indiscrimi- nately from all horses, for these characters indicate the strength and energy necessary for all services. Relative beauties, on the contrary, denote a specialization for such and such a service. Thus, we prefer largeness of the chest, massive shoulders, voluminous muscles, short, vigorous members, a body close to the ground, wide loins, etc., in the slow and heavy motors which 32 THE EXTERIOR OF THE HORSE. must overcome resistance by the mass and the power of their effort ; whilst we seek a more elevated and narrower body, a longer neck, a light head, long bones, in a word, a smaller mass and more subtle and extended movements, for the rapid motor. These are beauties rela- tive to these two kinds of utilization, which would become prejudicial if instead of being applied to one they were applied to the other. B. Defects. The word defect is, in its etymology, the opposite of beauty. It characterizes the want of adaptation of the thing to the end for which it is destined. Defects are absolute, relative, congenital, or acquired. Absolute defects are causes for the rejection of the horse, for they are injurious to every kind of utilization. Thus, a flat costal region lessens the capacity of the chest, flat feet render the application of the shoe difficult and expose the foot to contusions of the heels and the sole; a retracted abdomen indicates a capricious appetite; slender members are soon ruined ; small articulations diminish the extent of the movements ; unstable equilibrium predisposes to falls, to excessive use of the members, etc. These are so many absolute defects. On the contrary, defects are relative when they only injure the em- ployment of a horse for a determined service. A concave back is defective for the pack-saddle ; a croup too oblique and a very large chest will not be suitable for the rapid gaits, whilst they are not preju- dicial in the draught-horse ; the same is true of the low withers and *,he high withers, the horizontal croup and the double croup, etc. It is apparent, then, from these examples, that what is a beauty for one service may become a defect for another. Congenital defects are those which the horse possesses at birth ; acquired defects, those which are the result of his utilization. A knee-sprung horse that is to say, one whose knee is naturally displaced forward is affected with a congenital defect; whilst, if this lefect be the result of usage, he is said to be possessed of an acquired defect. Most defects are malformations which the animal possesses at birth, and are therefore of a congenital nature ; however, there are a large number which he acquires through work. C. Blemishes. It is difficult to give a good definition of the word blemish, be- cause the first condition to fulfil in order to define a thing is that the thing itself be defined in the literal sense of the word. At this present SOME DEFINITIONS. 33 time the number and nature of the blemishes are far from being deter- mined. Nothing is more absolute, nothing more relative ; all depends upon the idea which is formed of them. The words blemish, vice, and fault are very often employed synony- mously Avhen applied to the horse. They appear, however, to have a particular signification. Thus, by the term blemish is designated a cause of depreciation superficial and apparent. Vice and fault seem rather to convey in themselves something concealed. Among the numerous definitions which are given of a blemish, that of Littre seems to us to be the most complete : " A blemish is a defect of whatever origin, pathological or otherwise, which has its seat in the skin or the subjacent parts, and which diminishes more or less the value of the horse." As the word defect has another sense in the exterior ; as, besides, it is of little importance to explain the variety of the origin of blemishes, since this origin may or may not be pathological, we will modify this definition in the following manner : A blemish is every apparent trace of depreciation having its seat in the skin or in the subjacent tissues. This trace need not be persistent. A horse may indeed be blemished to-day and not be so eight days hence. A very slight fall upon the knees sometimes leaves an immediate trace which then blemishes the subject, while oftentimes soon afterwards nothing is visible. However it may be, we add that most usually the name blemish is given to cicatrices, tumors resulting from accidents, operations which the animal has undergone, or different diseases which have left apparent lesions. Let us give some examples. A horse one of whose articula- tions has been cauterized is blemished. A horse which presents en- largements around the hock is blemished. The same thing follows when blisters are applied to the walls of the thorax, and the hairs are not replaced at the place of their application. A horse which after having been bled has contracted an inflammation of the jugular vein, with a consecutive obliteration of the latter, is a blemished horse. Blemishes, as may be conceived, are of more or less gravity, and diminish, on that account, the value of the animal which possesses them. There are some to which no importance is attached. We will return to them in the examination of the regions. D. Vices and Faults. These two expressions have not always the same meaning in the language of the exterior. In certain cases the word vice is synonymous with disease or defect, as is seen, for example, in the first article of the 3 34 THE EXTERIOR OF THE HOUSE. law of August 2, 1884, which treats of the sale and exchange of domestic animals. This law gives, in fact, the enumeration of all the vices, faults, or diseases reputed redhibitory, that is to say, which cause a cancelling of the sale or exchange. In other cases, vice results from the bad character of the animal or from his imperfect educa- tion. A horse which bites, strikes, rears, and pulls backward without being induced to do so, is a vicious horse. Generally there exists a certain gradation between vices and faults. To the word vice is usually given the sense of a serious moral imperfec- tion ; to the word fault, that of a slight moral imperfection ; finally, to the word defect, that of a physical deficiency more or less serious. We repeat, however, that these three expressions are often employed in the same sense in ordinary language, although they are, as we have just seen, quite clearly defined. t PART I. THE HEAD. Divisions. Situated at the anterior extremity of the trunk, the head represents a resistance placed at the extremity of the arm of a lever formed by the neck, a resistance whose relative situation, on ac- count of the extensive movements which it executes, has a great influence in changing the position of the centre of gravity. Studied as a whole, it presents for consideration four faces, a superior extremity, continuous with the neck, and an inferior, occupied by the oral opening. Each one of these primary divisions is subdivided into a number of regions enumerated in Fig. 19. Faces. 1st. The anterior face presents successively, from above to below, the forehead, the face or nose, and the extremity of the nose. 2d and 3d. The lateral faces present the ear, the temple, the supra-orbit, the eye, the masseteric region, the cheeks, and the nostril*. 4th. The posterior face offers the branches of the inferior max- illa, the intermaxillary space, and the chin. 5th. Inferior Extremity. This is entirely occupied by the mouth, THE HEAD. 35 which comprises several secondary regions, namely, the lipSj the teeth, the gums, the bars, the lingual canal, the tongue, and the palate. 6th. Superior Extremity. It comprises the structures inter- mediary to the head and neck : above, the poll or nape ; below, the throat or pharyngo-laryngeal region ; on each side, the parotid region. Such are the different regions of the head, which we will examine presently. 13 1. Mouth. 2. Superior lip. 3. Inferior lip. 3 bis. Chin. 4. Extremity of the nose. 5. Nostril. FIG. 19. 6-6. Face. 7. Forehead. 8. Inferior maxilla. 9. Cheeks. 10. Eye. 11. Supra-orbit. 12. Temples. 13. Ear. 14. Parotid region. 15. Throat. 16. Neck. 36 THE EXTERIOR OF THE HORSE. CHAPTER I. ANTEKIOR FACE OF THE HEAD. A. The Forehead. Situation; Limits; Anatomical Base. The forehead is that symmetrical region which occupies the superior part of the ante- rior face of the head. It is limited above by the external occipital pro- tuberance and the poll; below by the face; 1 on each side, passing from above to below, by the ear, the temple, the supra-orbit, and the eye. it is partly concealed by a tuft of hairs, the forelock, floating over its surface. It has for its osseous basis the anterior reflection of the occipital bone and the corresponding portions of the frontal and the parietal bones. On each side of the median line, where the frontal bone is directly covered by the integument, are the temporal fossae, occupied by the temporal muscles, separated from the skin by the external and internal temporo-auricularis muscles. Whatever may be the general form of the forehead, there always exists over the temporal fossaa a convexity of variable volume which is due to these muscles ; for the remainder of its extent the region is almost perfectly plane. This region should be examined in relation to its width and its direction. The width of the forehead is an absolute beauty. This is an incontestable fact upon which all are in accord, but to which authors have very often given false interpretations. Most writers exert them- selves to demonstrate that this width is in relation with the intelligence, and deduce from this the indication of its beauty. That this assertion may be established it is necessary to prove : 1st, that the width is in direct relation with the volume of the encephalon ; 2d, that the volume of the latter is proportional to the development of the intelligence. Relative to the first proposition, we should not forget that the frontal diameter depends upon the volume of the surrounding muscles as well as upon the amplitude of the frontal sinuses, filled w r ith air and comprised in the thickness of the cranial parietes. We may even suppose that in most instances it is the resultant of both causes united, and, above all, of the latter, rather than of the actual capacity of the cranial cavity. What, then, becomes of the interpretation given above ? Let the reader draw his own conclusion. Concerning the second assertion, its explanation will be of but little 1 On a line connecting the internal canthi of the eyes. (Harger.) ANTERIOR FACE OF THE HEAD. 37 more consequence. It is true that in the animal scale the development of the encephalon is in relation with that of the intelligence ; but we are not justified to conclude with the positive assertion, that in isolated individuals of the same species this relation is still constant. Con- tradictory observations against the argument are numerous in man, in whom the facts have been well studied. In the horse, such seem to be the facts by the concurrence of the authors who have adhered tothis theory. Vallon 1 reports that at the great cavalry school at Saumur, where large numbers of vicious and unyielding horses from the army are sent, there are many which, compared with others, are not deficient in the transverse measurement of the forehead. The intelligence, therefore, is not in constant relation with the width of this region. Some subjects, without doubt, are more endowed with this faculty than others ; but it is a fact which can only be proved by following the animals in their future career. Among the Arabians the forehead is regarded as one of the four principal characteristics of the horse. This maxim is true, but for reasons very different from those which they have invoked. Again, the forehead should be wide because its transverse develop- ment indicates that of the temporal muscles and of the frontal sinuses, dependencies of the respiratory apparatus. Theoretically, a strong muscularity of a certain region is always an absolute beauty, for not only does it indicate a great aptitude for the execution of its par- ticular function, but it is also a sign of muscular puissance of the loco- motory system in general. For analogous reasons a spacious frontal sinus is to be sought, as the dimensions of one organ are proportional to those of the other organs in the same organic apparatus. From the principle that the function makes the organ it will follow that the more developed it be the more perfect will its function be. It is for this reason that spacious sinuses are an absolute beauty, and not, as Merche 2 thinks, because their object is " the exaltation of the sense of smell." The olfactory cells exist not in the mucous mem- brane of the sinuses, but in the pituitary membrane along the course of the first pair of encephalic nerves. In the young animal, as the foal and the colt, the forehead is very prominent, from the fact that the sinuses have not acquired the same capacity that they will have, from the absorption of bone, as the animal advances in age. 3 1 Vallon, Cours d'hippologie. t. i. p. 306. 2 Merche, Nouveau Traite des formes exterieures du cheval, p. 15, Paris, 1868. 3 The vertical diameter of the forehead is the distance between the external angle of the eye and the base of the corresponding ear; the transverse diameter is the distance from the base 38 THE EXTERIOR OF THE HORSE. The direction of the forehead is closely related to the general form of the head, and varies with the race. It is straight when its surface is rectilinear in every sense ; concave when it is depressed in its inferior portion ; convex when the profile is arched from above to below. These diverse forms designate the head as square, flat, arched, or hare- faced. We will return to this a propos of the general form of the head. The form of the forehead is sometimes modified by the presence of small eminences known under the name of horns, from their analogy with similar appendages observed on animals of the bovine species. The horses which present this anomaly are rare. They are called harned in ordinary language. 1 We will study, in the article on the robes, the peculiarities relative to the color and disposition of the hairs of the forehead. Diseases and Blemishes. The most common lesions of this region are cicatrices and excoriations resulting from falls, blows, and other traumatisms. Among other affections more rare and more serious are tumefactions which result from diseases of the frontal sinuses. Sometimes cicatrices are situated on the middle or inferior part of its surface to either side of the median line, indicating that trepanning has been practised, with a view of giving exit to pus contained in the sinus. When these are observed, it is necessary to complete our examination by that of the nasal mucous membrane and the submaxillary lymphatic ganglia, because an insidious purulent collection of the sinuses may be a complication of glanders. Merche, 2 following Bourgelat and many others, mentions a fraud sometimes committed by horse-dealers attempting to mate horses intended for sale. It con- sists in producing a white coloration in the region of the forehead by cauterizing the skin with a hot iron or with boiling water, etc. The hairs will soon become exfoliated and be replaced by those of a white color. This artifice can be easily detected by the fact that in the centre there is a denuded spot around which the hairs are less numerous than in the surrounding parts. (Bourgelat.) The proof of such a deception is much more detrimental to the reputation of those who employ it than to the value of the animals on which it is practised. B. The Face or Nose (Fig. 19). Situation ; Limits ; Anatomical Base. The face is a sym- metrical region situated on the anterior surface of the head, limited above by the forehead, below by the extremity of the nose, and on each side by the eye, the cheek, and the nostril. of one ear to that of the other. Their relative development gives three classes of foreheads 1. Brachycephalic (square-headed), when the two measurements are nearly or quite equal: it includes the Aryan, African, Irish, and English (shire) horses ; 2. Dolichocephalic (long-headed), When the vertical diameter is in excess, as in the Belgian, Frisian, German, and Percheron races; 3. Mesocephalic, which is intermediary between the two preceding. (Harger.) 1 A. Goubaux, Note sur les chevaux cornus, in Comptes rendus de la Socie'te' de biologic. 1852, p. 25. 2 Merche, Nouveau, Traite des formes ext6rieures du cheval, p. 16. ANTERIOR FACE OF THE HEAD. 39 The bones entering into its formation are the nasal anteriorly, and the lachrymal, superior maxillary, and incisive laterally. Three pairs of muscles occupy the lateral moieties, the supermaxillo-labialis, 1 supernaso-labialis, and inferior palpebral or lachrymalis. The study of this region is very interesting, because it circum- scribes the nasal fossae, whose development is always in direct relation with that of the respiratory apparatus in general. A wide transverse diameter of the face is therefore its first condition of beauty as well as of utility. The face is divided into three regions, a middle and two lateral. 1. Middle Region. This must be studied as to its direction and its width. a. The direction or form of the face or nose gives to the head particular names. Thus, when it is straight or rectilinear from above to below, the head is called flat or square. When it is convex in the same sense, the head is designated as having a ram's nose or a Roman nose, if the con- vexity be limited to the face ; when the convexity extends to the fore- head as well as to the nose, the head is arched. Finally, when it is concave in the middle of its length, the head is likened to that of a rhinoceros, and is also called camel-nosed. The various forms may be congenital or acquired. The latter are due to pressure on the nasal bones from the improper employment of the nose-band of the bridle or the halter. Fortunately, this does not interfere with the capacity of the nasal fossae, which are as capacious as in natural conditions. It will be otherwise, however, if this confor- mation be occasioned by fracture of the nasal bones, as we shall see further on. Although the straight form or square head is the most agreeable to the eye, the other forms of the face do not imply anything derogatory to the development of the respiratory apparatus. 6. The width of the middle region can be easily determined by examining its anterior surface. The width is in all cases an index of the respiratory capacity, and should be in proportion to that of the fore- head to preserve the harmonious relation of the integral parts. We cannot oppose too strongly the erroneous teaching of some authors who regard a convex face, under the pretence that it is narrow, as a predis- 1 This muscle, covering the maxillary sinuses below the eye, can be easily outlined. Its external border is separated from the maxillary spine, with which it is almost parallel, by a space about twenty-five centimetres in width. This space should be selected for trepanning, so as not to injure the muscle. (Harger.) 40 THE EXTERIOR OF THE HORSE posing cause of roaring. This affection does not have its seat in the nasal fossae. Narrowness of the face is an absolute defect. 2. Lateral Regions. The lateral divisions present but little of importance. We will observe, nevertheless, that they do not present altogether the same conformation at different periods of the animal's life. Thus, they are more prominent in young horses, because the molar teeth are more deeply implanted into the alveoli of the superior maxilla ; as age advances and the teeth are continually worn, the latter are pushed from their sockets, and these regions appear more concave. Diseases and Blemishes. The blemishes of the face are : 1. Deformities consequent to fracture of the nasal bones from traumatisms received by the parietes of this region. These fractures are rare, not only because the bones themselves possess a marked degree of resistance, but also because the elasticity of the air contained in the nasal fossae to a great extent breaks the momentum of blows received upon their surface. Nevertheless there is danger of producing, either by the displacement of the bones or the consequent forma- tion of a callus, a serious obstacle to the free passage of the air during ordi- nary respiration and particularly during exercise. Other deformities may exist upon the lateral parietes of the face. These are tumefactions which result from a chronic lesion of the mucous membrane of the maxillary sinuses, due to necrosis of a tooth or other alterations of a diverse nature, whose gravity varies with the cause. 2. Traces of Cauterization. At the present time cauterization of the face is seldom practised. The Arabs employed it in the treatment of strangles and benign affections of the superior respiratory passages. With these exceptions, such blemishes indicate that the animal has been or is still suffering from a grave disease of the nasal cavities. 3. Cicatrices which are the result of traumatisms, excoriations, or thicken- ings of the skin caused by the halter or bridle ; finally, cicatrices of an angular or semicircular shape, arousing the suspicion that the maxillary sinuses have been trephined. These last are situated within the maxillary spine towards the internal angle of the eye. When any of the blemishes enumerated are present, it is necessary to com- plete our examination by a minute inspection of the nasal sinuses, the molar teeth, and the subrnaxillary lymphatic ganglia. C. Extremity of the Nose (Fig. 19.) Situation ; Limits ; Anatomical Base. The extremity of the nose is situated at the inferior extremity of the face, between the nostrils and above the superior lip. Anatomically it comprises for its base the anterior extremity of the septum nasi and the comma-shaped cartilages which encircle the internal alse of the nostrils. The external face of the latter is covered by the transversalis nasi muscle, which is separated on the median line from the fine integument of this region by the terminal tension of th maxillo-labialia muscle. LATERAL FACES OF THE HEAD. 41 All authors who have described this region have confounded it with the superior lip, whose organization is entirely different. They have, therefore, erred anatomically in saying that it has an extensive nerve- supply, and physiologically none the less seriously in considering it as the principal organ of touch in the horse. The superior lip fulfils the latter role. It follows from this that we will describe neither beauty nor defect of this region, excepting that it should be large as an index of the respiratory functions. It is more important to assure ourselves that it is exempt from blemishes. When they exist, they are nearly always the result of falls which the animal has received. It is necessary, then, to examine with care the state of the incisor teeth, the lips, the gums, and the plumb-line of the extremities, to determine as nearly as possible whether the blemishes resulted from an accident or from a weakness of the fore limbs, the effect of usage. They are never produced by the application of the twitch, a means of torture employed to divert the attention of the animal, and which can only be placed upon the superior lip, whatever precaution in this respect be taken. CHAPTER II. LATERAL FACES OF THE HEAD. A. The Ear (Fig. 19). Situation ; Limits ; Anatomical Base. The ear is situated at the superior extremity of the lateral face of the head, to one side of the forehead and the dependency of the mane known under the name of forelock, in front of the poll, above the parotid gland and behind the temple. Anatomically, this region is easily visible, and has for its base the conchal and scutiform cartilages. These give attachment to ten pairs of muscles which endow the ear with movements either general or partial. The former carry it backward, outward, forward, inward, and rotate it on its adipose cushion. The latter (mastoido-auricularis) are destined to move the concha so as to adjust the volume of air in the auditory chamber (hiatus) to sounds of different intensities. Diverse beauties are recognized in this organ which are depend- ent upon its length, thickness, situation, direction, and movements. 1. Length. As Bourgelat has remarked, some prefer a long ear, 42 THE EXTERIOR OF THE HORSE. others a short one. He adds, with much prudence, that good judgment does not approve of an excess of length, and that this organ, being an integral part of the head, should be in proportion with it. It is a fact worthy of remark, that horses in which they are short are usually energetic and courageous. We must also add that small ears diminish the apparent size of the head, render the physiognomy more pleasant and expressive, and brighten the eye. In this respect the Aryan horse has greatly influenced the English thoroughbred ; the Boulonnais, the Flemish ; the Irish, the Percheron, etc. 2. Thickness. The thickness of the ear denotes the quality of the race and of the subject. This is indicated by several other organs which in addition reveal clearly his origin. When the skin of the concha is thick, and garnished on the inside with numerous long hairs, when the subcutaneous connective tissue is abundant and obliter- ates the blood-vessels and nerves, w r e have evidences that the subject is common and lymphatic. A concha small, firm, and elastic, covered by a skin fine and adherent, with fine and scanty hairs in the interior, and blood-vessels well outlined, characterizes an animal of distin- guished ancestry. This is so well known to horse-merchants that they never fail to tamper with the hairs of the ears of common horses in arranging their toilet prior to offering them for sale. 3. Situation. The situation of the ear merits consideration. Its distance to one side of the median line, though dependent in part upon the development of the muscles of this region, allows us to appre- ciate, to a certain degree, the width of the cranial cavity. If this separation gives more expression to the head and presages greater intel- ligence, it is nevertheless necessary to guard ourselves against an error of which we have spoken, in according to this character more impor- tance than it deserves. The same argument applies to ears situated too high ; they have an unpleasant effect on the eye and are often an index of a timid and sulky disposition. 4. Direction and Movements. It is considered a mark of beauty if a horse freely directs his ears to an angle of about forty- five degrees with the axis of the head. It is thus that they present themselves in active and energetic subjects : if, besides, they are short and well placed, they are designated as bold or cunning. Ordinarily they are moved in various directions to receive sound- waves, by means of w r hich the animal obtains a direct knowledge of certain conditions of the exterior. Animals in which the ears are motionless are sluggish and indolent or, what is more serious, suffer from a variable degree of deafness. LATERAL FACES OF THE HEAD. 43 Let us refer to certain movements which have not been considered. These are forward and backward oscillations of the ears of some horses during work, and particularly during laborious efforts. At each step or at each effort the animal carries the ears quickly forward, then back- ward to their primitive position, and repeats this action during the con- tinuance of the work. We know of no appropriate expression to qualify these singular oscillations. En resume, the ear is beautiful when it is short, directed forward, well situated, clean, fine, covered by a thin and adherent skin, with few hairs in the interior of the concha. Defects. Ears long, thick, and transversely horizontal designate a horse as being lop-eared. This ungraceful carriage does not neces- sarily detract from the good qualities of the animal. There are many lop-eared horses none the less excellent for service. Nevertheless this defect is more common in lymphatic horses than in those of the finer races. We speak also of horses whose ears are held in a horizontal di- rection and undergo, during locomotion, alternate elevations and de- pressions. It has been said of such, more picturesquely than properly, that they limp at the ear. This peculiarity may exist on the right, 011 the left, or on both sides simultaneously. When the ear is thick, large, and decidedly pendulous, overhanging the parotid region, it is called swine-ear. This defect is no more grave than the preceding, but it is more unpleasant to the eye. The ears are restless or uncertain Avhen the animal keeps them in continual motion in the stable as well as during exercise. This is an evidence of a timid nature, impaired vision, or even total blindness. It seems that in the last two instances, as H. Bouley l has said, the animal endeavors to compensate for the loss of vision by turning the auditory apparatus in various directions ; he endeavors to see by the sense of hearing. In the language of horsemen, horses are skittish if they worry and fret at the least noise when they are driven into such or such a place in the stable or made to execute certain movements ; it is often remarkable. Finally, some horses carry the ears backward against the superior border of the neck. It is evidence of a bad disposition and an inclina- tion to strike or bite when approached. Blemishes. The blemishes of this region are numerous. 1st. It is quite common to observe draught-horses whose ears are 1 H. Bouley, Maison rustique, t. ii. p. 195. 44 THE EXTERIOR OF THE HORSE. lacerated. They may become deformed, thickened, and acquire a faulty direction. Fractures of the conchal cartilage result ordinarily from blows inflicted by brutal drivers ; they have no serious consequences. 2d. At the present time horses with the ears cropped in the middle of their length are almost unknown. We have met with only two instances. It appears, however, that this was the custom during the last century. Horses which had undergone this operation were called crop-eared. If at the same time the tail had been amputated, they were designated by the term docked (J. B. Huzard). Yallon * reports that this mutilation was formerly common in Algeria, and was em- ployed by the Arabians in their military expeditions to establish proofs of ownership. Under other circumstances, amputation of the ears is sometimes effected by the application of the twitch, most often by brutal farriers, upon horses difficult to shoe or to dress. It will not be difficult to convince the reader of the danger which the employment of such procedures may occasion. 3d. It is not less rare to meet horses whose ears are split. This incision was made upon the left ear of cavalry horses under eight years of age, discharged from the French army. The purchasers did not delay to unite the two flaps. When the incision had existed for a long time, they freshed the edges with a cutting instrument and united them. Nothing more than a cicatrix persisted afterwards, which was often concealed by the hairs. In Algeria, says Vallon, 2 as in the states of the Mussulmans, it is the custom under certain circumstances to split the ears of colts. We can therefore purchase, without fear, such horses as have been subjected to the operation. This is also practised on the Western prairies of the United States as a brand of ownership. 4th. We sometimes observe at the base of the ear denudations or circular cicatrices which result from the repeated application of the twitch to this region. It is to be feared, then, that the animal has been treated for a disease of long standing which required repeated dressing, or that he is difficult to shoe, harness, etc. Certain horses during the summer, as soon as they begin to perspire, experience violent itching in the interior of the ear, which causes disordered movements of the head. Cleanliness, hygienic precautions, and de- tersive lotions are the remedies for the affection. Let us now consider the fraudulent means employed to hide the defects and blemishes of this region. i Vallon, Cours d'hippologie, t. i. p. 317. 2 Ibid. LATERAL FACES OF THE HEAD. 1st. The simplest and most harmless among them consists in clip- ping" the hairs of the ears. In this part of the animal's toilet, the dealer carefully cuts the long and abundant hairs which exist in a normal state at the entrance of the concha and which act undoubtedly as organs of protection to the auditory apparatus. These hairs are less abundant in horses of the finer races, as stated above. It is also in- tended by this procedure to give lightness to the head, fineness to" the ear, and distinction to the animal, characteristics which do not belong to common horses. This fraud for it is a procedure whose object is to deceive the buyer as to the real qualities of the merchandise which is oifered is not easily detected except by those who are experienced with horses. This is so generally resorted to that certain dealers, very honest otherwise, are unwilling to expose horses for sale unless they have been thus prepared. When questioned as to this practice, they respond that, the parts being cleansed with difficulty, the removal of the hairs renders this more easy. We often find on the internal sur- face of the concha a thick layer of sebaceous matter cerumen which becomes irritating, provokes pruritus during the summer, and, at the same time, attracts insects. This material is most abundant in horses whose sanitary conditions are neglected. Particles of fodder and atmospheric dust will adhere to it, against the invasion of which the hairs thus shortened can offer no obstruction. In the army this custom has been abolished. 2d. Another common means is the use of a hood, under the pre- tence of protection from insects. It should always be removed, as it may hide the marks of the twitch, for example, if it be difficult to shoe or harness the animal ; or, again, a leaden ball suspended by a thread and placed in the interior of the ear to quiet nervous subjects. 3d. When the ears are long and pendulous they can be made, by horsemen, to assume a good direction by means of a silk thread which is covered by the hairs of the forelock. Being thus adducted towards the median line, they may entirely hide this defect. 4th. Certain operations were formerly practised upon these organs, whose effect was to straighten them. They are not employed at the present time, but have been abandoned, not because of a moral view, but because they are recognized as being dangerous and inefficient. It is not rare to see horsemen attempt to shorten the ears by means of the ear-cutter. This instrument is a sort of mould composed of two lateral halves, into which the concha is received. Whatever projects beyond the edges of the instrument is carefully removed with a bistoury. We have not included deafness among the defects of the ear because 46 THE EXTERIOR OF THE HORSE. this infirmity is often difficult of appreciation, although it may occasion great inconveniences in animals which are governed by the voice of their master. As M. Richard l remarks, in deaf horses the ears are generally fixed, directed forward or laterally, vainly endeavoring to perceive sound. This attitude, by itself alone, does not permit us to recognize this defect at the time of sale. In most instances it passes unperceived, and is only observed after the animal has been worked for some time. Deaf horses are ordinarily docile, both in harness and in the stable, and respond quickly to all the indications of the bridle and bit. The Arabians, with almost self-love for their horses, urge them with the voice as well as with the hand, and reject those which are deaf as being fit only for the pack-saddle, and of little value as saddle-horses. Nevertheless, it is more prejudicial in draught-horses. Those that are mounted are more easily guided by the action of the bridle. B. The Temple (Fig. 19). Situation; Limits; Anatomical Base. This is a double region, more or less prominent, situated on the lateral faces of the head. It has for its anatomical base the exterior of the temporo- maxillary articulation, and is limited below by the cheek, behind by the parotid region, and in front and above more or less directly by the ear, the eye, and the supra-orbit. The principal qualifications which we seek here are its distinct- ness and its freedom from blemishes. Diseases and Blemishes. Denudations, excoriations, and wounds of this region deserve to be taken into consideration. The first are the result of friction from disordered movements of the head, as in animals tossing themselves about when suffering from colic, vertigo, epilepsy, or grave diseases of the feet, when the animal assumes a prolonged decubitus, etc. The second, on the contrary, are the consequences of severer causes, as traumatisms of various kinds, which may primarily or secondarily open the articulation, allow the escape of the synovial fluid, and produce a fistula. The last accident is serious, the horse being unable to masticate his aliment properly on account of the pain which the movements of the jaws produce. 2 It is not astonishing that an affection of such a nature might be concealed by a hood which covers the ears to protect their interior from foreign bodies and insects. At any rate, the animal should always be un- covered during the examination, and such an alteration of the temple should never escape the attention of the observer. 1 Richard. tude du cheval, 6e M., p. 66. 2 A. Goubaux, Comptes-RendusdelaSoci6t vC'terinaire (seance du 27 avril, 1876). LATERAL FACES OF THE HEAD. 47 This is the region in which the first white hairs, common in old horses of a dark color, make their appearance. It is to be remembered, however, that we may find gray temples in younger horses as well as in colts and foals. C. The Supra-orbit and Eyebrows (Fig. 19). Situation ; Limits ; Anatomical Base. The supra-orbit is an asymmetrical depression situated above the eye, on the side of the forehead, and above the cheek and the temple. This region, which corresponds to the most superficial part of the temporal fossa, is filled with a mass of adipose tissue more or less abundant. It indicates nothing as to the quality of the animal, but it permits us to make an approximate inference of his age. It is a well-known fact that in old horses the supra-orbits become hollow from the absorption of the fat which in the young animal completely occludes them. This fact is not so constant that very much im- portance can be attached to it. Although the first condition does not lessen the real value of the animal, horse-merchants, in order to obliterate these cavities when empty, have endeavored to fill them by a very simple method which, in the majority of cases, occasions no inconvenience. It consists in making a deep puncture into the region with a large needle or the sharp blade of a knife until the connective tissue of the temporal fossa is reached. Having made the incision, the mouth is applied over the opening and the connective tissue is forcibly inflated witji air. (A hollow needle would be more expeditious.) We have seen one instance in which an abscess complicated this operation. To detect this deception, it is only necessary to make pressure with the fingers over the region, which will produce crepitation due to the passage of the air through the connective tissue. Some authors have admitted a region of the eyebrows. Huzard the elder and Merche have absolutely denied their existence. Lecoq * refutes with good reason the latter opinion by remarking that in the foetus the arches of the eyebrows are visible, in a very distinct manner, a little before the remainder of the body is covered with hairs. Later, they are confounded with the surrounding parts and lose, for this reason, all interest from a point of view of the exterior. We will not dwell any longer on this point. 1 F. Lecoq, Exterieur du eheval, 4e 6d., p. 215. 48 THE EXTERIOR OF THE HORSE. D. The Eye (Fig. 20 and Fig. 23). Situation ; Limits. The eye constitutes a double region situ- ated upon the lateral planes of the head, above the cheek and the face, below the supra-orbit, and on each side of the forehead. Anatomical Base. The essential part of the visual apparatus consists of a membranous sphere called the ocular globe, transparent in front, whose interior is lined by a nervous membrane, the retina, sensitive only to luminous rays. It is protected over its greater extent by a deep osseous cavity, the orbital cavity, to the bottom of which it is fixed; in front also by two mobile curtains, the eyelids, which complete the orbit in front and regulatp the quantity of light which should be admitted into its inte- rior. Ten pairs of muscles endow it with various movements ; finally, special organs of a glandular nature lubricate its anterior surface and protect it from the constantly desiccating influence of the atmosphere. Such, in a general way, is the organization of the ocular region. 1st. Essential Organs of Vision, or the Globe of the Bye. This is a membranous envelope, completely closed, whose interior is filled with trans- parent substances of a variable density, known under the generic name of the media of the eye. This sac, most bulging in front, is constituted here by a transparent, thick, and resisting expansion, the lucid cornea, covering one-fifth of its peripheric sur- face. Posteriorly it is composed of three layers, to which are assigned different functions. These are, proceeding from without to within : a. The sclerotic (1), white, sometimes pigmented, 'fibrous, resisting, and thick, which is vulgarly often known under the name of the white of the eye, and which is visible from the exterior by its white coloration around the periph- ery of the cornea whenever the eyelids are separated from each other. Its ex- ternal surface gives attachment to the motor muscles of the eye-globe. Its anterior elliptical opening is closed by the cornea by bevelled edges after the manner of the crystal fitting into the case of a watch. b. The choroid (2), very thin, black, not visible from the exterior, which plays the role of an absorbing surface for an excess of luminous rays, and con- verts the interior of the eye into a veritable dark chamber, into which the images of external objects are received to be appreciated by the retina. This membrane, in front, where it is called the ciliary body, presents numer- ous radiating folds, the ciliary processes, which circumscribe the edges of the crys- talline lens (7). Through the ciliary ligament it gives attachment to the circum- ference of the iris (4), an elliptical diaphragm pierced in its centre by an opening, the pupil (5). The iris and the pupil are visible through the transparent cornea. The former divides the space anterior to the crystalline lens anterior chamber into two communicating compartments, an anterior (8) and a posterior (8') practically obliterated. The coloration of its anterior face is of a yellowish-brown, but it may vary in different subjects ; that of the posterior, on the contrary, is black, due to LATERAL FACES OF THE HEAD 49 the presence of pigment called the " uvea," variable masses of which, called " cor- pora nigra," or " soot-balls," l are sometimes suspended from its edge into the pupillary opening. FIG. 20. VERTICAL SECTION OF THE EYE OF THE HORSE (semi-schematic). 1, sclerotic; 2, choroid ; 3, ciliary processes; 4, iris; 5, anterior compartment, with the aqueous humor; 6, retina; 7, crystalline lens; 8, anterior chamber ; 8'. posterior chamber: 9, pos- terior compartment of the eye, with the vitreous humor; 10, ocular sheath ; 11, tarsal cartilages; 12, integument of the eyelids; 13, conjunctiva; 14. section of the small oblique muscle; 15, lach- rymal gland ; 16, cornea; 17, transverse section of the superior half of the orbicularis muscle; 18. posterior straight muscle; 19 superior straight muscle; 20, elevator of the superior eyelid; 21, section of the orbital arch ; 22, optic nerve; 23, transverse section of the inferior moiety of the orbicularis muscle ; 24, section of the floor of the orbit. c. The retina (6), transparent, very thin and delicate, adherent to the choroid and its dependencies, which is an expansion of the optic nerve, and upon which the impressions of light are directly perceived. Media of Refraction. a. Crystalline Lens (7). This is a bi-convex, 1 These are found in most eyes, and when not excessive, so as to obstruct the light, are not an ursoundness. (Harger.) 4 50 THE EXTERIOR OF THE HORSE. transparent l organ, more convex on its posterior face, and appears behind the pupil. It is closely applied against the posterior face of the iris, and divides the interior of the eye into two great compartments, an anterior (5) and a posterior (9). b. Vitreous Humor (9). It is a transparent, limpid, and gelatinous sub- stance which occupies the whole of the posterior chamber. c. Aqueous Humor (8). The aqueous humor, slightly more dense than water, occupies the anterior chamber (8 and 8 X ) of the eye. It bathes both surfaces of the iris. It is under external as well as internal pressure, and readily escapes when the cornea is perforated. The function of these three media of the eye is to concentrate the rays of light, by refraction, upon the surface of the retina, where they make an image. The lens, being more convex behind than in front, converges them for this reason and brings them to a focus on the anterior surface of the retina. Its relative position is thus necessitated by this function ; if too distant from the retina, the image is formed anterior to the latter and is not perceived by that membrane ; if too close, the rays converge posterior to the retina and the image really would tend to be formed outside of the ocular globe and again is not appreciated by this structure. 2d. Protective Organs of the Eye-Globe. These include the orbital cavity, the eyelids, and the nictitans membrane. a. The orbital cavity is a conical, deep cavity, surrounded by a fibro-osseous wall with an osseous opening in front. Its parietes are formed by the ocular sheath (10), conical and resisting, attached behind to the crest of the orbital hiatus, whose base is attached to the orbital opening and thence prolonged into the eyelids, whose base they constitute. Superiorly, the eye is only protected by the adipose cushion which forms the base of the supra-orbital region. Internally and inferiorly, the orbital cavity is osseous. The opening of the orbital cavity is circumscribed by the orbital process of the frontal bone (21) and a portion of the lachrymal and zygomatic bones (24). We also find on its floor and towards the internal side the lachrymal fossa and the superior orifice of the canal of the same name. 6. The eyelids, distinguished as superior and inferior , are two mobile mus- culo-membranous valves which protect the part of the eyeball exposed to the exterior. Their free border, more curved in the superior than in the inferior, presents the excretory orifices of the Meibomian glands as well as a series of ten- tacular hairs longer above than below, known under the name of eyelashes. The eyelids offer, besides, two commissures or angles, a temporal or external, and a nasal or internal. The external face is covered by an adherent (12) delicate skin provided with numerous short hairs. The internal face moulded on the eye-globe is covered by a delicate mucous membrane the conjunctiva (13) which is very sensitive to foreign bodies. The conjunctiva in the healthy animal is of a rosy color and becomes reflected over the choroid and the nictitans membrane, and is pro- longed into the lachrymal canal. It becomes arrested at the edge of the cornea and its epithelial layer alone covers that structure. At the free border of the eyelids exists a cartilaginous lamina called the tarsus, on which the extremity of the ocular sheath terminates. 1 It sometimes has a bluish color, due to the reflection of the variegated colors at the poste- rior part of the choroid. (Harger.) LATERAL FACES OF THE HEAD. 51 The Meibomian glands, embedded in the deep face of the tarsus, secrete a sebaceous matter which prevents the escape of the tears in a normal state and obliges them to follow the natural passages in reaching the exterior. The orbicularis palpebral muscle approximates the two lids and the levator palpebra elevates the superior ; the inferior is depressed by its own weight. c. The membrana nictitans, or third- eyelid (haw), is a nucleus of very mobile cartilage surrounded by adipose and connective tissue and the conjunc- tiva, situated at the internal canthus of the eye. It becomes continuous with the adipose tissue enveloping the ocular muscles. It has no inherent movements of its own, but mechanically protrudes when the eye is compressed, and liberates the latter from foreign bodies. It glides over the surface of the cornea when the eye is retracted into its orbit, and can be easily rendered visible when the globe is compressed and drawn into the bottom of the ocular cavity. 3d. Apparatus of Lubrication of the Eye. This apparatus com- prises the lachrymal gland (15), situated between the orbital process of the frontal bone and the eyeball. It secretes the tears. These are distributed over the surface of the cornea by the hygrophthalniic canals, which open on the inner surface of the superior eyelid towards its temporal angle, and thence they gain the nasal commissure, where they open through the puncta lachrymalia into the lachrymal ducts. A small tubercle, the caruncula lachry mails, a dependency of the conjunctiva occupying the inner angle of the eye, directs them towards these two conduits, whence they pass successively through the lachrymal sac and the lachrymal canal to make their exit through the orifice on the floor of the nostril, where they are liberated on the exterior. 4th. Apparatus of Locomotion. The movements of the eye are protec- tive and functional. The former have for their object the mechanical protrusion of the nictitans membrane upon the ocular surface by retracting the eye into the bottom of its orbit. It is accomplished by the posterior rectus muscle. The latter elevate, depress, deviate laterally, rotate the eye, and control the size of the pupillary opening of the iris to regulate the quantity of light which enters the eye. Elevation, depression, and lateral inclination of the eye-globe are executed by the contraction of the superior, inferior, external, and internal recti muscles ; rotation, by the superior and inferior obliques, muscles which are physiological antagonists. These muscles are inserted posteriorily into the bottom orbital hiatus and anteriorily on the external surface of the sclerotic. Their anterior insertion can be exposed by making lateral traction on the eye-globe with a tenaculum. Method of Procedure in the Examination of the Eye. Long ago, Bourgelat * bad clearly indicated the precautions to be taken in executing such an examination skilfully. It is, perhaps, needless to recommend that the head should be divested of all harness, more particularly of blinkers, and that the surroundings should be such as not to obstruct the view or communicate abnormal reflections to the eye. The head is turned towards the entrance of the stable, and the eye is carefully inspected in semi-daylight to observe any pathological 1 C. Bourgelat, Traite de la conformation exterieure du cheval, 5e ed., p. 57. 52 THE EXTERIOR OF THE HORSE. alterations. For this purpose the ophthalmoscope may sometimes be used with advantage. Then the animal is taken into broad daylight to see how the eye acts under the influence of the solar rays. To de- termine simply the integrity of vision the following procedure is pur- FIG. 21. Examination of the eye. sued : The observer places himself in front of the animal, strikes the side of the face lightly with the hand, and suddenly withdraws it in elevating it to a level with the corresponding eye. The latter, if vision is not impaired, will suddenly close from fear of being struck. If the sight is impaired or lost, the eyelids remain stationary. This manoeuvre is repeated with the opposite eye. The movements of the hand must not be too forcible, as excessive vibration .of the air may even affect a blind eye, particularly in one-eyed horses. If it be desired to examine LATERAL FACES OF THE HEAD. 53 the conjunctiva, the nictitanous membrane, the lachrymal caruncle, the media, etc., with more care, and the eyelids are not .sufficiently sep- arated, the following manipulation is employed (Fig. 21 and Fig. 22) : Having quieted the animal, one hand is placed upon the face to pre- FIG. 22. Examination of the eye. vent his advancing, or upon the inferior lip, if the head be held too low. Then, with the thumb and index finger of the free hand, the eyelids are. separated and the eye-globe is compressed into the orbital cavity. The nictitans will then protrude and expose a large area of the con- junctiva, and render pathological growths or foreign bodies visible. Beauties of the Eye. Whatever may be the physiological integrity of the eye, its absolute beauty resides in the following phenomena : 1 . Its separation from the median line, which coincides with a wide forehead and a wide nose. 2. Its degree of prominence over the surrounding regions, which 54 THE EXTERIOR OF THE HORSE. indicates a fulness of the ocular cavity and the temporal fossa, the size and development of the muscular system in general, and the amplitude of the field of vision. 3. Its perfect equality with that of the opposite side. 4. Its deep coloration and the intensity of its reflection, a white or pale color being symptomatic of more or less serious diseases. 5. Its freedom from blemishes of the cornea and the transparency of the media. Alteration in these always manifests itself by an opacity and the appearance of abnormal colorations,, whence results a vari- able degree of imper- meability to light. 6. The extent and quickness of the move- ments of the iris, im- mobility indicating complete insensibility of the retina to the im- pressions of luminous vibrations. The pupil should contract in the presence of light, and dilate in darkness, in order to proportion the retinal sensibility to the functional delicacy of this membrane. 7. A mean convexity of the cornea, too much or too little character- izing a myopic, a hypermetropic, and not a normal eye. 8. The black coloration of the pupil, which denotes a perfect trans- parency of the crystalline lens, and indicates the reflection of the black color of the choroid and the ciliary body situated behind. 9. The integrity, fineness, absence of blemishes, and mobility of the eyelids, all other qualities of these organs indicating imperfections and functional impairment. 10. A rosy tint of the conjunctiva, its redness, paleness, and infiltra- tion being symptomatic of a general or local inflammatory state, of a congestive state, or of profound organic debility. 11. The clearness and little abundance of the tears, the dryness of -the eyelids, the large development and good direction of the eye- lashes. 1,2. Finally, the vivacity, changeableness, and frankness of the ex- FIG. 23. Normal eye. LATERAL FACES OF THE HEAD. 55 pression, which denote the energy, the nobleness, and the distinction of the horse. Such are the numerous beauties sought for in this region. Defects. The defects of the eye are not less important to consider. We mention : 1. The small eye, or pig's eye, in which the ocular globe is little developed, the palpebral opening narrow, and the eyelids thick. It accompanies, in general, a lymphatic temperament and a eonimon an- cestry. It is said to be an index of a predisposition to diseases of this region. 2. The concealed eye, ordinarily small and but little salient, but surmounted by a prominent and voluminous eyelid which partly con- ceals it, implies a sullen and treacherous disposition and a natural aggressiveness. 3. The bovine eye, or gross eye, characterized by an excessive con- vexity of the cornea, is very salient between the eyelids, little mobile, ungraceful, and without expression. It is often predisposed to myopia. 4. The hollow eye is seen only in old horses and in those deterio- rated by age and hard labor. It is retracted into its orbit, covered by flabby eyelids, surmounted by a hollow supra-orbit, and often weeping. 5. The circled or bordered eye is one in which a portion of the scle- rotic around the edge of the cornea is visible through the palpebral opening. It is very unseemly. 6. The eyes are sometimes unequal in size; either from excess or deficiency of growth. When this disproportion is not congenital, it is a subject of apprehension, from always being a constant result of repeated attacks of periodic fluxion. The eye which has experienced repeated attacks of this disease is always the smaller. Its function is practically lost. 7. The myopic eye is very convex ; it resembles much the bovine eye, save the volume, which is not exaggerated. It is observed most frequently in young animals, and renders them irresolute and liable to shy. 8. The hypermetropic eye is, on the contrary, not sufficiently con- vex. Such animals as possess it discern very poorly objects which are near, whilst those which are at a distance can be easily recognized. It predisposes them to stumbling and uncertainty of the limbs. 9. A wall-eye is one in which the iris is of a pearly-white color, being deprived of its pigment. Apart from the visual effect, it is none the less excellent functionally. 56 THE EXTERIOR OF THE HORSE. Diseases. The diseases of the eye are numerous and more or less grave. They are : Nuage is constituted by a slight opalescence of the cornea. Albugo is a complete opacity of a variable area. Leucoma is a cicatrix of the cornea, Glaucoma is a greenish coloration of the vitreous humor. It is grave. Cataract is indicated by a partial or total opacity of the crystalline lens. It is a serious affection. Amaurosu or goutte sereine is due to a paralysis of the retina. It may exist only on one or on both sides. Hydropsy is an augmentation of the volume of the globe of the eye due to a hypersecretion of the aqueous humor. Simple ophthalmia is an inflammation of the conjunctiva. Periodic fluxion is a periodic inflammation of the whole eye, which termi- nates in the total abolition of sight by the formation of a cataract after a variable period. Lippitude is an inflammation of the Meibomian glands and the free border of the eyelids. The eye often becomes covered with the secretion of these glands. It is called blear-eye. Trichiasis consists of an inversion of the superior eyelashes against the ocu- lar globe. Encanthis is a hypertrophy of the caruncula lachrymalis. Melanotic deposits may form on the preceding structure ; warts may grow on the eyelids. Onglet is nothing else than an inflammation of the nictitans membrane. 1 Blemishes. The blemishes of the region of the eyes are denu- dations, abrasions, and wounds of the superciliary arches. They are the consequences of injuries received by striking the head against resisting objects, etc., or of diseases, as epilepsy, when the animal falls to the ground or when he strikes his head against a wall during an attack of vertigo. Sometimes they are complicated by fractures of the orbital arches. Under other circumstances, the eyelids become the seat of abra- sions, lacerations, or deformities of their free border, e.g., ectropion and entropion. The deformity which follows periodic fluxion should be taken into serious consideration. It has been observed that the supe- rior eyelid of the eye, after several attacks of this disease, becomes angular, from ocular atrophy, towards the nasal angle, which gives to the palpebral opening a triangular form instead of that of a regular oval. Finally, all abnormal colors of the cornea or the media of the eye constitute blemishes to which we must give the most serious prognosis. 1 1 have often, in practice, met with eyes affected with strabismus, external, internal, and oblique. This was easily remedied by the simple section of the antagonistic muscle. (Harger.) LATERAL FACES OF THE HEAD. . 57 Among these blemishes, many are the symptoms of grave diseases of the ocular structure. These diseases have too often for their consequence the destruction of one or even of both eyes. The animal is then suffering from par- tial or total blindness. Generally attempts are made to conceal this infirmity, and sometimes we meet with horses offered for sale, provided with an artificial eye made of hard rubber, which very much resembles that which nature provides. It is needless to say, however, that, with a proper examination of the eye, as before explained, this fraud will deceive only those who are unobserving or inexperienced. But it is not the same with those which are blind in both eyes or suffer from amaurosis, in which the eye presents all its normal characteristics. These conditions can also be detected by a scrupulous inspection of the parts. The retina not being sensitive, the iris will remain stationary even when exposed to intense light, and when at liberty the animal will run against surrounding objects. Such horses are uncertain on their feet and not without danger as saddle-horses. Too much reli- ance cannot be placed on the word of the horse-dealer, and a thorough veterinary examination becomes a necessity to assure one's self of the integrity of the crystalline lens and the movements of the iris. A blind horse will supply, with the other senses, the deficiency created by the cessation of vision. The ears are extended forward, and, at the least noise, are directed forward and outward to perceive it. During progression, the elevation of the members is exaggerated, but their step is uncertain and the animal is predisposed to stumble. The carriage of 'the head is elevated to prevent falling, and the nos- trils are mobile, as if to examine the surroundings by the odors which they exhale. He carefully smells and feels with the orbicular tentacles all objects presented to him. The eyes are wide open, the mouth is sensitive to the slightest indication of the reins, and the ears are quick to recognize the voices of those who lead him or approach him. As Yallon l has written, he is susceptible of rendering good service if we understand how to use him and have the proper respect for him which his condition deserves. At work, as in the stable, it is neces- sary to place him alongside of one that is gentle and docile, because he cannot defend himself against the attacks of his neighbor. Worked in file, he should not be placed in the lead. We may add that when he is worked in harness he should always have the same driver, or the same rider when used under the saddle. In all cases his master 1 Vallon, Cours d'hippologie, t. ix., p. 318. 58 . THE EXTERIOR OF THE HORSE. should not forget that he must at the same time see for the horse as- well as for himself. E. The Cheek (Fig. 19). Situation; Limits; Divisions; Anatomical Base. The cheek is an almost plane surface, occupying the major portion of the lateral face of the head. It is limited in front by the temple, the eye, and the face ; behind by the branches of the inferior maxillary bone ; below by the commissures of the lips ; and, finally, altogether above by the parotid region. The cheek has an area more considerable externally than internally r where it forms the lateral parietes of the mouth. The latter surface i& generally, though incorrectly, not examined, and we will describe it in connection with the mouth in general. Its external surface is divisible into two regions: the one superior, the flat of the cheek, or the masseteric region ; the other inferior, or the buccal region. Their separation is indicated by a vertical gutter in front of the masseter muscle, in which are situated the glosso-facial artery and vein and the duct of Stenon. In its lower half these three structures lie side by side, the artery being anterior and the duct directly against the border of the muscle ; at its middle the duct passes obliquely forward over the side of the cheek, to penetrate it opposite to 1 the anterior border of the third superior molar tooth. Its base is formed by the masseter, buccinator, alveolo-labialis, zygomatico- labialis, and maxillo-labialis muscles, separated from the skin by the cuticularis colli. Their surface is covered by the sub-zygomatic plexus of nerves; the superior and inferior molar glands lie opposite to the corresponding teeth. The five principal blood-vessels can be located from the exterior : the glosso-facial artery along the anterior border of the masseter muscle ; the superior coronary on the side of the superior maxillary bone, about an inch and a half from its alveolar ridge, with which it is parallel ; the inferior coronary between the branch of the lower jaw and the maxillo-labialis muscle ; the transverse artery of the face parallel with the zygomatic crest ; and the external branch of the maxillo-muscularis parallel with the curvature of the angle of the lower jaw. Beauty. The principal beauty to be sought for in this region consists of its distinct delineation, characterized by the fineness of the skin and the hairs, and the absence of connective tissue rendering the blood-vessels, the nerves, and the muscles distinctly visible through their thickness. Such we find it in horses which belong to the finer races. When it is excessive, it renders the head too sharp. In common horses, on the contrary, the cheek is round in the flat portion and flabby and thick in the buccal portion. Defects. The most frequent defect of this region is called the granary, and is due to irregularities of the molar teeth. In this condition we remark on the exterior an elongated tumor, often lobu- LATERAL FACES OF THE HEAD. 59 lated, produced by the bulging of the cheek in consequence of the accumulation of aliment between the latter and the molar arcades. It is observed principally in old horses. Horse-merchants always take the precaution to cleanse the mouth of such horses with vinegar and water before they are presented for sale, in order to mask the fetid odor which it exhales. The employment of these manoeuvres, how- ever, is insufficient for those who examine carefully the condition of the teeth, on the one part, and pouch in the cheek on the external sur- face, on the other. The latter, on account of its continual distention, is not closely applied upon the molars, but remains flabby, pendulous, and presents longitudinal ridges. We can understand that this defect of itself does not depreciate much the value of the horse, but that its gravity depends upon the cause which produces it and the means which remedy it. Blemishes. The blemishes of the cheek are traces of setons, indicating that the animal has been treated for an affection of the eyes or of the nasal cavi- ties. A seton improperly applied to this region may produce paralysis of the cor- responding lips by injuring the branches of the sub-zygomatic plexus of nerves ; the former is then drawn to the side opposite to that of the paralysis. A salivary fistula, following an accidental opening of the duct of Stenon, may be found on the maxillary fissure or the side of the face. A transparent, limpid liquid escapes from the opening, perhaps in jets, when the food is masticated on that side. It is a serious accident, on account of its long continuation, the ineffi- ciency of its treatment, and the malnutrition which results from the loss of the saliva. F. The Nostrils (Fig. 19). Situation ; Limits ; Form ; Divisions. The nostrils are the external orifices of the nasal fossa?, and the only passage through which the air can enter the lungs in solipeds, which respire only through the mouth in ordinary conditions. Designated as right and left, and situated at the inferior extremity of the head on each side of the median line, they are limited, internally, by the " tip" of the nose ; below, by the superior lip ; and, externally, by the cheek and the face. The form of the orifice is auricular or crescent-shaped, extending from above to below, and slightly from without to within. They present two lips, wings, or alee, and two commissures. Anatomical Base. a. The internal ala or lip, flattened and thin at its free border, which is convex, is turned downward and outward, and is constituted centrally by the nasal cartilage, whose flat portion, with the one on the opposite side, forms the cartilaginous plate of the extremity of the nose. The latter, covered externally by the transversalis nasi muscle and the skin, and internally by soft skin and mucous membrane, is prolonged downward and outward through the inferior commissure, to terminate in the external ala. 60 THE EXTERIOR OF THE HORSE. b. The external wing or ala of the nostril is concave. Its inferior ex- tremity contains a hard and resisting body, which is the termination of the curved portion of the preceding cartilage. In the remainder of its extent it is soft and flexible, formed only by skin and muscles. The muscles are all dilators. In some mammiferous aquatic animals, as the hippopotamus and the seal, there are constrictors to prevent the entrance of water into the respiratory apparatus. In terrestrial animals, on the contrary, the closure is prevented by the rigidity of their fibro-cartilage. c. The commissures are formed by the junction of the ala3. The inferior is round, concave, and continuous posteriorly with the floor of the nasal fossa ; the superior is smaller, acute, and is continuous, with a dependency of the skin called the false nostril. The latter is a cul-de-sac formed by a reflection of skin on the inside of the nostril, whose bottom lies at the angle of the incisive and nasal bones. It exists only in the domesticated animals, as the horse, ass, and mule, and admits of the introduction of the finger. 1 Around the margins, as are all the natural openings, it is covered by soft, thin, and adherent skin, continuous with the nasal mucous membrane. It is covered by two kinds of hairs : the one short, fine, and numerous ; the other coarse, long, and scanty. The latter, very deeply implanted and provided at their bulb with a nerve-filament, are organs of tactile sensation to the animal analogous to the moustaches of carnivora. They are more or less abundant, according to the quality of the race. The habit of cutting them with the scissors, singeing, or extracting them entirely, with the view of giving lightness to the head, is to be reprimanded. Beauty. The absolute beauty of the nostril resides in its width and in its separation from the lips, because it is proportional to the capacity of the respiratory apparatus. In solipeds, buccal respira- tion is prevented by the development of the soft palate. All the air which enters the lungs must pass through the nostrils, whose amplitude should therefore be in relation with the former. It follows, then, a priori, that the greater these orifices are the greater will be the vol- ume of air which enters the lungs during inspiration ; that conse- quently the development of the lungs will always be correlative to the dimensions of the nostrils, and vice versa. There is no exception to this rule, and the reverse has never been observed in nature. Small nostrils are an absolute defect, and associate themselves with a chest that is narrow and but little spacious. Movements. The movements of the nostrils are almost imper- 1 On the floor of the nostril, anterior to the mucous membrane, is the orifice of the lachrymal canal. It is round, excavated, punched-out, and resembles a glanderous chancre, for which it must not be mistaken. In the mxile and in the ass it is situated on the superior commissure. It is usually single, but may be double or even triple. LATERAL FACES OF THE HEAD. 61 ceptible in normal conditions and at rest. They dilate slightly during inspiration and become relaxed again during expiration. It is not thus during exercise ; their movements are accelerated in proportion to the efforts executed. Other circumstances, as the age, the temperature, and the seasons of the year, modify their frequency and often their rhythm. The causes of irregular dilatations of the nostrils or of ex- cessive rapidity of their movements should be carefully determined. These are always symptomatic of pulmonary emphysema or of some other grave affection of the respiratory organs. The examination in this case will, therefore, include that of the lungs, the trachea, the larynx, and, if need be, that of the other organic apparatus, if the accel- eration be due to their diseased condition. Examination of the Interior of the Nostrils. The exam- ination of the interior of the nostrils is made as follows : Let us sup- pose the animal to be held by the bridle or simply by a halter whose strap is passed through the mouth. Taking, for example, the nostril on the right side (Fig. 24), the inferior lip is seized with the left hand and the bulb of the right thumb is placed under the internal wing in order to remove it from the external, which is separated by means of the index finger. With this simple manoeuvre it is usually suffi- cient to inspect the state of the mucous membrane over a large part of its area. If it do not suffice, an assistant will hold the head, and both hands are used ; the internal ala is seized by the right hand and the external by the left hand, the head being so held towards the light as to expose the largest surface of the nasal fossa. In some cases reflected light from a mirror may be utilized. It is necessary to recall certain normal anatomical dispositions : The skin which covers the alse of the nose, preserving its characteristics, is reflected into the nostrils to form a cul-de-sac known under the name of the false nostril, and becomes continuous with the pituitary mucous membrane. The hairs with which its free surface is provided are destined to arrest particles of dust held in suspension in the air, which are obnoxious to the respiratory organs, and which, when inhaled into the more sensitive portions of the apparatus, cause irritation. At the inferior part of the* nostril', on the floor and a little anterior to the point of continuity of the skin and the mucous membrane, is found the external orifice of the lachrymal duct, giving exit to the tears in their passage through excretory apparatus and offering such characteristics that it cannot be mistaken for a pathological alteration. It is ordinarily single, but may be double and even triple. Its form is round, its edges perpendicular, commonly called punched- out, and the liquid which exudes is limpid and transparent. A cartilaginous septum, the septum nasi, separates the nasal fossae into right and left. It is covered by the mucous membrane and is related to a lamina 62 THE EXTERIOR OF THE HORSE. of nbro-cartilage covered by mucous membrane, and extending from the superior turbinated bone to the deep face of the internal ala. In a physical examination this lamina must be unrolled, for it is often the seat of pathological alterations. FIG. 24. Examination of the nostril. State of the Mucous Membrane. The nasal mucous mem- brane, in a state of health and of rest, is of a rosy color. After a certain amount of exercise, it becomes bright red, more or less intense, according to the plethora of the subject. It is paler and more follic- ular upon the branch of the aforesaid lamina of cartilage. Let us only indicate here that in a pathological state it may be pale yellow, leaden as in glanders, infiltrated, and may present on its surface liberations, pustules, small red spots, petechia, chancres, decortications, cicatrices, tumors, etc. All these symptoms pertain to diverse diseases concern- LATERAL FACES OF THE HEAD. 63 ing which we cannot occupy ourselves in this book. Let us limit our- selves to saying that the most serious of all is farcy-glanders, which should be particularly observed, and in the diagnosis of which the minute examination of the maxillary lymphatic glands must not be neglected. It is not rare to meet wounds in the region of the nostrils, which are found mostly in stallions, and involve the mucous membrane and the cartilage. At other times we find finger-nail marks which have been made on the pituitary membrane during the examination by inexperienced persons or those unable to control the animal. Normal Liquid of the Nostril. We have seen above that the normal liquid of the nasal fossae is clear and transparent, from the fact that it results from the continual discharge of the tears. In certain horses, when the atmosphere is cold, and much more in those whose lungs are emphysematous, we find the presence of a flaky dis- charge which adheres to the hairs of the nostrils, and designates the latter, according to horsemen, as being frosted. In pathological phenomena the liquid receives the name of dis- charge, and assumes certain characters which depend upon particular diseases. It may be : 1st. Adherent or not to the alse of the nose. 2d. Thick, tenacious, or clotted. 3d. White, reddish, yellowish-green, sometimes streaked with blood. 4th. Inodorous, fetid, gangrenous, or from caries. 5th. Unilateral or bilateral. In all cases the examination of the nostrils should be completed by that of the lymphatic ganglia. Entrance and Exit of the Air. The expired air merits also to be taken into consideration. It is of little utility to appreciate its quantity, either by placing the hand in front of the nostril, or, when the atmosphere is cold, by considering the two cones of vapor which escape. It is more interesting to assure ourselves of the regularity and equality of the column of air at its exit from the orifices, for it may meet obstructions of a diverse nature in its passage, as polyps, tumors, deviations of the nasal septum, etc. Some authors report that certain tradesmen, to mask the discharge, have placed a sponge into the diseased cavity. This fraud is very easily discovered, and requires no further explanation. In a state of good health the expired air is inodorous ; the bad odor with which it is contaminated proves a dis- ease of the lungs, caries of the superior molars, and, finally, prolonged 64 THE EXTERIOR OF THE HORSE. stasis of pus in the guttural pouches or in the frontal and maxillary sinuses. If there is doubt as to the veritable cause of this odor, the animal is made to cough by compressing the larynx with the hand, and standing to one side of the animal to avoid being contaminated by the expectorated matter. He is also made to snort by touching the sides of the median septum of the nasal fossae, which will immediately provoke such an effort and render the discharge visible if there be any. It is important to add that the air should pass in and out without making any sound; if a sound is perceived, the animal is affected with roaring. Roaring is acute and chronic. The former is temporary, the second permanent. It is a defect which nullifies the contract of his sale in some Continental countries. (Law of August 2, Article 2, 1884.) Cysts of the false nostril, between the layers of the integument which are placed in apposition to form it, are observed in some horses. We have seen several examples, and never have we remarked the least interference with respiration. We have proof of paralysis of one or of both nostrils. In the latter case the animal will find it an impossibility to trot, from the fact that the parietes of these openings are collapsed upon themselves and offer an obstacle to the introduction of the air. 1 Expression of the Nostril. Let us remark that the nostril is one of the principal organs of expression of the physiognomy. According to its state of contraction, dilatation, flaccidity, or crispness, it manifests in a thousand ways the sensations which the animal expe- riences. , Now it is surprise, fear, anger ; now joy, pleasure, anxiety, and suffering. Persons who are experienced with horses will soon become familiar with the expression of the organs, which defies all de- scription from the multiple shades in which it is manifested. We will return to this again, a propos of the head in general. Blemishes. The blemishes of this region are situated upon the alse of the nostrils, the nasal fossae, the appendices of the turbinated bones, and result from bites or lacerations. These may be produced accidentally in draught-horses by the hook which is often placed at the extremity of the shaft, when the animal is tied to a ring surmounted by a hook, or when, in turning the head, the nostrils strike against any sharp object. 1 A. Goubaux, M6moire sur les paralysies locales (Recueil de medecine vtrinaire, ann6e 1848, p. 229). POSTERIOR FACE OF THE HEAD. 65 Formerly the nostrils were slit to diminish the sound of neighing. The practice is still exercised upon the ass in the Orient. 1 We have several times repeated this operation upon the horse without producing any modification of the sound. The procedure is therefore inadequate. To recapitulate : 1. The nostril should be large and clear. 2. The mucous membrane, rosy at rest, more or less red after exercise. 3. The liquid which it discharges, clear and transparent. 4. The air which is exhaled, inodorous. 5. Inspiration and expiration should be noiseless. CHAPTER III. POSTERIOR FACE OF THE HEAD. A. The Intermaxillary Space. Situation ; Limits ,' Anatomical Base. The intermaxillary space is a symmetrical and triangular-shaped cavity, situated at the posterior face of the head, comprised between the two branches of the inferior maxilla. It is limited above by the throat, below by the chin, and on each side by the borders of the maxillary bone. Its anatomical base is the body of the hyoid bone and the muscles which attach to it, the inferior face of the tongue, and the intermaxillary lymphatic glands ; on each side, about an inch from the internal alveolar ridge, and underneath the glands, is the sublingual artery. The skin is fine, covered with hairs ordinarily longer than those in other parts of the body ; the connective tissue is abundant. Beauties and Defects. The principal structures which offer themselves for consideration in this region are the lymphatic glands. These should be small and movable without adhering to the surround- ing tissue. It is observed that in all diseases of the nasal sinuses, the nasal fossae, and the mouth, these ganglia become voluminous, painful, more or less adherent, and approach the corresponding branch of the inferior maxillary bone. In glanders they are decidedly adherent to the latter and to the base of the tongue. It is not only the inspection of these organs which requires our 1 Vallon, Cours d'hippologie, t. i. p. 232. 66 THE EXTERIOR OF THE HORSE. consideration, but we shall also examine the plainness, the width, and the depth of this region. It is plain or clean when all the structures which enter into its composition are distinct and can be outlined with the fingers. When the connective tissue is abundant the contour of the parts is not dis- cernible and the whole region is full or thick. Such is its structure in lymphatic horses raised in low and moist districts. The depth is related to the cleanness and the absence of connective tissue. The width of the intermaxillary space denotes a corresponding separation of the branches of the maxilla and a large development of the respiratory apparatus, since the larynx is partly lodged in that space, and thus protected from the movements of flexion of the head upon the neck. It is erroneous to believe that in horses in which the head is arched, this region is narrow, and that these are therefore much more predisposed to roaring. Exclusive of the general form of the head, it is true that there are certain subjects in which the inter- maxillary space is wider than in others. Professor Dupuy, 1 in 1829, has taken measurements of sixteen horses of different types, and proved a maximum width of 0.119 m., and a minimum of 0.087 m. In two horses which were roarers, the measurements were 0.079 m. and 0.063 m. ; hence it was believed as conclusive that the narrow- ness in the latter was due to a defective development of the maxilla and an insufficient separation of its branches, causing compression of the larynx. We cannot dispute the figures of Dupuy, but they are very exceptional. The skin of the intermaxillary space in common races is furnished with long, stiff, coarse, and abundant hairs, which make the head appear heavy and voluminous. Some are in the habit of singeing or extracting them, so as to render the head smaller, to disguise the race. Diseases and Blemishes. The general disease known under the name of strangles is often followed by considerable inflammatory swelling of this region and the formation of enormous abscesses of the lymphatic ganglia, of which we have spoken above. When the latter do not have their normal characteristics, it is said that there is a gland in the region, or that the animal is glanded. Great importance must be attached to this tumor, for it may be a symptom of a more serious disease, glanders. 1 Dupuy, De la fluxion vulgairement appe!6e period ique on Recherches historiques, physio- logiques et thrapeutiques sur cette maladie, auxquelles on a ajout des considerations sur le cornage, la pousse et la section des nerfs pneumo-gastriques, 8vo, Paris, 1829, p. 114. POSTERIOR FACE OF THT&MEAD. ^ 67 As consequences of these alterations, we may find denudations, excoriations, and cicatrices resulting from the application of medicines or from operations, as incising an abscess with a view of causing the disappearance, of the swelling. Formerly excision of the gland was practised in horses over five years of age, in which the gland was enlarged. Vegece had already considered this operation useless, the gland being only a symptom and not the disease itself. Strange to say, it has again been revived in some modern publications. B. The Inferior Maxillary Region (Fig. 19). Situation ; Limits ; Anatomical Base. The inferior max- illary region is a double area, having for its base the rectilinear branches of the inferior maxillary bone. It is limited internally by the intermaxillary space, externally by the cheek, anteriorly by the chin, and posteriorly, more or less distinctly, by the parotid region. Its internal face presents the course of the glosso-facial artery and vein and the excretory duct of the parotid gland, Stenon's duct. These three structures pass around the maxillary fissure, where they can be easily distinguished through the skin and where the pulse is counted. On the inner side the duct is superficial and the artery deep. The two rami of this bone circumscribe a V-shaped space with the apex forward, which corresponds to the intermaxillary space, and whose width, as stated above, constitutes an absolute beauty. They are not of the same thickness at all periods of life, and some persons attach enough importance to this to judge of the age of the animal by their examination alone. In young animals the molar teeth are deeply implanted into their alveoli, and the maxillary bone, for this reason, is of much greater thickness. Conversely, as the teeth are pushed from their alveoli, whose sides will then approach each other, there is an absorption of bone, the maxilla becomes thinner and the posterior border acute. This phenomenon can be utilized in determining the age, the border becoming sharp when the animal is about thirteen years old. This, however, is not absolute, and too much importance should not be attached to it. Descriptive anatomy has shown numer- ous individual differences. Animals of a lymphatic temperament and with large skeletons have thick maxillary bones. This is very marked in Shetland ponies. In horses of a nervous or a nervo-sanguinary temperament they are thin and fine. It indicates nothing but a race characteristic, and does not influence the qualities of the animal. In animals belonging to the common races this region, like the 68 THE EXTERIOR OF THE HORSE. intermaxillary space, is covered with long and abundant hairs, which it is the custom to singe, cut, or extrac.t. This practice is called to make the jaw or the hairs of the jaws. Diseases and Blemishes. These are osseous tumors, the result of blows which the animal has received or of injuries which are inflicted by the extrem- ities of the shafts. Again, we may find enlargements of the bone sometimes accompanied by necrosis and fistulae emitting an extremely disagreeable odor. The latter lesions are caused by diseases of the inferior molar teeth. Finally, this region may be the seat of salivary fistulae upon the course of the excretory canal of the parotid gland, most frequently on a level with the point where the duct is inflected around the maxillary fissure. These diverse alterations have a great tendency to assume a chronic form, and are always followed by deformities quite persistent, which blemish the animals for a more or less long period. C. The Chin (Fig. 19). Situation; Limits; Anatomical Base. Symmetrical and situated in front of the intermaxillary space and the branches of the lower jaw, and behind the tuft of the chin, the chin, upon which rests the curb of the bit, corresponds almost to the point of union of the two branches of the maxillary bone. The symphysis is manifested externally by a slight crest, a gutter, or a simple convex surface. These diverse conditions, with difficulty appreciated from the exte- rior, have caused this region to be named round or sharp, two confor- mations upon which buyers also attach too much importance. The impression of a portion of the harness or of the curb upon the skin depends much less upon the anatomical disposition of the parts than the degree of natural sensibility of the subject. It is easy to moderate the action of the curb by protecting the latter with a leather cushion and by regulating the quantity of traction exercised on the reins ac- cording to the sensibility of the animal. Denudations and wounds are the ordinary consequences of immod- erate pressure sustained by the chin of very irritable horses, as from the curb, or other traumatisms. There are also blemishes of the chin, which are not without interest in that which concerns special utilizations of the animal. INFERIOR EXTREMITY OF THE HEAD. 69 CHAPTER IV. INFERIOR EXTREMITY OF THE HEAD. A. The Mouth (Fig. 25). Situation ; Divisions. The mouth is a complex region which occupies the inferior extremity of the head and represents the entrance into the digestive apparatus. It is elongated from before to behind, and comprised between the two jaws. We recognize in it the following parts, which we will first study : 1, the lips; 2, the teeth and the gums ; 3, the bars; 4, the lingual canal; 5, the tongue; 6, the palate. We will afterwards pass to the examination of the mouth in general. i. The Lips (Figs. 19, 25, and 26). Situation; Limits; Anatomical Base. The lips are two movable musculo-cutaneous curtains, placed at the entrance of the mouth, whose opening they limit. They are distinguished as superior or anterior and inferior, or pos- terior. Physiologically, they are organs necessary to the prehension of food, and they serve as auxiliaries in mastication. The inferior lip, in relation to the exterior, to a small degree supports the bit, whose impulses are, in a certain measure, first received by it. The superior lip, the more mobile, is limited above by the extremity of the nose ; on the sides by the cheek and the nostrils ; by its free border, finally, it is in contact with its congener. The inferior lip is limited behind by the chin and laterally by the cheeks. The lips present for study two faces, external and internal ; two commissures, right and left ; and two borders, free and adherent. Each is composed of three layers, an external or cutaneous, an internal or mucous, and a middle or muscu- lar, besides blood-vessels and nerves. The muscular layer is constituted by the orbicularis oris muscle and the muscles of the face which attach to it. The arte- ries are the superior and inferior coronary, passing through the centre of their substance. The external face of each lip is covered by fine and very adherent skin, provided with two kinds of hairs : the one consisting of long, stiff, and scattered hairs, called tentacles, and deeply embedded in the subcutaneous tissue and even in the muscles ; the other, very fine, short, and numerous, belonging to the ordinary hairs of the coat. The former are provided with a nerve terminal at the base of their papilla, which makes them delicate organs of tactile sensation for the animal. To a large degree these supersede the function of the hand in quadru- 70 THE EXTERIOR OF THE HORSE. mana. The external face offers on the median line of the superior lip a small gutter more or less distinct, and on each side an elevation more or less prominent. This gutter is the representative of the nasal gutter, very pronounced in man and some other animals. This lip is, besides, longer, larger, more movable, and more constricted at its base than the inferior. In the latter, on the contrary, the median gutter is absent, to be replaced by some semicircular folds on a hemispheri- FIG. 25. Interior of the mouth (after Bruneau). cal eminence, more or less developed, to which has been given the name of tuft of the chin, and whose base is the mento-labialis muscle. The internal face of each lip, concave in every sense, is covered by the buccal mucous membrane, smooth, shining, of a rosy color in good health, and sometimes marbled, due to a deposit of black pigment. This layer becomes reflected on the incisive and inferior maxillary bones, to become continuous with the gums, and lies in contact with the anterior face of the incisor teeth. It INFERIOR EXTREMITY OF THE HEAD. 71 contains large numbers of salivary glands in the thickness of the submucous tissue. The connective tissue which unites it to the adjacent parts is sufficiently loose to allow of an abundant serous effusion. The free border of each lip is thin and bevelled, lies in contact with its congener, and is the point of continuity between the skin and the mucous mem- brane. The adherent border is marked in the interior of the mouth by a gutter at the point of continuity of the mucous membrane with the gums. Externally, it is not delimitated from the adjacent parts, with which it becomes continuous. The commissures are the points where the two lips become continuous, slightly round and quite thick, they are perfectly closed in ordinary conditions. Their volume appears much larger in young than in old animals, because the direction of the incisor teeth, upon which their internal face rests, becomes more and more horizontal with the progress of age. Also, the head in old horses seems to be tapering at its inferior extremity. The lip, like the nostril, the eye, and the ear, is a most remark- able organ of expression. When it is curled up, relaxed, lowered, elevated, or inclined, we have so many variations which affect the whole physiognomy. When we study the expression of the horse under the influence of pain, fear, pleasure, or distress ; when we ob- serve his attitude as he attempts to snatch or bite somebody or one of his companions ; when we observe the lips in "certain diseases ; when we translate the language of the stallion as he scents the mare, or the animal as he passes through the death-agonies, then can we see how perfect the expression is and how it varies in each circumstance. It is well known, also, that the physical qualities are in direct relation with the faculty of expression of which the lip is capable. The horse which is of a sanguine temperament, with a nervous system that is well developed, energetic, and easily stimulated by external causes, presents a high development of this region. The common horse, on the contrary, has a lip which is thin, soft, flabby, immobile, and without expression. The skin which covers it is thick and the hairs long, coarse, and abundant. The lips should approximate themselves easily by their free border to keep the mouth constantly dosed, in order to avoid a continuous escape of saliva. Nevertheless, it is not always thus, from the fact that the animal is " reined up too high," or that one of the lips may be paralyzed. In the first instance, the mouth remains open from the fatigue of the muscles induced by the unnatural position of the head ; in the second, there is great difficulty in the prehension of food, the constant loss of saliva is deleterious, and the physiognomy loses all its 72 THE EXTERIOR OF THE HORSE. expression. If the paralysis be unilateral, one of the lips is drawn to one side by the muscles which still preserve their nervous influence. If it be bilateral, the affected lip becomes pendulous. It is this which we sometimes see in the inferior lip of old horses and much more rarely in the young. This state is more often associated with a profound debility of the organism and an atony of the muscular system in gen- eral, than as a veritable paralysis, or at least as a complete inertia of the organ. Nevertheless, the defect in question may be congenital. Del- phine, an old brood-mare in the stud of Pin, suffered from paralysis of the inferior lip, and all her progeny inherited the same infirmity ; yet she was possessed of great energy and good breeding, and was not inconvenienced in the least (Richard). 1 . Certain horses, whether in harness or under the saddle, at rest or during exercise, have a continual and convulsive movement of the inferior lip which is very ungraceful to the eye. In the language of horsemen, it is said that they beat the lip. Again, some horses continually attempt to seize the branches of the bit with the lower lip, a vicious habit capable of changing its good direction. It is remedied in several ways, either by the application of a leather lip-strap to the bridle, by bending the branches of the bit backward, or, finally, by shaking the reins lightly at each new attempt of the animal, to compel him to let go. The commissures of the lips, according as they are situated more or less high, designate the mouth as being well, too much, or not enough cleft. This does not constitute a serious defect, because the bridle can always be so adjusted as to prevent the bit from exerting excessive pressure against the first molar tooth or the angles of the mouth. Most authors since Bourgelat have contended that the inferior lip can prevent the pressure of the bit upon the bars by opposing too great a resistance or interposing itself between the two. The former then offers considerable resistance to the bit, and the animal becomes hard-mouthed. M.. Richard 2 has amply refuted this assertion in pointing out the feeble resistance which the orbicularis muscle is able to offer against the bit, and in demonstrating that hard mouths result ordinarily from the inexperience of the rider in using the reins or the inaptitude of the horse to execute certain movements. On the inferior lip there exists sometimes, on each side of the median line, a tuft of long curly hairs, which are called, from the 1 Richard (du Cantal), tude du c.heval, p. 81, 6e d. 2 Ibid. INFERIOR EXTREMITY OF THE HEAD. 73 analogy of their form and position, moustaches. This peculiarity is also more rarely observed on the superior lip. Diseases and Blemishes. Diverse diseases, which may ordinarily pre- vent the sale of the animal, are observed in the region of the lips. Besides paralysis, of which we have spoken, farcy ulcers are sometimes observed here over the course of the lymphatics. Ulcers of variola also affect this region, attack- ing young animals principally. These latter ulcers may be situated upon .the ex- ternal surface of the lips, along their free border, as well as in the interior of the buccal cavity, and around the alae of the nostrils. Their gravity is of little con- sequence, and with care and practice we are enabled to distinguish them easily from the preceding, which are characteristic and serious in the extreme. Besides these alterations, the lips are the seat of swellings which disfigure the parts be- cause they extend into the surrounding tissues. Such are O3dematous effusion due to anasarca, the prolonged ingestion of certain plants, as buckwheat, for example, or the accidental application of vesicants, as when the animal rubs a surface which has been blistered for a therapeutic purpose. The most common blemishes of the lips are excoriations and cicatrices, resulting from the application of the twitch. These are always an indication of a vicious habit of the animal, difficulty in shoeing, or of his having been subjected to a surgical operation requiring frequent dressings. It is not rare to meet with cuts or lacerations along their free border. These wounds suggest falls, and it is important to examine with care the condition of the extremity of the nose, the incisor teeth, the gums, and the limbs, to inform ourselves as to the cause which has produced them. In old horses it is quite common to see thickenings or lacerations of the one or the other commissure, occasioned by repeated and violent traction on the bit or by a bit which is too narrow and improperly adjusted. These render the com- plete closure of the mouth impossible, and may prove to become obstacles to the prehension of liquids. The pain which they cause may, for a certain time, inca- pacitate the animal for service. Let us say, in conclusion, that we often see in horses affected with immo- bility particles of hay or straw adhering to the commissures of the lips and remaining there without provoking the least movement of the jaws. It is then said that he smokes his pipe. 2. The Teeth and the Gums. The teeth are organs of osseous appearance, implanted in the alveoli of the maxillary and incisive bones. They assist in the pre- hension and mastication of the aliment, and are distinguished from their use as incisors, canines, and molars. The relation of the teeth to the determination of age is so important to recognize that we will devote to it a special chapter. (See Age.) We will content ourselves for the present by saying that their minute examination should be made at the same time as that of the mouth, and include their integrity, soundness, length, direction, and the regu- larity of their surface. The mucous membrane which surrounds the teeth and aids to fix 74 THE EXTERIOR OF THE HORSE. them into their alveoli is called the gums'. These offer little of interest. In young horses they are rosy, thick, and adherent, but as the animal grows older they become pale and retracted from the teeth. Alimen- tary matters may penetrate between their dental surface and the teeth, excite inflammation, and become the origin of periostitis or of caries of the bone. 3. The Bars (Figs. 25 and 26). Situation ; Limits ; Anatomical Base. The bars, occupying the inferior interdental space on each side, include that portion of the inferior maxilla between the canine and first molar teeth, and are covered simply by the mucous membrane. In the mare, in which the tushes are undeveloped, the bars are longer, and extend from the corner incisor tooth to the first molar. They support the canon of the bit, Most authors have pretended that the conformation of the bars is of great importance relative to the pain which the horse feels as a conse- quence of the pressure of the bit ; that if they be elevated or sharp, the pain is intense, and, on the contrary, feeble when they are round ; finally, that the form of the bit should be adapted to the one or the other of these dispositions. We repeat here what we have already said above as to the bars : with equal sensibility it is certain that on the sharp bars the pressure will be more intense, but the difference which we observe in the sensibility to the action of the bit resides not so much in the con- formation of the parts as in the natural sensibility and irritability themselves, all peculiarities of this region. As M. Sanson * has justly said : when sharp bars accompany a nervous and irritable temperament, it is to this alone that & false or spoiled mouth, as well as the faults of rearing or running away, must be attributed. Most horses whose mouths have been abused with the bit by inexperienced riders or drivers present round and depressed bars. When the mucous mem- brane is thickened and the sensibility is blunted, they are called calluses. The bars may be the seat of wounds sufficiently grave to prevent the use of the animal for a variable period of time. Due to forcible traction on the bridle, these may terminate in caries, fistula, and exfoli- ation of a part of the bone which forms their base, and leave a perma- nent deformity. To recapitulate, the fineness of the bars constitutes the principal beauty to be sought for in their examination. 1 A. Sanson, Nouveau Dictionnaire pratique de mdecine, de chirurgie et d'hygiene vt<*ri- naires, t. ii. art. " Bouche." INFERIOR EXTREMITY OF THE HEAD. 75 4. The Lingual Canal (Figs. 25 and 26). Situation ; Limits ; Anatomical Base. The lingual canal is generally described as the space comprised between the branches of the inferior maxilla, in which the tongue is situated. It is a kind of gutter the sides of which are covered by the mucous membrane of the mouth. Anteriorly, where its inferior wall is formed by the body of the aforesaid bone, it is single ; posteriorly, it divides into two branches comprised between the sides of the rami of the same bone and side of the fixed portion of the tongue. At the anterior extremity of these lateral divisions is the lingual crest formed by the superior border of the sublingual gland, covered by mucous membrane, and presenting a series of orifices of the excretory ducts, ducti Riviniani. Underneath the mucous membrane covering the lateral faces of the tongue is the duct of Wharton, the excretory canal of the maxillary salivary gland. It opens upon the superior face of the body of the maxilla on each side of the frasnum of the tongue by means of an enlargement called the barb or barbillon, whose function is the protection of the canal against the entrance of alimentary matters. Depth. The lingual canal, which we must examine in regard to its depth, should be proportional to the volume of the tongue. If the latter be not in relation with the capacity of the gutter which con- tains it, the result will be a vicious position of the bit ; in the one case the tongue will entirely support the action of the bit, whilst in the other the latter will rest exclusively upon the bars. We must say, to speak the truth, that nothing has been demonstrated to establish this opinion. The width of the canal is always in relation with the volume of the tongue, and, should it be otherwise, the bit will experience neither more nor less difficulty, as we shall show further on. We think, also, that there is neither beauty nor defect to be appre- ciated in this region. We may, however, observe an inflammation of the canal of Wharton from the introduction, through the barbs, of particles of forage proving very often to be pieces of brome-grass. This affection is noticed most frequently in old horses with irregular teeth, and nourished on old Burgundian hay, in which this grass is abundant. It is accompanied by intense congestion of the barb, and perhaps a discharge of pus from its orifice. It was formerly believed that the barbs could prevent the animal from drink- ing. It is surprising that this opinion was even shared by Bourgelat, who con- sidered these organs simply as excrescences of the mucous membrane. At present, many persons in the rural districts are imbued with this prejudice, and employ horsemen and empirics who practice its ablation. It is easily understood I 76 THE EXTERIOR OF THE HORSE. that this barbarous operation facilitates the penetration of foreign bodies into the salivary canal, the entrance to which is thus no longer protected. 5. The Tongue (Figs. 25 and 26). Situation; Limits; Anatomical Base. The tongue is an organ of prehension and mastication of the aliment, of gustation and deglutition, placed in the lingual canal, and which completely fills the mouth when the jaws are in apposition. It is related above to the hard palate ; in front, to the incisor teeth and the lips ; on each side, to the bars, the molar teeth, and the cheeks ; and behind, to the soft palate. The principal structures entering into its organization are five pairs of muscles. Anatomically, it is divided into two portions : anterior, or free, and posterior, or fixed. The free portion is spatula-shaped and flattened from above to below. A fold of mucous membrane of a triangular form is detached from the middle of its inferior face and attached to the body of the inferior maxillary bone. This is the frcenum, or ante- rior pillar of the tongue. It limits to a certain degree the movements of this organ. Its examination, which should be made at the same time as that of the teeth, is conducted as follows, supposing the operator to stand on the left side (Fig. 26) : The left hand seizes the inferior lip or is placed upon the anterior face of the nose to steady the head. The right hand seizes the tongue ; the middle and index fingers are intro- duced between the lips into the mouth on a level with the bars, and the organ is grasped. Being thus held between these two fingers above and the thumb and anntilaris below, it is withdrawn from the mouth and, with its adjacent parts, carefully inspected. To examine the base of the tongue, it is necessary to stand in front of the head and allow the light to shine into the buccal cavity. These manoeuvres must be practised with the greatest gentle- ness. Excessive traction will be painful to the animal and make him insubordinate ; it may also cause a rupture of the stylo-glossus muscle, which we have several times proved by dissection, 1 as well as the genio-glossus and the frsenum. On account of the pain which is produced, certain dealers, without doubt, do not hesitate to practise this barbarous act on horses suffering from immobility, to make them timid and cause them to " back." 1 A. Goubaux, De quelques pratiques barbares auxquelles on a recours pour examiner la bouche du cheval, pour determiner son age, pour le faire reculer, etc. (Journal de l'e"cole de Lyon, 1866, p. 335.) INFERIOR EXTREMITY OF THE HEAD 77 The movements are elevation, depression, extension, retraction, and lateral inclination. Each changes the form and volume of the organ ; it becomes wider, thicker, concave or convex, etc. FIG. 26. Examination of the mouth. The volume, in general, is proportional to the capacity of the buccal cavity. We have never observed, except in very old horses, that the thickness of this organ caused it to project beyond the bars, become the sole support of the shank of the bit, and lessen, for this reason, 78 THE EXTERIOR OF THE HORSE. the sensitiveness of the mouth. The differences of sensibility, which are quite common, proceed from another cause. We have already spoken of this a propos of the bars and the chin. In a normal state, the tongue should always be kept in the in- terior of the buccal cavity. It helps to support the bit and, in con- cert with the lips, it receives its first impression. Some horses have the bad habit of doubling the tongue within the mouth by recurving its free extremity above or underneath the bit. This can be readily detected by separating the lips from each other, and is remedied by tightening the curb-chain. The integrity and entireness of the tongue should never escape the attention of the veterinarian. When a horse, tied with the reins of the bridle, or with a strap passed through the mouth, becomes frightened, he will throw himself violently backward and support the weight of the body entirely by the mouth, the point of attach- ment. Then, if the means of attachment does not break, the tongue may be sufficiently compressed by the bit or the strap to be cut trans- versely. We know of an instance of this kind in which the free por- tion was completely separated and fell to the ground. This is always a grave accident. If the section be incomplete, mastication is slow and imperfect ; if it be complete, death may be the consequence, as it was in the instance mentioned above. A horse should, therefore, never be at- tached to the reins of the bridle or to a strap passed through the mouth. The tongue may become lacerated or cut ? more or less deeply, on its lateral borders from irregularities of the molar arcades, which are denticulated in old horses. These wounds are very painful and prevent the animal from masticating his food. The remedy is the dressing of the teeth. There are some horses whose tongue, during work or at rest, pro- trudes from the mouth and becomes pendulous; this is called lolling the tongue. 1 In other cases it is alternately protruded and retracted in a manner which simulates the movements of a serpent's tongue ; hence the appropriate designation, serpentine. Both of these conditions are ungraceful, deleterious from the con- stant loss of saliva which could be utilized in digestion, and finally the organ ceases to give the same point of support to the bit which it furnishes in ordinary circumstances. 1 1 have seen an instance in which this was temporarily prevented by the application of a rubber band to its free portion, the effect of which, however, was an almost complete section of the organ. (Harger.) INFERIOR EXTREMITY OF THE HEAD. 79 6. The Palate (Fig. 25). Situation ; Limits ; Anatomical Base. The palate, which forms the anterior or superior wall of the buccal cavity, has for its osseous base the superior maxillary, incisive, and palatine bones. These are separated from its mucous membrane by a thick layer of erectile tissue, most abundant anteriorly. It is limited in front by the superior incisors; laterally, by the superior molars and the superior interdental spaces ; behind, by the attachment of the soft palate. Only a portion of it is visible in the examination of the cavity of the mouth. Its surface is of a- rose color, sometimes pigmented in different portions of its area. It presents transverse arches, with the concavity behind disposed symmetrically on each side of the median line, and separated from one another by transverse furrows. With the exception of the width, which is most marked in the finer races, the palate has no appreciable beauty or defect. The thickness varies according to the age and the physiological conditions. The palate may become congested and inflamed, projecting beyond the table of the incisor teeth and thus preventing mastication. This state is vulgarly termed lampas. It, however, is not pathological, but physiological, due to the irritation of dentition. Huzard 1 the elder has long ago shown the uselessness and cruelty of the practice of removing the swelling of this region by excision with the knife or by cauterization with the actual cautery. These bar- barous procedures impede mastication and tend more to diminish than to increase the appetite, as is shown by the animal's willing but inef- fectual attempts. They are still performed at the present time by far- riers and empirics, who call it burning the lampas. Scarifications practised for the same reason are not without accidents. They are made posterior to the third bar of the palate and not less than an inch from the edge of the gums of the molar teeth, so as not to puncture the palatine artery. B. The Mouth in General. All the secondary regions which we have studied in the preceding chapter should be in harmony with, one another, so that, as a whole, they may fulfil their functions. The mouth, indeed, requires examina- tion not only from a physiological point of view, but from that of the exterior also, in that it is the organ in which is lodged the instrument to guide the animal, called the bit. 1 Bourgelat, Trait6 de la conformation exterieure du cheval, 5e ed., p.^81. (Note de Huzard pere.) 80 THE EXTERIOR OF THE HOUSE. The Bit. This instrument (Fig. 27) is composed of a cylindrical piece of metal, wood, or rubber, straight, curved, or broken, and two branches, to which the reins, bridle, and curb-chain are attached. The former, called the canon or bar of the bit, or the bitting, rests upon FIG. 27. Bit of bridle. the tongue and the bars ; the latter prevents deviation and increases the power. The bit plays the part of a lever of the second class, in which the curb A is the fulcrum or point of attachment, P the point of applica- tion of the power, and R the place where the resistance is overcome by pressure upon the bars. PA representing the power-arm of the lever, it will be at once perceived that the longer the branches of the bit the more powerful and energetic is its action. The latter augments, with the diminution of the arm of resistance, the distance from the canon to the attachment of the curb, AR ; also, if the bit be grooved instead of round, or if the free portion of the tongue be large and the pressure on the chin of increasing force, its effect will be more intense. INFERIOR EXTREMITY OF THE HEAD. 81 Functionally, the bit is, therefore, an apparatus of restraint which, by its pressure, more or less severe, on the bars and the chin, causes pain of variable intensity. Temperament of the Mouth. The animal will react in con- sequence of this pain, and Bourgelat designated the temperament of the mouth as the particular mode or intensity of this reaction ; in other words, as the special effect of the different sensations transmitted by the bit to the mouth. Thus, the mouth is qualified as being steady, true, or normal when it supports the bit with freedom, without uneasiness, pain, or fear ; when it neither struggles nor yields too easily to the action of the hand. The mouth is sensitive, tender, delicate, or easy when it perceives the most delicate impressions of the hand and responds to them with promptness. It is strong, hard, and thick when it yields only to energetic traction on the reins. A spoiled mouth is one which reacts falsely towards the indications of the bit, whatever may be its sensibility otherwise. Finally, the fresh mouth or the active mouth is that which relishes the bit, chews it without cessation, and appears slightly frothy from the continual agitation which the movements communicate to the saliva. These different qualities of the mouth can only be judged by the utilization of the animal, but they should not be neglected on that account. In a general way it is always necessary, in the selection of a horse, to seek the most complete information possible and not omit any tests, if such be necessary. Overweening vanity is too often the cause of the most singular mistakes. We cannot insist too much upon the importance of examining all parts of the mouth, and of cen- suring those individuals who confine themselves to an inspection of the teeth with a view to a knowledge of the age alone. Internal Pace of the Cheeks. We will now refer to the internal face of the cheeks, whose external conformation we have already studied. It does not constitute a particular region by itself, but it limits laterally the mouth external to the molar teeth, as the lips do in front of the incisor teeth. It merits, nevertheless, some consideration, because it presents the round tubercle at the termination of Stenon's duct, opposite to the anterior border of the third molar tooth. Wounds or lacerations of the mucous membrane, the result of dental spiculse from irregularities of the molars, often exist here, particularly in old horses. They may produce inability to masticate, 6 82 THE EXTERIOR OF THE HORSE. the remedy for which is apparent. The subjects presenting these lesions are poorly nourished, their mastication is incomplete, and fre- quently food accumulates between the. molar arcades and the internal face of the cheeks, producing a peculiar distention (granary) on the exterior, which we have previously described. Method of Action of the Bit. The bit should be considered as a check which arrests, as a power which masters, and, above all, as a means of communication between the horse and he who directs him. The physical impression which it causes varies from the slightest sensation to the most intense pain. If the intensity of its effect is not properly measured with the degree of sensibility and the intelligence of the subject, it produces effects opposite to those which are desired ; it provokes an energetic and often stubborn defence, in which the man is not always victorious, and which may not be without danger to his person. If, on the contrary, the mechanical effect of the bit be in proportion to the sensi- tiveness of the mouth, so as to be a simple indication for the horse to surmise what is required of him, and, if necessary, to teach him by the pain that he must obey a will superior to his own, then it becomes a means of education entirely rational and utilized in his dressing for various purposes. It becomes an intermediary agent between two in- telligences whose communication is thus possible. It translates ideas and information from the language of the master into that of his ser- vant ; and, little by little, the latter will comprehend this language, although it varies according to the purpose for which the animal is employed, as the saddle, light carriage, or heavy traction. It is im- portant that the dressing should begin early and under a patient, firm, able, and experienced master. The bitting is the name given to the method by which the bit is most conveniently adjusted to the mouth of the horse. CHAPTER V. POSTERIOR EXTREMITY OF THE HEAD. THE posterior extremity of the head comprises three regions, of which one, serving to unite the head with the neck, is double. They are : the poll or nape, the parotid region, and the throat. POSTERIOR EXTREMITY OF THE HEAD. 83 A. The Poll or Nape (Fig. 19). Situation; Limits; Anatomical Base. The poll or nape occupies the summit of the head. It is limited laterally by the ear and the parotid region, anteriorly by the forehead, posteriorly by the crest of the neck and the mane. This region, which corresponds anatomically to the occipito-atloid articulation, has for its base, on the median line, the funicular por- tion of the nuchal ligament, separated from the surface of the atlas by a synovial bursa ; on each side are eight pairs of muscles disposed in several layers. Over the side of the atlas, corresponding to the two foramina, at the base of its transverse process, are the two principal blood-vessels, the retrograde and occipi to-muscular arteries, separated from each other by a space of about two inches. The skin which covers it is ordinarily protected by the mane, which is usually cut to lodge the head-piece of the halter or bridle. Diseases and Blemishes. The veterinarian must thoroughly assure himself of the fineness and freedom from disease of this region ; for, on account of the movements and the disposition of the muscles into layers, filtration is favored, and all diseases in this location assume an unfavorable aspect. 1 Wounds of the poll result sometimes from a misfitting bridle or halter and from contusions, consequent on the animal's rearing and striking the poll against resisting bodies. The most common result of these is fistula with necrosis of the tendons, nuchal ligament, and even the bones. This is extremely serious and often fatal ; sometimes a cicatrix alone betrays the disease. A less serious disease is a synovitis and dilatation of the above-mentioned bursa. The swelling is usually bilateral. No one but the most ignorant would buy horses with such blem- ishes without observing them. We know of instances in which the hood was employed to cover the parts. An abnormal sensibility of the poll is always indicative of a previous or now-existing disease, which can be demonstrated by passing the hand over this region. B. The Parotid Region (Fig. 19). Situation; Limits; Anatomical Base. The parotid re- gion, like the gland which forms its base, derives its name from its proximity to the ear. It is limited above by the ear, below by the 1 A. Goubaux, Note sur quelques lesions de la region de la nuque, chez le cheval (Arch, veter., 1877, p. 137). 84 THE EXTERIOR OF THE HORSE. throat, behind by the neck, and in front by the temple and the cheek. The external face of the parotid gland is separated from the skin by the parotido-auricularis and cuticularis colli muscles; underneath, it lies against the pharynx, larynx, guttural pouches, blood-vessels, and nerves, and is traversed obliquely from below upward, and from with- out to within, by the jugular vein ; the superior extremity embraces the base of the ear, and the inferior is lodged in the angle of union of the jugular and glosso-facial veins. Beauties and Defects. These are purely conventional and vary according to taste. The region, to be beautiful, it is said, should be light and depressed in order that the movements of the head may be free and extensive ; if too much excavated relative to the surrounding parts, the movements will be too easy, the saddle-horse will be able to defend himself against his rider, and the head is mal-attached ; if too salient over the regions which confine it, the horse becomes difficult to guide and direct, the movements are neither free nor extended, and the head is again mal-attached. These arguments do not rest on any given physiological rationale. It suffices to recall the anatomical disposition of the articulations and the muscles to understand that these conformations are arbitrary and render the contradictory theories valueless. A moderate depres- sion of the parotid surface is simply agreeable to the eye in that it makes the head appear to be better attached, and, for this reason, deserves the preference accorded to it. Diseases and Blemishes. It is of more utility than the preceding to determine the presence or absence of diseases and blemishes. We observe here tumefactions due to melanotic tumors, to alterations in the gland itself, as parotiditis, to diseases of the structures which surround it, as the guttural pouches, or to lesions of the surrounding veins. Parotid abscesses are often compli- cated with salivary fistulse, which allow the escape of saliva and produce mal- nutrition. The hood is again called upon by unscrupulous dealers to hide these conditions. Let us also mention denudations, cicatrices, and traces of the cautery, as well as other blemishes which result from the employment of a means of treatment of diseases of the larynx, the gland, or the facial vein. In such cases it is neces- sary to determine whether or not the animal is a roarer or suffers from an oblit- eration of the jugular vein. (See Neck.} In conclusion, let us mention the barbarous usage which consisted in com- pression of the parotid region with a farrier's pincers in horses suffering from violent attacks of colic, the cause of which was attributed to pain and engorge- ment of the parotid glands. In similar circumstances it was also the custom to beat and open the glands to quiet the animal. This operation, dangerous as well as absurd, often terminated in gangrene and its inevitable consequence, the death of the patient. We have proof of such an example. HEAD IN GENERAL. 85 C. The Throat (Fig. 19). Situation; Limits; Anatomical Base. The throat occu- pies the bottom of the curvature of the head upon the neck, or the sine of the cervico-cephalic angle. It is limited behind by the inferior border of the neck, in front by the submaxillary space, and laterally by the parotid region. It is a single region, which corresponds to the inferior face of the larynx and the origin of the trachea, which are separated from the internal face of the skin by the muscles. It is bordered inferiorly and on each side by the two glosso-facial veins. Its absolute beauty consists in its large transverse diameter, because the larynx, whose diameter is related to that of the throat, belongs to the respiratory apparatus, the capacity of which should always be extensive. Its narrowness is, therefore, an absolute defect, because it signifies lungs of small capacity. In examining a horse, the larynx is generally compressed with the hand to determine the cough, the character of which has an important clinical aspect. All horses, however, are not equally sensitive to this manipulation. In certain animals it is necessary to employ both hands to obtain this result, and in others it is entirely impossible to excite a cough. The character of the cough indicates the condition of the respiratory organs. Provoking a cough sometimes causes the ejection of a discharge which has been fraudulently concealed. As soon as such is visible it is judicious to examine the nostrils and at the same time observe any movements of deglutition. In some rare cases of glanderous ulceration of the larynx and trachea, the expectorated matters are thrown into the mouth and immediately swallowed. Abadie, of Nantes, who has first called attention to this fact, advises in these cases the opening of the mouth of the animal and allowing the secretion to run out. The blemishes of the throat are depilations, excoriations, and cicatrices, indicating the use of revulsives employed in diseases of the larynx and pharynx. CHAPTER VI. HEAD IN GENERAL. WE have studied in the preceding chapters the different regions of the head, as to their situation, form, beauty, defects, diseases, and blemishes. In other words, we have employed a system of analysis in endeavoring to point out the physical and anatomical characters, the integrity, imperfections, and good qualities of each region in particular. 86 THE EXTERIOR OF THE HORSE. This study will not be complete without a glance at the different parts as a whole, purposely reserved for a special chapter. This syn- thetical study will enable us to perceive much more easily the harmo- nious relations which should exist among them ; it will furnish us also with an opportunity of examining the head, as to its length, volume, direction, general form, attachments to the neck, movements, and their influence upon the displacement of the centre of gravity, and, finally, the expression. A. Harmonious Relations of the Head. M. Richard * was the first to insist, with detail, upon the fact that the relation of construction of the different regions seems to be- much more intimate in the head than in any other portion of the body. It is, he says, not rare to see, for example, a very beautiful hock associated with a defective haunch, a good shoulder with a defective croup, withers well made with loins concave and badly attached, a narrow chest with limbs strong and well formed, etc. Inharmonious proportions are infinitely less common in the head. Thus, large nostrils, well-situated eyes, ears widely separated, and a large intermaxillary space coexist nearly always with a wide forehead ; whilst a narrow forehead implies, in most horses, large ears, placed high and approaching each other, eyes but partly open, small nostrils, and a narrow intermaxillary space. The fineness and mobility of the ears and of the eyelids, the amplitude of the nostrils, the thinness of the lips, the vivacity of the eyes, and the intelligent expression of the physiognomy, are beauties which ordinarily coexist. It follows, then, that a good or a bad conformation of one part naturally permits a good or a bad disposition of another. Beauty of the forehead is not associated with narrowness of the nose ; that of the nostrils with narrowness of the intermaxillary space ; the intelligent ex- pression of a beautiful eye with stupidity of the remainder of the face. In a general way, it is correct to say that the beauties and de- fects of the head correlate themselves in a manner almost absolute ; but we must remember that there are some subjects in which these relations are defective. Therefore, in selecting a horse, such a desir- able quality as a wide forehead should not of itself be regarded as conclusive of general excellence. If the harmony be in nature, it is often destroyed by man, who modifies the natural conditions of existence of the domestic animals. i A. Richard, Etude du cheval, 5e 6d., 1874, p. 127. HEAD IN GENERAL. 87 X propos of the proportions, we will again revert to this subject. For the present we will only indicate the harmonious relations of the head without ignoring the possible digressions or exceptions to this principle, which is really less absolute than M. Richard has been willing to admit. B. Length of the Head. Since the time of Bourgelat, all have been generally in accord as to the classic length of the head : that the height of the body measured from the withers to the ground, or the distance between the angle of the shoulder and the hip-joint, should be two and one-hal/ times the length of the head. If these distances were more than two and one- half times the vertical diameter of the head, it was too short; if the reverse was true, it was considered too long. When it has an appropriate length, it is carried with grace, responds easily to the action of the bit, and does not overburden the anterior members. A head too long is too heavy, displaces the centre of gravity forward, restrains the movements of the anterior extremities, bears heavily on the reins, and diminishes to such an extent the speed and usefulness of the animal. If too short, it becomes lighter, more movable, and favors rapidity of movement by the removal of the centre of gravity from the anterior limbs. These are reasons of so little value that an excess or a deficiency in length can be compensated by a short or a long neck. In the saddle-horse, the head should be short ; if too long, it displaces the centre of gravity forward, and throws too much weight on the fore limbs. In the draught-horse, however, this objection disappears and is rather favorable to traction. We have seen many excellent horses which, according to the measurements indicated by Bourgelat, had this region very long or very short. In such instances, the length of the head is to be considered as to its harmonious development with the other portions of the body, which vary with size and race, rather than by its influence upon the real qualities of the animal. C. Volume of the Head. The volume of the head is represented by different names, which also express its coexisting peculiarity of construction. It is called fine when the osseous processes, the muscles, and subcutaneous blood-vessels and nerves are well outlined. This is an index of a good constitution, and is a reliable sign of good breeding ; whereas, indistinctness of these 88 THE EXTERIOR OF THE HORSE. component parts and an abundance of connective tissue always denote a soft, lymphatic temperament and a common ancestry. The head is termed gross or coarse when it is defective from an excess of all its dimensions, owing its volume more particularly to the great development of its bony framework. The objections to this con- formation are the same as to that of the long head. It is admissible, however, with the same restrictions that we made when speaking of the length of the head. In the draught-horse it is not a defect, because his power depends, in a great measure, upon his weight, and not so much upon the rapidity and extent of his movements ; also because it tends to fix the anterior part of the body when the muscles contract. The head is designated fleshy or plain when, in addition to grossness, there is an almost complete effacement of the blood-vessels, nerves, and osseous and muscular protuberances in consequence of the thickness of the skin and subcutaneous tissue, as well as of the diminution of the bony processes themselves. It reveals a weak constitution, a lymphatic temperament, and all the predispositions to which the latter is heir. It is called senile or sharp when it appears emaciated from atrophy and absorption of the adipose tissue and of the muscles. The emi- nences of the bones, such as the maxillary spine, become quite con- spicuous, the supra-orbit is hollow, the eye is deeply embedded in its orbit, the cheek flat, the face depressed over the maxillary sinuses, and the skin seems attached to the bones. In a word, it presents all the characteristics of advanced age and exhaustion from extreme usage. It must not be confounded with the senile head proper, of which we will speak further on. D. Direction of the Head. The long axis of the head may assume three principal positions relative to the vertical line : the oblique, the horizontal and the vertical. The last two qualifications are not to be taken literally, but as express- ing an approximation to the vertical and horizontal positions. The head has a good as well as a natural direction when it ex- tends obliquely from above to below, from before to behind, and forms, with the ground surface, an angle of about 45 degrees. The horse is thereby enabled to distinguish perfectly objects placed before him ; he is enabled to avoid them, and is less likely to stumble and fall. It is also necessary to add that the bit has a suitable point of support upon the bars, since the insertion of the reins or the lines is more perpen- dicular to *the branches of the lower jaw, which represent the arm of a HEAD IN GENERAL. 89 lever. But then there are other reasons of a purely mechanical nature (Fig. 28). We represent by the lines AB and AC respectively the directions of the head and the neck. The former being very movable, admit- ting of extension and flexion, we represent the direction of the exten- sors and flexors by th'e dotted lines Ce and Cd, in order to show at what angles they are inserted upon their lever-arm, the head. It is to be remarked that when the obliquity of the head is carried to an angle of 45 degrees, the extensors and the flexors have an incidence approach- ing a perpendicular direction, which they will not have when the head has any other inclination. The animal respires more easily (the larynx being neither in a state of compression nor exaggerated ex- tension), responds more promptly to the bit, is more readily controlled, and executes with greater facility any movements of the head which may be demanded. When the head is carried horizontally, the centre of gravity is. elevated and displaced forward and the stability of the equilibrium is lessened. The larynx and trachea are placed in a straight line, fa^il- itating the entrance and exit of air. The body being then in a state of unstable equilibrium, the hind limbs, which are principally concerned in locomotion, can more easily displace the centre of gravity, the ftre limbs, in order to avoid falling forward, move more rapidly, and loco- motion is thereby increased. 1 This position is not maintained at rest, but only during exercise, and more especially in horses which are ewe-necked and in young saddle-horses at the beginning of their dressing, when they are not yet habituated to the action of the bit. This attitude is expressed by say- ing that the animal carries his head towards the scent. If there are some advantages in horses carrying their heads in this FIG. 28. 1 It is a well-known fact that in our fastest trotting-horses the height of the posterior extremities exceeds that of the withers. This excess is an additional aid to the displacement of the centre of gravity by the hind limbs, according to the principle enunciated, and hence favors-an increase of speed. An opposite conformation will diminish speed. (Harger.) 90 THE EXTERIOR OF THE HORSE. position relative to the increase of speed, of which we will speak later, there are at the same time some disadvantages. The horse can- not so easily recognize objects immediately about him ; he cannot appreciate as well the nature of the surface over which he travels, and is more likely to stumble and fall. The most serious defect which this direction entails is that the bit cannot act perpendicularly to the bars. All the traction exercised on the bit tends to retract the com- missures of the lips and carry it against the first molars. The teeth may now grasp the bit, the animal may become uncontrollable, and is then said to have taken the bit. It is to be remarked, from another point of view, that in the hori- zontal position of the head the extensors attach at an obtuse angle, an incidence unfavorable to contraction ; the attachment of the flexors, on the other hand, is at an acute angle, also a less favorable incidence (Fig. 29, A). FIG. 29. This carriage of the head, when habitual, is nearly always accom- panied by a concavity or reversing of the neck. In such cases, as Professor Lesbre 1 thinks, the articular relations between the atlas and the axis will assume the normal condition most appropriate for the execution of all the movements. These would be extremely limited in extension if the cervical axis did not curve itself. Anat- omy also explains that lateral inclination of the head in such an elevated attitude becomes almost impossible, because its production 1 Lesbre, Communication orale. HEAD IN GENERAL. 91 requires a mean position of contact of the articular surfaces. Finally, the reversing of the neck, which is the consequence, renders the inser- tion of the muscles, now approaching the perpendicular direction, less defective, and at the same time increases the power of the mechanical action of the nuchal ligament (Fig. 29, B). It is sometimes impossible to prevent the animal from holding the head in this position. The remedy consists in the use of ihe_martin- gale, a strap of leather of suitable length extending from the bit to- the girth of the saddle. This apparatus is frequently added to the harness simply as an ornament. In sadclle-horses this faulty direction can also be prevented by the use of a martingale with rings at its extremity, through which the reins pass, and which act as a pulley to keep the latter in their proper position, and thus prevent the elevation of the head. When the head is held in the vertical position the centre of gravity is carried backward and downward. The line of gravitation approaches the centre of the base of support, whence ensues a state of stable equilibrium, more difficulty in displacing the centre of gravity, and less quickness of movement. This position of the head is objec- tionable in driving-horses and in running-horses, whilst in draught- horses it is not. A vertical head is always accompanied by an arched or swan neek> the appearance of which is agreeable to the eye. Besides having the defect which we have indicated, the head is not in a good position for seeing distinctly objects beyond a certain distance. The field of vision does not extend far enough ahead to enable the animal to avoid obsta- cles which may be in his path. Also, like those which carry the head in extension, he is apt to stumble and fall, but for opposite reasons. In this direction of the head the incidence of the extensors is acute and that of the flexors obtuse (Fig. 30, A). Here again the neck is incurvated or arched to preserve the normal relation of the articular surfaces of the occipito-atloid articulation and render at the same time the insertion of the muscles more perpendicular to the arm of their lever (Fig. 30, B). This vertical direction is less objectionable in the saddle-horse than in any other. In horses which present it the steps are short and the flexion of the knees (knee-action) is more marked. They are more sensitive to the bit, and quite manageable if the conformation be not exaggerated. When excessive, however, it constitutes a serious defect, as when the head is oblique from above to below and from before to behind, and its inferior extremity approaches the sternum. The effect of the backward 92 THE EXTERIOR OF THE HORSE. displacement of the centre of gravity has here reached its highest FIG. 30. limit ; according to the usual expression, the horse arches his neck to his breastj cannot see the surrounding obsta- cles, and removes his head entirely from the control of the hand. In certain subjects the branches of the bit are said to touch the pectoral region. This has not yet been proved by our obser- vation. If it be true it can be remedied by limiting the excessive flexion of the head FIG. si. upon the neck by means of an over- check, a system of straps extending from the saddle to each side of the bit and inflected over the poll (Fig. 31). E. Forms of the Head. At the beginning of the chapter we compared the general form of the head to that of a quadrangular pyramid, in order to establish the HEAD IN GENERAL. 93 different subdivisions and facilitate their description. This compari- son is not sufficient to specify clearly certain conformations which must be described, and to which have been given particular names. 1 . The head is called straight when its anterior face is rectilinear in every sense. It is accompanied ordinarily by a wide forehead and nose, large nostrils, wide separation of the ears, the eyes, and of the branches of the lower jaw, exceeding fineness of the skin, of the eyelids, and of the lips, and a high faculty of expression. It is the type of absolute beauty ; it indicates the nobleness of the animal, his purity of blood, his energy, and his kindness of temperament. It is found in Aryan and thoroughbred horses and their descendants of mixed breed. It is the one most highly appreciated. 2. The conical head is that which is much contracted at its inferior extremity. It is regarded as a defect, because it presents, it is said, all the characters opposed to those of the preceding form. This is true in many cases, and some who designate the beauty of the head by saying that the horse should be able to drink from a glass, little suspect that they indicate precisely the defective point ; the animal is nearly always incapable of performing work requiring force and energy. Yet we have known, for several years, excellent horses which had the conical head. Old subjects, from senile atrophy of the max- illary bones and the change in the direction of the incisor teeth, some- times acquire this form of head. In a general examination it is necessary, therefore, to assure our- selves that the forehead and nose are wide, the jaws well separated ; in a word, that the head does not present one of the more exceptional forms of which we will speak immediately. In the latter the anterior surface of the head is characterized by a curvature more or less marked, which may be concave or convex. These have received special names. 3. The head is arched when the profile of its anterior face is convex. 4. It is called hare-faced when the convexity is limited to the region of the forehead. 5. It is designated ram's head when the convexity is limited to the nose. I)e Curnieu also described the hurdy-gurdy head, so named on account of its resemblance to the profile of that instrument. It pre- sents " a curve, more or less pronounced, extending without interruption from the poll to the lips ; it ordinarily has considerable expression and indicates a pure line of descent." It is not necessary to dwell upon this variety, as all its characteristics correspond to those of the arched form. 94 THE EXTERIOR OF THE HORSE. The convexity of the head, whatever may be its extent and degree, is not very desirable, on account of its inelegance and the habitual nar- rowness which accompanies it. For a long time, more especially during the last century, the con- vex head was very much in demand. But it was believed that horses which presented it had narrow nasal cavities and intermaxillary spaces ; that they were particularly predisposed to become roarers. By judi- cious crossing, attempts were made to cause its disappearance from the races in which it was most common, those of the north of Europe, Normandy, Limousin, Spain, Algeria, etc. To-day it is quite rare and is ceasing to be a distinct race peculiarity. Most authors have considered it as characteristic of a deficient development of the cranial cavity and the respiratory apparatus, and as indicating a predisposition to grave diseases. M. de Curnieu remarks that " it represents the ex- treme of degeneration ; the horse possessing such a shaped head is the idiot of the species, and is found in the poorest parts of England, Germany, and Normandy." 6. The head is snub-nosed when its anterior face is concave, or when the concavity is limited to the inferior part of the forehead. It is common among the Irish race, as the Irish cob and the Shetland pony, and in the Corsican and Sardinian ponies. Ordinarily short, wide, and in relation with the development of the respiratory apparatus, it is incorrect to believe that it is an objectionable characteristic. Nothing justifies this belief. It gives the animal a certain air of aggressiveness and independence ; it is often allied with marked robustness, great energy, and a series of other good qualities of the race in which it is observed. 7. The head is compared to that of the rhinoceros when the concavity exists only at the inferior extremity of the nasal bones. It was formerly observed in the Ardennaise horse and is a good conforma- tion, although perhaps disagreeable to the eye. It may be congenital or acquired : congenital, when it is present at birth ; acquired, when it is the result of pressure or of fracture of the nasal bones, as we have remarked in the chapter on the nose. It only becomes a defect in the latter case when, from displacement or the formation of a callus in the nasal fossae, it becomes an obstruction to respiration. The relative value of these diiferent forms is by no means absolute, and each one has numerous exceptions. We have known h arses with arched heads, which, during several years, performed extremely laborious services. In others, the width of the maxillary space by our measurements was as great as that in subjects with HEAD IN GENERAL. 95 straight heads. It appears to us very hazardous to believe that this conformation predisposes to roaring, and the facts which we will relate seem to prove that the observations made during the last century have been mal-interpreted. The lesions of chronic roaring do not reside in the nasal cavities. Among horses with straight heads roaring seems to be as common as among those in which they are convex ; finally, it should not occasion surprise to find roaring more common in some races than in others, this resulting not so much from an anatomical deTect as from a physiological weakness transmitted by heredity. This confor- mation is really only defective when accompanied by a veritable nar- rowness of the cranial cavity, the forehead, nose, nostrils, or maxillary space. In other cases it is perfectly reconcilable with services which exact force and vitality. The same argument is true as to glanders, to which horses with arched heads were, incorrectly, said to be more predisposed than others. F. Attachments of the Head. Attachments of the head is the name given to the mode of union between that part of the body and the neck. The head is said to be well attached when there exists a slight depression in front of the trans- verse apophysis of the atlas, extending from the poll to the throat. When its union with the neck forms a graceful curve, the movements are easy and extended. This is preferable in the saddle-horse and those used for light purposes. It is to be noticed in the finer races as well as in mixed breeds, in the English horse, the true Arabian, the Anglo-Norman, the Tarban horse, etc. The head is poorly attached, or unfastened, when the parotid grooves are too much accentuated. Often, with this arrangement, the neck is long and slender, the muscles of the members slightly developed, the loins depressed, the chest narrow, and the animal lacks strength and endurance. The head' is plastered on when the parotid groove is effaced. The subject is then heavy on the bit and appears unsightly. This condition is most objectionable in the saddle-horse. G. Movements of the Head. The movements of the head play an important part in the exe- cution of the different functions which it fulfils. It contains, first, the organs of smell, sight, hearing, and taste. We can add to these the sense of touch, although the latter belongs also to other regions. Whence it follows that the head is obliged to assume different attitudes in order 96 THE EXTERIOR +OF THE HORSE. to place the organs of which it is the seat in the best conditions to establish their proper relation with the external world. The most interesting movements for us to study, however, are those whose object is to modify the position of the centre of gravity while standing or walking. The head occupies, in fact, at the anterior part of the trunk, a position which also allows it to oscillate like a veritable pendulum at the extremity of the cervical stalk. It may be raised or lowered, remain in the axis of the body, or be displaced laterally, backward, or forward; in a word, the centre of gravity can be moved upward, downward, forward, backward, sideways, raised from the base of sup- port or drawn to it, removed from the centre of this base, forced out of it, or again drawn back. These multiple actions are produced still more freely by the head when it is attached to a long neck, in which case its movements are easier and more extended. Therefore, all the influence which it exercises upon locomotion can be understood, since, it can, according to the will of the animal, change rapidly the condi- tions of stability or instability of the equilibrium ; in a word, modify the speed. Not only do we speak of its extensive displacements, the effect of which is understood at first sight, but we also make allusion to its partial movements upon the neck. According to our researches, the centre of gravity of the head is situated on the median line, at the intersection of a transversal plane,' which passes posterior to the last superior molar tooth, and of a hori- zontal plane tangent to the palatine arch. Should the head be extended, it becomes a mass of about fifteen to sixteen kilogrammes, which will carry it, from this fact alone, in advance of the cervical lever, and which will tend to deviate the line of gravitation in front of the base of support. This is the attitude which it assumes in the race-horse when he is running at full speed. When it becomes flexed, reverse effects are produced ; when it is directed to the side, the corresponding anterior member will at once be overburdened, and the other as much disburdened. This is sufficient to explain the importance of these total and partial displacements. We will, besides, have occasion to return to the subject when describing, in their proper place, the gaits, the attitudes, and the movements which the animal performs. H. Expression of the Head. The face of the horse is certainly the part of the body upon which the sensations and the passions which he experiences show themselves HEAD IN GENERAL. 97 most clearly. When this faculty of expression is carried to a high degree, he is said to have figure and expression. The parts which are most particularly charged with the manifesta- tions of the different internal states of the animal are : the eyes and the eyelids, the ears, the nostrils, the lips, and the mouth. These organs, through the different attitudes which they take, depict, by turns, gentle- ness, vivacity, anger, sadness, depression, joy, pain, fear, frankness, courage, ferocity, aggression, savageness, indifference, stupidity, ennui, etc. Ordinarily, the faculty of expression of the head is in direct relation with the purity of the race, the quality of the animals, their energy, and their intelligence. But it is a gross error to believe that it is possible to appreciate the qualities of a horse from an examination of his physiognomy alone. The latter, like that of man, can deceive, perhaps still more, for it has not the same mobility and shades ; its language is less familiar to us ; its most powerful auxiliary (gesture) and its best interpreter (speech) is wanting. Besides, if the features of the face are quite well understood, through education and habitual inter- course, as regards horses of the same species, they become much less comprehensible when it is a question of different species having between them only limited relations. Man reads upon the face of his fellow-man sentiments which he feels ; long observation and habit are indispensable to him, on the con- trary, in order to understand the expressive manifestations of the horse. Besides, we should not be deceived about their value ; for in some select subjects in which the head clearly reveals the greater part of the internal passions, the mass of the body will often deprive it of expression. The ability of the buyer will consist, then, in the prudence with which he guards himself against the premature inferences that can be drawn from their absence. It must not be forgotten that he who exhibits the animal for sale is greatly interested in showing qualities which the horse' has not, or has only in a feeble degree, and can by a kind of special preparation the fear of blows, the blows received, the introduction of a piece of ginger into the anus, etc. give him an appearance of vivacity or energy which, unfortunately, will be only temporary. 98 THE EXTERIOR OF THE HORSE. PART II. THE BODY. CHAPTER I. SUPERIOR FACE OF THE BODY. A. The Neck. Situation ; Limits ; Anatomical Base. The neck is a sin- gle region, flattened from side to side, situated at the anterior extrem- ity of the trunk and supporting the head. Free on its lateral faces, it is limited in front and above by the pott, the parotid region, and the throat; behind and below by the withers, the shoulders, and the breast. It has for its osseous base a bony axis formed by the cervical ver- tebrae, sustained superiorly by the two portions of the nuchal ligament and enveloped completely by numerous and voluminous muscles. The trachea, the oesophagus, the arteries, the veins, the lymphatics, and, finally, the nerves leading to the head, occupy its inferior border. The mane adorns its superior border. This region is an important one to study, because it constitutes at the anterior part of the trunk the arm of a lever more or less long, whose extremity gives attachment to the head, which is a kind of resistance that follows all its displacements and concurs with it to modify the sit- uation of the centre of gravity during progressive movements. Divisions. Whatever may be the particular form of the region of the neck, it may be represented as a pyramid flattened from side to side, the base of which corresponds to its posterior and the summit to its anterior extremity. Its periphery presents, besides, two faces, a right and a left, and a superior and inferior border. 1. Lateral Faces. Each of the lateral faces is traversed over its entire length by a round thickening corresponding to the cervical ver- tebrae covered by the muscles, the most superficial of which is the mas- toido-humeralis. Above this enlargement is an irregularly-triangular SUPERIOR FACE OF THE BODY. 99 surface, on which are seen, in fine and well-bred horses, the digitations and directions of the muscles underneath the skin. Below, it presents a longitudinal depression along the side of the trachea, known under the name of jugular gutter. The width of the latter diminishes from before to behind ; its depth varies with the subject according to the form of the neck, the muscular development, etc. In those animals in which the neck is stag-like, or reversed, this gutter is more superficial. Whatever may be its disposition, it lodges under the skin a large super- ficial vein, the jugular, which becomes immediately very apparent when the circulation of the blood is interfered with by any obstacle, as the pressure of too small a collar, for example. 2. Borders. The inferior border is thick and rounded, because it has for its base the trachea. Its width from side to side is in rela- tion with the calibre of this conduit and the amplitude of the lungs. It constitutes, therefore, a mark of absolute beauty. The superior border, thinner than the preceding, supports the mane. Its thinness is a matter of beauty and is to be sought for ; but, in some old horses, especially stallions, it becomes invaded with adi- pose tissue, which renders it so heavy that it cannot sustain itself and falls to one side. Such a condition is called lop-neck, or fallen-neck, an ungraceful disfigurement which makes the application of the collar difficult, and is accompanied by deep transverse folds, which are always hard to cleanse, and in which colonies of acari often take refuge. We have seen some animals in which these furrows were sufficiently deep to bury the hand when the head was extended. The region of the neck should be examined as to its form, direction, or carriage, volume, length, mode of attachment to the head, and its movements. Form. The neck is called straight, or pyramidal, when its borders are rectilinear and its lateral faces nearly plane or but slightly rounded, according to the age, the sex, the volume of the muscles, etc., of the ani- mal. The head is then well supported and well directed. It is arched when its superior border describes a convexity more or less pronounced throughout its entire length. In this case the head is ordinarily carried in a vertical position and presents the defectiveness of which we have already spoken. If the convexity be limited to the anterior part it is designated swan-neck, by reason of analogy to the neck of that bird, whose graceful curvature it imitates. This form modifies, like the pre- ceding, the carriage of the head, but the vertical direction which the latter shows is less pronounced. Finally, the neck is reversed, or ewe-necked, when its superior border is concave, which implies a proportional con- 100 THE EXTERIOR OF THE HORSE. vexity of the inferior border. Many horses showing this conformation have, in front of the withers, a distinct depression. Most of them also hold the head in a horizontal direction, as we have indicated. In a general way, all these forms are so much more compatible with the velocity of the gait the more the head is carried in advance of the base of support and, consequently, as the cervical trunk is less convex along its superior border. The pyramidal and reversed forms remove the head farthest from the body and denote the greatest speed. On the contrary, the arched and the swan-neck, by their tendency to curve the vertebrae in the shape of an S, diminish the length of the neck, move the centre of gravity backward, and are more favor- able to its elevation and depression as well as to the lateral displace- ment of the trunk. They also offer advantages in the saddle-horse, in which grace, brilliancy, rapidity, and extent of movement are pre- ferred. These conformations can be acquired by means of mechanical con- trivances and appropriate dressing. All horsemen are in the habit of making the necks of their horses supple by obliging them to execute progressively the movements of extension, flexion, and lateral inclina- tion. The utility of such suppleness is easily understood, since this kind of functional gymnastics has no other purpose than to habituate the animal to use this balance so powerful and so useful with dex- terity and rapidity, and thus overcome the resistance of the head. We shall, farther on, see that these cervical gymnastics, carried to an ex- treme, will prove prejudicial in certain cases, while, when well employed, their efficacy becomes incontestable in certain others. Direction or Carriage. Independently of the particular forms which it assumes, the neck also carries itself in several directions relative to the vertical line. We shall consider three varieties : 1st. The vertical, or, more properly, an approximation to the vertical. In this attitude, which constitutes a point of beauty and indicates energy, the head is easily sustained, the animal is easy on the reins and the bit, and the movements of the shoulders are free and extensive (Fig. 32). Let mn and OJ5, for illustration, represent the directions of the shoulder and the neck respectively. The extensor muscles and the mastoido-humeralis will be schematically represented by the lines Bm and Bn. The latter, it will be plainly seen, has a more considerable length, and therefore a greater amplitude of contraction to elevate the scapulo-humeral angle and increase the arc described by the forefoot. We see, moreover, that the weight of the head, represented by the line SUPERIOR FACE OF THE BODY. 101 BR, indicating the direction of the force of gravity, is exerted at the end of the cervical lever at a very acute angle, an incidence which diminishes the intensity of the force of gravity. This explains why horses carrying the neck in this position are not hard-mouthed; the FIG. 32. head seems to weigh less at the end of the cervical stalk, in conse- quence of the slightly-perpendicular incidence of the line of gravita- tion. Finally, we call attention to the favorable insertion of the extensor muscles, Bm, which are in excellent condition to resist the weight of the head and to carry it backward in order to give freedom to the action of the anterior limbs. Horses with necks thus formed are well qualified for all the brilliant movements of tossing and balancing the head in the riding-school and in the parade. 2d. The Horizontal. We observe this direction in animals that are deficient in energy, in the common races, and in those which are 102 THE EXTERIOR OF THE HORSE. fatigued. " If the last," says H. Bouley, 1 " are prevented, by the resistance of the reins, from inclining the head towards the ground, they continually toss it up and down, and by this oscillating move- ment ease the muscles and relieve themselves of the fatigue which this position occasions." We also see horses that are attached to heavy loads assume this attitude occasionally, for reasons which we have seen when speaking of the direction of the head. Whatever may be the circumstances under which we observe it, the animal always has a hard mouth, and his gait is shortened. We must except, here, the race-horse, whose neck is held horizontally when he is urged to his utmost speed, but assumes another position under ordinary circumstances. All these facts are explained by the mechanical consid- erations employed above. Let, for example, mn and OC be the relative direction of the shoulder and the neck (Fig. 32). It is plain that the mastoido-hume- ralis is shortened, and therefore has a limited degree of contraction. Nevertheless, its insertion in the shoulder is much more perpendicular than in the preceding direction, whence it results that the muscle will be more powerful as regards the intensity of its action. We understand from this fact how it is that horses which become exhausted during a long journey carry the neck in this direction. Moreover, the line of gravitation, CR, of the head tends to become more and more per- pendicular with the cervical axis, which gives to the head a greater power of resistance and explains why these animals are always hard- mouthed. The head thus held displaces, besides, the centre of gravity forward, relieves the posterior extremity of the body from a portion of the weight sustained by it, and exacts a smaller expenditure of force in the propul- sive efforts of the hind limbs. 3d. Finally, the neck may assume an intermediate direction, that is to say, an obliquity of about 45 degrees. We see again, by inspecting Fig. 32, that in this instance the advantages and disadvantages of the two preceding directions are about equally distributed. The muscles have a mean length, and their incidence with the shoulder is favorable, the step is sufficiently extended, and the head is neither too light nor too heavy on the rein. In a word, for good service, this is the usual position assumed by most horses, the golden mean to which it should be reduced. Volume. The volume of the neck should not be too large. 1 H. Bouley, Dictionnaire pratique de mdecine, de chirurgie et d'hygiene veterinaires, t. vi. art. " Encolure." SUPERIOR FACE OF THE BODY. 103 It is important that the latter should be harmoniously proportioned to the other parts of the body, and only by practice are we enabled to judge of the characters which denote this harmony. Thus, it may be slender or thick, two conformations intimately associated with an excess or a de- ficiency of its length. However, in stallions the neck acquires a develop- ment which must not be considered as a defect. The effect of castra- tion is a diminution of the thickness of this region to a notable^ extent. Length. The length of the neck, which is measured from the middle of the anterior border of the shoulder to the anterior extremity of the transverse process of the atlas, is correlative to its volume, which should be neither excessive nor deficient, under penalty of destroying the usefulness of the animal. Let us see what happens when the cervical lever is lengthened or shortened on this or on that side of its normal dimensions. Let (Fig. 33) mn and OC be the relative directions of the shoulder and the neck ; FIG. 33. let, on the other hand, OC, OA, and OB represent the lengths of the neck gradually decreasing. 1st. When the length is proportional, OA, it allows a sufficient extension in the movements of the shoulder and in the displacement of the centre of gravity ; the head is not too heavy on the bit, and the cervical trunk possesses suppleness and a mean power of mobility. If to this quality be added a good direction and a high carriage, we will find the conditions most favorable for all general services. 104 THE EXTERIOR OF THE HORSE. The proper length of the neck cannot invariably be determined mathematically, as Bourgelat has pretended when he assigned to it the same length as that of the head. Although this relation may be con- stant, we find some compensations correcting the errors in the one sense or the other, and altering the external beauty no more than they influence the good qualities of the animal. We will return to this in discussing the proportions. 2d. When the neck is too long, 0(7, its greatest disadvantage lies in overburdening the anterior portion of the body and in bringing the centre of gravity too far forward. It frequently becomes defective, besides, by reason of its slender and emaciated appearance. Finally, it renders the head heavy because it increases the length of the lever of this resistance, CR. Nevertheless, nature often brings compensations which remedy the undue length of the neck and give to it the characteristics of a veritable beauty. This consists, first, in its elevated attitude, which does not permit of excessive weight on the anterior quarters, by displacing, to a proper degree, the centre of gravity backward. There is, in conse- quence, a firm, energetic, and powerful muscularity, which gives suffi- cient volume and counteracts the slender appearance. The smallness and lightness of the head diminishes the force of the resistance, jR, in its relation with the abnormal length of the cervical lever. This compensation, joined to a direction approaching the vertical, contributes to render the head lighter on the reins, because the line of gravitation in this case is applied at the extremity of the neck with an incidence more or less acute. It is useful to remark, also, that the length of the neck denotes a correlative development of the muscles, On, elevators of the scapulo- humeral angle, and therefore a large extent of contraction and a long swing to the forefoot. The insertion of the muscles on the shoulder being more perpendicular, their action will be for this reason more energetic. In addition, the neck, by lengthening itself, becomes more movable and acquires a greater influence upon the displacement of the centre of gravity. These are its real advantages in the race-horse, whose neck is not really beautiful unless it is long, very muscular, carried high, and provided with a light head. 3d. Finally, the neck may be too short, OB. In this case it presents advantages as well as disadvantages, according to the purposes for which the animal is intended. In driving- and saddle-horses, especially the latter, it lacks suppleness and mobility, is generally thick and massive, and renders the animal less subject to control. SUPERIOR FACE OF THE BODY. 105 It is essentially defective in the race-horse, because its movements are slow and have but a limited action on the displacements of the centre of gravity. Let us add that the pace lacks amplitude by reason of the defect in the length of the elevator muscles of the shoulder. Horses having short necks owe their speed less to the extent of the movements of the limbs than to their frequent repetition in a given time. It is not the same in the draught-horse, in which the work is effected altogether by his weight and the energy of his efforts. A short neck can be redeemed by a firm and powerful muscularity, which will furnish a large surface for the support of the collar and will, at the same time, indicate great power. The brevity of the cervical lever will be compensated again by its horizontal tendency, because the elevator muscles of the scapular angle profit by a more perpendicular insertion, without which the anterior displacement of the centre of gravity of the head would overburden too much the anterior members. In a word, the gait will be slow, whilst the energy of the effort will be carried to its maximum if, as we have said, the region has very vigor- ous muscles. From the preceding considerations, we must conclude that each kind of service demands a determined length of the neck : that for ex- treme speed we must have a neck of long dimensions, well carried, and supporting a light head ; that for great and powerful efforts we need weight and muscle, that is to say, a large quantity of contractile ele- ments and these in a voluminous mass ; finally, for ordinary speed and energy, the neck should have intermediate proportions. In all cases it must not be forgotten that between the medium and the extremes there is a whole scale of intermediate forms which are neither excessive nor deficient, and that when the neck attains either extreme there are still certain compensations for it perfectly compatible, if not with absolute beauty, at least with energy and vigor. Attachments. Those lines which mark the limits of the supe- rior and the inferior borders of the neck constitute what are called its attachments. A propos of the head, we have already spoken explicitly of the superior attachment. We know that there is a slight furrow on the external face of the parotid gland ; that the larynx and pharynx are easily lodged in the space between the rami of the inferior maxilla ; that the nape of the neck, the parotid gland, and the throat, as a whole, appear to present between the head and the neck a slight con- striction, whose rounded and graceful profile enables us to surmise_the 106 THE EXTERIOR OF THE HORSE. perfect freedom of their reciprocal movements. When these condi- tions are not fulfilled, the head is said to be plastered on, or mal- attached ; its movements are not so easy, as we observe it, more espe- cially in short and thick necks. " The inferior attachments of the neck/ 7 says H. Bouley (loc. cit.), " should be marked on each side by the slight relief which constitutes the anterior border of the shoulders; on each side of the trachea! border by the angle of union of the jugular gutters converging towards each other above the point of the sternum ; finally, towards the withers by a depression in front of the summit of this region, generally not well marked. In these conditions the neck has a good origin ; it is well (attached. In other words, it harmonizes with the anterior parts of the trunk, of which it is a continuation. The facts are not the same when the neck is meagre and thin, and its inferior border forms with the chest a very pronounced angle ; when the demarcation between it and the shoulders is established in an abrupt and salient manner ; when, finally, the depression in front of the withers is deeply marked. In such cases we say that the neck is mal- attached, or, better, that it is stuck into the thorax, a very striking expression, which conveys an exact idea of this defective confor- mation. 77 Since we are speaking of the inferior attachments of the neck, we will describe a peculiarity which is sometimes met with, and to which, for a long time, the name of cut of the spear has been given. " The cut of the spear," says Garsault, 1 " is a hollowness quite deep, which is seen in Turkish and Spanish horses at the junction of the neck and the shoulder, sometimes higher and sometimes lower. This is consid- ered as a very good mark, the cause of which is told in a fable, which says that an excellent Turkish stallion received a stab from a spear in that part, and that all his descendants he having been placed in the stud inherited this mark of honor." Lafosse, in his " Dictionnaire d'hippiatrique," observes with truth that this peculiarity is present as often on the left as on the right side, and that it is not hereditary. Special researches have demonstrated that it consists simply in a congenital atrophy of one of the dictations of the arigularis muscle of the scapula. The atrophied branch leaves a depression which extends to the level of its insertion on the corre- sponding transverse process of the cervical vertebra. Movements. Considered in its relation with the locomotory 1 Garsault, Le nouveau parfait marshal, 1770. SUPERIOR FACE OF THE BODY. 107 functions, the neck represents a balance which supports the head at its anterior extremity, and whose displacements carry it upward, down- ward, backward or forward, and to one side, at the will of the animal. Remarkably mobile, from the fact of the numerous pieces which form its osseous base and the powerful muscles which move them, this balance plays the greatest role in most of the attitudes taken by the animal machine in movement. We have already seen its influence upon the stability of the situa- tion of the centre of gravity. (See Experiments of Morris and Baucher, page 6.) This influence is still more apparent when the animal rises, lies down, kicks, prances, walks, trots, gallops, leaps over obsta- cles, etc. Under all these circumstances the neck is carried first to the side opposite to that part of the body which is to move first ; then it liberates successively all those parts which will continue this move- ment or terminate it. Its displacements are always proportional to those of the entire body ; very quickly depressed in kicking, elevated in prancing, moving from side to side in walking, and forward and backward in the gallop. When the movement has a certain degree of uniformity, and is accompanied with great speed in a straight line, the neck acquires then a relative fixity after being extended forward enough to induce the members to move with a celerity in accordance with the rapidity of the gait. We see this, for example, in the fast trot or the gallop. Some important practical deductions can be drawn from these facts, which may be employed in directing horses, as well as in equestrianism. If the rider desires the horse to move the left anterior foot when it is in repose, it is only necessary to make traction and urge him forward in such a manner as to increase the weight on the right fore member. If it be desirable to make him change the feet while he is gal- loping, it is only necessary to disburden this or that member by drawing the neck to the opposite side. If the animal be required to leap over an obstacle, the neck is raised to facilitate the half-prance which pre- cedes the leap. If, on the contrary, the object be to prevent him from falling on his knees, the head is forcibly raised in order to prevent the centre of gravity from being displaced outside of the base of support. It will be sufficient for us to point out a few instances, in order to demonstrate the importance of the cervical region in the various movements, so that we may be able to apply them intelligently in practice. Diseases and Blemishes. The blemishes of the neck are cicatrices, which have, according to their situation, different significations. We observe them 108 THE EXTERIOR OF THE HORSE. ordinarily on the lateral faces, along the course of the jugular gutter, and on the borders. On the lateral faces there are sometimes traces of setons, which occupy the superior third of its length. These are very significant, because they indicate that the animal has been treated for disease of the eyes, the nasal sinuses, or the encephalon, as vertigo. Along the course of the jugular vein there are traces of firing and linear cic- atrices, which suggest that the horse has been affected with inflammation of the jugular vein, or that he has undergone a serious operation in this region. It is important, then, to determine if one of these veins is not obliterated. To ascer- tain this it is sufficient to make pressure with the thumb over its course at the inferior part of the neck, in order to prevent the blood from descending towards the heart. The slight shake of the hand will reflect the waves of the column of blood to the upper extremity of the gutter when the vein is intact. The contrary effect will show that the vessel is obliterated and the circulation is re-established by collateral vessels. If the obliteration exists only in one of the jugulars, the inconvenience is not so great, because the circulation is still sufficiently active through the one of the opposite side. When, however, the obstruction exists on both sides, the animal is unfit to perform rapid service, because the collateral veins are insufficient for the afferent circulation, and congestion of the component parts of the head is the consequence. Moreover, the jugular vein being the vessel selected for phlebotomy, we are not able, under this circumstance, to have recourse to it in cases of emergency. Very frequently the bleedings, of which one of the veins has been the seat, leave their trace on the skin. A very small longitudinal cicatrix indicates the spot where the tissues have been involved by the fleam of the operator. At other times these traces are more apparent, manifesting themselves by varicose dilations, simple or multiple, along the course of the vein, at the level of the places where it had been punctured. This condition is called varicose. Along the inferior border we recognize cicatrices resulting from trache- otomy, that is to say, the artificial opening of the trachea for the prevention of asphyxia when the natural air-passages are occluded or have an inadequate calibre. It is necessary, in a case like this, to exercise the animal in every possible way to determine whether he is or is not a roarer. A horse that carries a tracheal tube permanently will almost completely lose his value,, and should not be purchased. We observe, also, along the inferior border of the neck, surfaces flattened from before to behind, arising from fractures of the cartilaginous rings of the trachea, or from a congenital deformity of the conduit, which infringe on its sides, and always diminish, in the same proportion, its internal calibre. Occa- sionally, difficulty of respiration arises in consequence of this affection, and we should fully satisfy ourselves as to the manner in which respiration is effected in horses with such a deformity. Finally, the superior border of the neck may present cicatrices following deep abscesses with necrosis of the nuchal ligament, a disease which requires a long time to recover from, and which should never be passed unobserved. These blemishes are ordinarily occasioned by the use of a collar too small or improperly fitted. From the same causes appear calluses and corns along the anterior border of the shoulder, or in the vicinity of the superior border of the neck. SUPERIOR FACE OF THE BODY. 109 The diseases of the neck are affections of the skin, as surfeit and mange along its superior border ; inflammation of the jugular veins, thrombi and phle- bitis ; lesions of the cesophagus and trachea ; inflammation of the lymphatic vessels, lymphangitis, followed by knotted indurations along the course of the vessels ; and, finally, lesions of the cervical ligament. We cannot enter into long details in this connection without going beyond our province. Suffice it to say, that most of these diseases continue a long time, and are difficult to eradicate, on account of the situation, the structure, and the movements of the region in which they are found. The Mane and the Forelock. Situation ; Limits. The mane and the forelock are formed by the horse-hairs which occupy the superior border of the neck and extend forward to the superior extremity of the head between the ears, and backward to the withers. a. The mane is to the neck of the horse, says H. Bouley (loc. dt.\ what the capital is to the column which it surmounts ; it beautifies the neck by concealing, under its undulating tufts, the angularity of the superior border, and thus gives to the latter a more graceful aspect. Its abundance varies according to the race, the sex, the age, the state of the genital organs, and the animal himself. In well-bred horses and in foals it is fine, silky, and not abundant, while it is coarse, long, and stiif in common horses and most plentiful in adults. Thus, it appears more bushy in the stallion than in the gelding or in the mare. This state of the mane and its color denote nothing absolute and have very little signification In this respect the indi- vidual differences are so numerous that all inferences as to the pecu- liarities of the animal's character thus deduced are uncertain as well as delusive. We habitually separate, with the scissors, the mane from the fore- lock at the level of the nape of the neck, where the head-stall of the bridle rests. The mane is said to be single when all the hairs which compose it fall on one side of the neck, regardless of their length. In saddle- horses it is turned towards the left side so that the rider may seize it in mounting the horse. In the case of draught-horses, which invari- ably occupy the same position relative to the pole, the one attached on the left side (near horse) has the mane on that side ; the one on the right side (off horse) carries it on the right side. This detail, how- ever, is often neglected. The mane is double when naturally parted in the middle, one-half falling to the right and the other half to the left side. Thus, being 110 THE EXTERIOR OF THE HORSE. exposed in the centre, it is soiled by particles of fodder and dust. It is difficult to preserve cleanliness, and the parts become the seat of such affections as herpes and psoriasis, which persist with so much tenacity that it is sometimes impossible to eradicate them completely. In their natural condition, as we have already mentioned, the hairs "fall from their own weight. They are in certain cases cut so as to assume an erect direction and form a sort of crest on the median line, outlining the convexity of the neck more distinctly and making the latter appear heavier. Such is the custom with ponies and small horses, and particularly those in which the neck is reversed, with the view of .rendering its appearance more agreeable to the eye. To-day this is the fashion even in the teams of the wealthy. Among the ancients it appears to have been the custom to cut the mane as a sign of mourning. To render it thicker and longer, the Arabs of Algeria, according to Vallon, 1 also employed this method for from one to four years, and sometimes even throughout the life of the animal. The hairs of the mane, like those of the tail, are ordinarily straight. One of our associates, Mercier, has communicated a remark on this subject, which was also believed by the Arabians : that it is in the white or gray horses with frizzled or curly hairs in which melanotic tumors are always found in the interior of the body, although none may have any apparent trace on the exterior, particularly under the tail and around the anus. This remark, the correctness of which we have verified a number of times, both on the living subject and in the cadaver, is very important because of the dangers to which animals affected with melanosis are predisposed. There are neither diseases nor blemishes of the mane. It is there- fore erroneous to attribute to this appendage what properly belongs to the superior border of the neck. b. The forelock is nothing more, properly speaking, than the superior extremity of the mane. It consists of a tuft of hairs varying in length with the animal and the race, which escapes between the ears in floating meshes, overshadowing the forehead and the eyes. Ordinarily, in the English thoroughbred horse it is light, fine, and silky. In the Arabian horse it is, on the contrary, long and heavy. In common horses it is long and coarse. Like the mane, it may be single or double. All proportions being preserved, it is most developed in Oriental horses. At the same time that it is an ornament to the 1 Vallon, Cours d'hippologie, tome i. p. 330. SUPERIOR FACE OF THE BODY. Ill head, it protects the eyes from insects and excess of light. It acts, perhaps, also as a protection to the organs contained within the cranial cavity against the solar rays, and in horses much exposed to the sun its removal is injudicious. The mane and the forelock sometimes attain extraordinary dimen- sions. We have seen well-bred and common horses in which the former descended to the level of the knees and the latter to the jnferior extremity of the nose. With certain exceptions, these appendages are not allowed to reach so great a length ; they are dressed by means of a comb or a brush. Sometimes it is desirable to render the mane, which was primitively double, single. This may be accomplished by removing a portion of the hairs by extracting them with the curry- comb and continually brushing those remaining to the same side, the right or the left, as may be desired, according to the fancy of the owner. If, instead of proceeding as we have just indicated, scissors were employed to remove the superabundant hairs, these would again grow and remain straight. We have known a horse which, in conse- quence of the want of skill of the person who had arranged the mane, had the latter falling to the right, while on the left the hairs were upright like a brush, giving them a very ungraceful appearance. B. The Withers. Situation ; Limits ; Anatomical Base. The withers com- prise a single region situated on the superior face of the trunk, behind the crest of the neck, in front of the back, and between the two shoulders. This region has for its anatomical base the five or six dorsal vertebrae which follow the first. Their summits, enlarged and tuberous, support a nucleus of permanent cartilage, to which are attached the corresponding portions of the nuchal and dorso-lumbar ligaments, very much widened. On each side are the cartilages of prolongation of the scapula, and the muscles to which it gives attachment. The spinous processes offer a large surface laterally for the attachment of the trapezius, the rhomboideus, the splenius, the great and small complexi, the small anterior serrated, the ilio-spinalis, and the transverse spinous muscles, arranged in so many superposed layers. The anatomical complexity and elevated situation of the withers afford an explanation of the gravity of wounds and diseases of this locality. The superposition of the muscles allows of easy filtration of pus into the surrounding parts. Beauties and Defects. The beauties of the withers reside in the/orm, elevation, extent, and freedom from blemishes thereof. 1 . Form. This qualification indicates that they should be well out- lined, and that the summit should be formed only by the tissues which 112 THE EXTERIOR OF THE HORSE. constitute their essential base. As H. Bouley l remarks, the superior border, under this definition, should alone present the inert parts, as the bones and ligaments. At the base, on the contrary, the thickness denotes a large development of the muscles which separate it from the internal face of the scapular cartilages. The abundance of the subcutaneous and interstitial connective tissue, the volume and non-compactness of the muscles, as well as the development of the muscular system in general, are the principal factors in the production of the lateral diameter of the region. Let us add, also, that it always has this aspect in an ordinary degree when its prominence over the surrounding parts (shoulder and back) is not very marked. Such withers are called coarse, thick, and low. They are found in horses with great assimilative powers, thick skin, stiff and coarse hairs, abundant connective tissue, voluminous and flabby mus- cles, lymphatic temperament, and strong and massive forms. On the other hand, an ordinary stature, a slender, fine, and distin- guished form, prominence of all the external anatomical eminences, a fine skin, an energetic nature, and dense and firm muscles always accompany well-defined withers. This form is the most desirable ; it indicates the race, the temperament, and, in a word, the distinction of origin, and all the qualities of the animal so characterized. When the latter peculiarity is extreme, the withers are called sharp. This conformation, which is often seen as a consequence of emaciation from old age or excessive labor, is an attribute of those animals which become very lean when subjected to severe work, and accompanies a general deficiency of muscular development. As Vallon 2 has remarked, it is particularly defective in cavalry horses, for it exacts the use of a very narrow and elevated arcade of the saddle in front, differing much from the ordinary model, and which is not always at our dis- posal in a campaign. Such animals are difficult and expensive to harness, give the rider an uncomfortable position, and are exposed to traumatisms of this region from the pressure of the saddle during a long march. They necessitate the continued observation of the veteri- narian and those who mount them. 2. Height and Extent. The examination of the height is not less interesting from the double relation of its utilization and its direction. Writers are not in accord as to the exact sense which should be attached to the word height when applied to the withers. In the 1 H. Bouley. Nouveau Dictionnaire pratique de medecine, de chirurgie et d'hygiene veteri- naires, t. viii. p. 72. 2 Vallon, Cours d'hippologie, t. i. p. 339. SUPERIOR FACE OF THE BODY. 113 first edition of this book we have wrongfully considered that the height of the withers should be viewed from their elevation in relation to the croup and the adjacent parts. In view of the criticism which this opinion has received, we recog- nize to-day that the relative height of the croup is not germane to the subject which we now have under consideration, but to the respective heights of the anterior and the posterior extremities of the body^ -^We will discuss this in the chapter on proportions, as to the dimensions of the body as a whole (see Height and length of the body ; Horses high and low in front). By the height of the withers should be meant, therefore, only the height of the eminence formed by this part of the body above the adjoining regions, such as the shoulders, the back, and the superior border of the neck. By extent we are to understand the total dimen- sions of the withers antero-posteriorly ; in a word, the degree in which it is prolonged towards the region of the back. This circumstance, de- pendent in a large measure upon the length and inclination of the spinous processes, necessarily enables the latter to play the part of the long arms of the levers of the extensor muscles of the vertebral col- umn, and is therefore a favorable condition for the development of speed. The height or elevation of the withers depends, on the contrary, upon several diverse causes, which we must determine. Among them we mention : a. The well-defined form, or the thickness, of which we have already spoken, which concur to modify the obliquity of the lateral faces in consequence of either the lowness or the prominence of the entire region, as the case may be. b. The length and obliquity of the shoulder, which tends to cover, to an extent more or less considerable, the sides of the apophyses of the first dorsal vertebra. c. The absolute length and vertical direction of these processes, which, by their summits, exceed to a variable extent the border of the scapular cartilages. d. Finally, the mode of suspension of the thorax between the anterior members, the effect of which is to produce a more or less marked pro- jection of the summits of the spinous processes above the superior border of the shoulders. The age, the sex, and the state of the genital organs have equally their influence. Poorly delineated in the foal and the young animal, the withers become more prominent towards the fifth, sixth, or seventh 114 THE EXTERIOR OF THE HORSE. year, the period when the bones have attained their full length and the body its complete development. In the mare it is less prominent than in the gelding or the stallion. In the latter, however, in which the anterior portion of the body is more extensively developed, it appears usually thick 9 muscular, low, and effaced. The relative influence of all these causes it is easy to comprehend. One may operate alone or several may be combined, and the height of this region should not be attributed exclusively to one alone, as the sole length of the spinous processes, for example, which hippotomists until the present time have asserted without oifering any proof to substantiate the claim. Taking cognizance of this relation, we have endeavored to prove, by numerous researches upon the living animal and the cadaver, that this opinion is well founded. It is true that we have frequently found an excess of the length of the spinous process of the fifth dorsal ver- tebra (the culminating point of the region) in horses with high withers, but we have also, all things being equal otherwise, none the less often seen this process only equal to and even shorter than the others. Moreover, we can affirm that this excess of length is not uncommonly met with in horses in which the region appears depressed. The spinous processes are, therefore, subject to great variations in animals not dissimilar in appearance 'These variations may attain five centimetres in the one case or the other. It becomes evident, then, that other influences, must assist in the determination of the prominence of the withers. They are those which we have enumerated above. Among them the most important, doubtless, is that which refers to the mode of suspension of the thorax between the anterior members. As to this assertion, our researches leave not the least doubt. We daily meet horses which have the same length of the ribs, the shoulder, and the spinous processes, the same inclination of these processes and the scapula, and the same state of muscular development, in which, nevertheless, the summit of the withers does not, to the same degree, project beyond the top of the shoulder. How can we explain this fact, unless it be due to differ- ences in the degree of the elevation of the trunk in its attachment to the anterior extremities? As a proof of this enunciation it has been ascertained, in similar instances, that the distance from the inferior surface of the thorax to the ground augments in direct ratio with the projection of the spinous processes above the scapular carti- lages. Let us remark, in passing, that in practice it is almost impossible to establish the relative role which is exercised by the one or the other SUPERIOR FACE OF' THE BODY. 115 of these causes to which the height of the withers owes its variations ; whether it be due to the length and vertical position of the apophyses or to the lowering of the thorax. But what is well demonstrated by experience is that the best type of withers in a horse is that which is as salient and as much prolonged backward as possible ; especially if the horse be expected to perform service at a rapid pace/ and also for work under the saddle. It is not very important to determine the real cause of the promi- nence of the withers* What is essential to know is that increased height in most instances means a lengthening of the arm of the lever of the spinal and cervical muscles and an increased freedom of move- ment of the anterior extremity of the body, two conditions, either of which favors the muscular contraction and movements of the anterior limbs, the rotation of the scapula, and, consequently, the movements of extension and flexion. These reasons suffice to justify the prefer- ence which is accorded to this conformation. It is well known that horses with loiv and thick withers have ordi- narily insufficient action and too much clumsiness of the movements of the fore limbs. The shoulder rotates but little, the animal is predis- posed to forging and interfering, and is unfit for service at a rapid gait. He supports the head insufficiently and is heavy on the bit. Apart from the foregoing objections, there is still another factor which aggravates this defect. This is the difficulty of maintaining the saddle in place, it having a constant tendency to slide forward and to make direct pressure on and bruise the tissues underneath. Hence result wounds and inflammatory affections, the effects of which are so often incurable. The use of the crupper is an insufficient preventive against such lesions, and may itself become a cause of pathological conditions, from its continued traction at the base of the tail. Let us close by saying that beauty of the withers not only involves the mechanical advantages which we have already considered, but it is also a sign of the noble qualities and the distinction of its possessor. It endows the surrounding regions with other important qualities, such as are indicated by the length of the shoulder and the height of the chest, and thus presents itself as one of the essential qualifications of this locality. Whenever the chest is deep, and the shoulders long and oblique, it is clearly recognized that the withers are elevated, well attached, and extended well backward, the general harmony presuming that, in most instances, the development of one of the elements of an 1 This is not invariable. Among our speediest trotters we find some in which the withers are high, and others in which they are low. (Harger.) 116 THE EXTERIOR OF THE HORSE. anatomical region coexists with that of the others, whatever may be their number. "With respect to the horse, however, it is necessary to guard ourselves against such an absolute generalization ; it is essential to remember that the shoulder or the thorax can give this region a prominence in which the withers do not really assume that importance which might be supposed from a point of view of the exterior. Such, at least, have been the deductions made from our own observations. Diseases and Blemishes. The withers, in consequence of their promi- nence, situation, and anatomical complexity, are exposed to numerous lesions of variable gravity. Blows, chafing, bruises, and bites are among the causes which may lead to swellings, wounds, or abscesses with profound complications of necrosis and caries of the bones, the muscles, and the ligaments. These affec- tions, known under the generic name of evils of the ivithers, render themselves apparent, in the majority of instances, by an extraordinary exaggeration of the sensibility, abnormal enlargement of the part, cicatrices, or fistulous tracts dis- charging pus, which leave their evidence by soiling and decorticating the adja- cent skin. Horses in such a condition are not rarely offered for sale, and we know of two instances in which the dealer cleverly concealed the tumefaction and the fistula, of which it was the seat, with a blanket. It is more common to meet animals which offer accidental white markings or cicatrices more or less large, where the skin is denuded, thin, and more easily excoriated by the contact of the harness. The presence of these cicatrices furnishes, besides, the evidence of a pre-existing disease implicating the muscles or the bones of the withers and the shoulder, which may result in some irregu- larity of the gait. They have an important bearing in an examination for soundness in the purchase of horses. Other blemishes may also result from the application of blisters or the actual cautery. They have their principal value, however, when the affection for the cure of which they have been applied has not yet disappeared. Such diseases are liable to return or become augmented under the persistent action of the causes which produced them. 3. The freedom from blemishes, in a general way, as related to the physiological appearance, is, therefore, as indispensable to our study as the form, the elevation, or the extent. C. The Back. Situation ; Limits ; Anatomical Base. This single region, situated on the superior part of the trunk, is limited anteriorly by the withers, posteriorly by the loins, and laterally by the ribs (sides). It has for its osseous base the eleven or twelve posterior dorsal vertebrae and* the superior extremity of the corresponding ribs. These bones give attachment to the different muscles which fill the costo-vertebral grooves, the great dorsal, the small anterior and posterior serrated, the ilio-spinalis, the transverse spinous, and the intercostals. SUPERIOR FACE OF THE BODY. 117 Its uses are of primary importance, because it receives the saddle and the weight of the rider. It transmits to the anterior part of the body the efforts of propulsion, which are communicated through the loins by the posterior limbs. The back therefore fulfils, by its con- formation, diverse requirements which we will describe. Direction. The back may present several directions. It is straight when it describes almost a horizontal line from before to behind. A straight back is a sign of great strength, for all the weight which the region supports is borne by the bones and tends to efface the rachidian arch. The saddle will, in this conformation, rest in a good position. The back is convex (or the animal is roach-backed) when it is slightly arched, prominent, and sharp near the region of the loins. Such a con- formation increases the conditions of solidity to external pressure, in which the preceding form is deficient, on account of this arch being exaggerated. It is incorrect to associate this condition with flat ribs and a narrow chest. Convexity increases the reactions of the back and shortens the gaits of the animal. The constituting vertebrae in this disposition are related in such a manner that all pressure made upon them from above to below is supported more by the bones than by the ligaments which unite them, whence less elasticity and flexibility in executing its various functions. The convex back, besides, is generally shorter than the other forms, and does not permit sufficient freedom to the extension and flexion of the posterior members in taking long and rapid steps. It is therefore a centra-indication of rapid locomotion. Horses in which it is observed are predisposed to forging; that is to say, the fore and hind feet touch each other when their speed is increased. The convex back, for these reasons, is a defect in saddle- and driv- ing-horses ; in those performing, on the contrary, slow and heavy work, it is of no consequence. When the dorsal region is concave from before to behind, the animal is designated as sway-backed or hollow-backed. This conforma- tion, congenital or acquired, is more faulty than the preceding, and any load borne upon it tends to efface the arch formed by the vertebrae of this region. Instead of the latter offering a resistance, from their mutual contact, to the weight which they support, such weight is almost entirely sustained by the ligaments. This fact makes the vertebral column become rectilinear or, when exaggerated, convex along its in- ferior border. The ligaments which maintain the dorsal arch normally are therefore submitted to constant traction during service, particularly if a weight be superadded to that of the viscera. We have often observed in old horses more or less voluminous exostoses disposed in a 118 THE EXTERIOR OF THE HORSE. series along the common inferior vertebral ligament. In our opinion r these should be attributed to the violent and continuous pressure of the saddle or the harness. If this be true, it is easily perceived that these excrescences on the body of the vertebrae are most common in animals which, instead of having this region straight, have it strongly concave. The first ill effect of this concavity is an overtaxing of the vertebral ligaments due to the displacement of the bones, a condition which com- municates to the rachidian column a greater flexibility than is physio- logical. The result is that the transmission of the impulsive action of the hind limbs communicated to the anterior part of the body is incom- plete. The region lacks sufficient rigidity, and a certain part of the force is wasted, to the detriment of the speed, since its effect is to deviate the vertebrae from their normal rectitude. Sway-backed horses are not adapted to work which exacts much force and resistance of the back. They cannot be employed as hunt- ers, runners, or cavalry horses, but should be reserved to draw vehi- cles, one with four wheels being preferred. With M. Bouley l we believe, nevertheless, that it is necessary to discriminate between a real concavity of this region and that which is only apparent, a condition sometimes existing in horses capable of the greatest exertion. The latter appears to be due to a concavity of the superficial surface of the back alone, to a peculiar curvature formed by the series of spinous processes, which may be shorter in the middle of this region than in front or behind. It is a veritable anatomical anomaly. In this case the arch of the vertebrae themselves is in a normal condition and fulfils all its functions. This remark should consequently be taken into account, and a positive judgment should not be expressed unless the proof is apparent. It has also been said of horses thus formed that the reaction of the back is less hard than that of the average horse, a fact which has recommended them to favor as saddle-horses. Some authors, a& Curnieu, Eugene Gayot, and Vallon, assert that this last fact is due to a different order of phenomena, which lead to a suppleness and ease of the movements. These result, in this view, not from any peculiar condition of one region alone, but from the conformation of the body as a whole. The latter interpretation is true, but it does not destroy the validity of the other. One isolated cause may produce the same effect as several others combined. 1 H. Bouley, Nouveau Dictionnaire pratique de mdecine, de chirurgie et d'hygiene veteri- naires, t. v. p. ISO. SUPERIOR FACE OF THE BODY. 119 We believe that the more flexible and elastic the vertebral column is the more it will disperse the effects of concussion from violent exertion or accidents. The back will at any time lose this quality as soon as the alternative efforts which elevate and depress it are enacted in an irregular manner. Let us recall the regular movements of the rope-dancer ; nothing more graceful and of better rhythm. But would they have the same rhythmical character if, for example, he attempted _ to jump without regularity upon his rope? Evidently not ! This comparison applies to a certain degree to our subject. In locomotion the weight of the body, whenever it touches its base of support, calls into activity the elasticity of the vertebral column, which describes oscillations whose amplitude is proportional to its elasticity, its degree of tension, and the energy of muscular contraction. If, for one reason or other, these oscillations are excessive, whenever the feet come into contact with the surface upon which the animal moves, an evident antagonism of forces Avill result, leading to a succession of rebounds, which render the reactions still more exaggerated, even more so than if the back had an opposite conformation. Here is, we think, the cause of the divergence of opinions 'which we have spoken of. Horses of this type frequently have very feeble reaction when their gait is rhythmical and perfectly regular, as in the ordinary trot or the gallop ; but the reactions become marked as soon as the oscillations of the vertebral column cease to be in accord with the movements of the foot in touching the ground, as in trotting or running at great speed. Sometimes the line of the back is oblique from above to below, and behind to before, instead of being horizontal, concave, or convex. Such a form is called dipped. This direction, due to a more or less marked elevation of the croup above the withers, entails an unequal distribution of the body-weight upon the four extremities. The centre of gravity is carried towards the fore limbs, increasing by so much the weight which they support. We shall hereafter have something further to add in respect to the objections which exist with regard to this type of struct- ure when we come to treat of the axial measurements of the body. Form. In horses whose muscular system is very highly developed, there exists on the median line of the back a longitudinal line or fur- row, which is slightly surmounted laterally by the environing parts on account of the volume of the muscles situated in the costo-vertebral gutters. This characteristic marks that kind of back which is called double. It is a peculiarity observed in heavy and well-muscled animals whose chest is wide, the back somewhat concave, and the withers low. Many subjects which present it at the time of purchase may not 120 THE EXTERIOR OF THE HORSE. retain it throughout their whole life. Under the influence of the work to which the animal has been submitted, and poor and innutri- tions alimentation, the double back often becomes single and the mus- cular organization in general loses its volume and its high degree of development. Conversely, the crest of the back becomes prominent and stands out in relief over the surrounding muscles in subjects emaciated from the ravages of age, or in those of a certain natural conformation whose chest is narrow, the back slightly convex, the withers high, and the muscles less voluminous. In the latter form the region is predisposed to become sharp, and is more exposed to wounds from the saddle or the harness. Length. The length of the back is in relation with the depth of the chest and the rapidity of the gait. Its measurement, which requires some judgment, is usually combined with that of the loins. The typical back is regarded as equal in length to the distance between the dorsal angle of the scapula and the external angle of the ilium or the haunch. The determination of how much of this distance belongs to the loins is of little practical utility, but it should be as small as possible. A long back implies a corresponding length of the thoracic cavity whose superior wall it forms. We know that it is indispensable to seek, for any kind of work, those anatomical dispositions which imply the de- velopment of the respiratory apparatus. Such development requires a proper separation of the anterior from the posterior members ; and this separation is in relation with rapidity of locomotion, in that it is the expression of the length of the muscles which pass from the trunk to the superior part of the limbs, as the psoas, great dorsal, and pectoral ; also of those which occupy the costo-vertebral gutters, whose function is the extension and propulsion of the vertebral column. Again, it en- larges the base of support and leaves a sufficiently large area underneath the trunk, circumscribed by the four feet, for the movements of the pos- terior limbs. The latter are thus less liable to come in contact with each other, and so to produce that disagreeable sound called forging. These advantages, however, are often diminished by the following associated imperfections, which the shortness of the loins cannot always rectify. The dorsal column being long, tends to alter its direction under the impetus received from the posterior extremities during the move- ments of progression. A certain part of this impulsive force is there- fore necessarily lost at the expense of propulsion. Further, from the augmented flexibility and diminished solidity of the vertebral column, SUPERIOR FACE OF THE BODY. 121 its depression, to an exaggerated degree, is rendered more easy, and the back may even become concave under the pressure of excessive weight. Long-backed horses are more predisposed than others to fracture of the vertebrae during surgical operations in the recumbent position. As to the short back, it presents the elements of great strength and solidity, transmits the action of the hind limbs with greater force, and rarely becomes sway-backed ; but, conversely, it lacks flexibility of movement, diminishes the capacity of the thoracic cavity, and limits the play of the posterior limbs. The animal is predisposed to forging as soon as he is obliged to lengthen his steps, unless the loins, by an excess of length, preserve the required proportions of the dorso-lumbar region as a whole. Under these circumstances this defect is apt to be obscured by one that is more grave, as we shall see further on. Most authors who have written of this subject pretend that short- ness of the back constitutes its first beauty. H. Bouley l has very judiciously asserted that this proposition is too absolute. A very short back is not desirable except in animals destined to carry heavy weights, as the shaft-horse, the pack-horse, the mule, the ass, and the saddle- horse. In the last, from which speed is exacted, a deficiency in the length of the chest should be compensated by the arching of the ribs and their increased projection backward. As to the diminished stride of the legs, it may be redeemed by the multiplicity and rapidity of their movements. An elevated carriage -of the head, throwing the weight upon the hind and liberating the fore limbs, tends to prevent forging. Moreover, by judicious handling, the short-backed saddle- horse can be taught, little by little, to elevate the anterior members quickly enough and sufficiently far in advance, so that they will not be touched by the posterior. The same considerations are applicable to animals other than saddle- horses, in which a long back would be deemed preferable, with the pre- sumption that the dorso-lumbar spine be well directed and strongly muscled. Width. The width is also one of the qualities of the back to be considered. It is in relation with the transverse diameter of the chest and the volume of the ilio-spinalis muscles. When the back is narroiv, the ribs are often flat, the thoracic cavity deficient in space or volume, the spinal crest too prominent, and the parts are predisposed to wounds and abrasions from the harness or the saddle. Thus narrow- ness of the back, for these reasons, may become a positive defect. 1 H. Bouley, loc. cit., art. " Dos." 122 THE EXTERIOR OF THE HORSE. Diseases and Blemishes. Various lesions resulting from a defective pattern or vicious application of the harness or the saddle are sometimes observed in this region. Such are denudations, excoriations, bruises, corns, cysts, abscesses, and fistulse which exist on the median line, or the lateral parts. Their gravity varies according to position and the anatomical structures of the parts involved. Cure is difficult in proportion to their closeness to the median line. Benign as they may appear at the beginning, there is always danger of complications which may prevent the animal from working for several months. The presence of cicatrices or of white hairs are the indelible evidences which follow lesions of this nature. Finally, we sometimes find the marks of blisters or of the actual cautery, which will indicate that the animal has been treated for some one of these diseases. D. The Loins. Situation ; Limits ; Anatomical Base. This symmetrical region, situ- ated behind the back and in front of the croup and the haunches, and limited on each side by the flank, has for its base the six lumbar vertebrae (sometimes only five), whose costiform processes continue posteriorly the costo-vertebral gutter. This gutter is covered by the transverse spinous and the ilio-spinalis muscles,, the anterior extremity of the gluteal muscle, and the aponeurosis of the great dorsal muscle. We will examine this region as to its length, width, form, direction^ and attachments. Width. The width of the loins is directly proportional to the development of the costiform apophyses of the lumbar vertebrae, and corresponds in some degree with that of the muscles named above. A wide loin is regarded as a feature of absolute beauty. Length. Whatever may be the work the animal is destined to perform, the loins should be as short as possible, a condition of solidity important to recognize, because the lumbar vertebrae have no support laterally, being simply articulated the one with the other. Its short- ness also favors the transmission of the impetus given by the posterior limbs, because it lessens the elasticity and mobility of the structures through which the force of impulsion must pass. As to the relation of the entire length of the dorso-lumbar region, the back should be long and the loins short, especially in saddle- and pack-horses. This point cannot be impressed too strongly. Form. As in the back, the form of the loins is dependent mainly upon that of the muscles. The median line is indicated by a crest or a gutter. In the former case, they are single, and should be well muscled ; in the latter, they are double. When the crest is very high, the loins are called sharp, which is a sign of weakness and feeble resistance. Direction. As to their direction, the loins are usually straight,. and their convexity is observed only in old horses, or in those abused SUPERIOR FACE OF THE BODY. 123 by excessive labor, in which the spinal column has been injured by the weight and muscular traction which the region has sustained. In gravely -diseased animals they are often arched and have lost suppleness. Attachments. The loins should become insensibly united to the croup and the back. When they are mal-attached, there exists in front of the former a depression of variable depth, which gives them such names as low, weak, false, and dipped. Besides, they are -often long, narrow, and feeble, peculiarities detracting from their strength. Examination. At all times, in conducting an examination of the horse, veterinarians are in the habit of pressing on the loins to determine by their flexibility the state of the health of the subject. This practice should be executed with some precautions. Taking a position at the side of the animal, with the back towards his head, the hand is passed downward over the back, and the loins are pinched on the median line by making gentle pressure with the thumb and index finger. Under this influence the animal, when in a state of health, will extend the spine, or flinch. In those suffering from weakness or certain few diseases of this region, as osteoporosis, or in those of a nervous temperament, the sensitiveness may be much exaggerated. In horses suffering from fever or some other diseases, the region will remain per- fectly rigid. In a general way, its sensitiveness affords an index of the health of the animal. Certain nervous subjects will resist this manipulation by biting or kicking ; in order to avoid this, the head should be raised and the position of the clinician should not be too close to the body. Others will yield to the first attempt, but resist a repetition by stiffening the parts. Diseases and Blemishes. The wounds of this region are of the same nature as those of the back. They result nearly always from a misfitting harness or its improper application. The posterior part of the saddle frequently bears on the origin of the loins and wounds them on the median line. These wounds are always painful and slow to cicatrize, and may prevent the animal from working for a long period. In olden times they were designated under the name evils of the loins. Strain of the loins, which is sometimes observed, is a much more grave affec- tion, but we will speak of it under the defects of the gait. It manifests itself as a great weakness of the posterior quarters, which is most apparent during locomotion, and renders its victim unfit for active service. The blemishes are traces of blisters or the firing-iron, more or less exten- sive, proving an old cauterization for a serious disease, principally strain of the loins. There may also be excoriations, white markings in horses of a dark color, or cicatrices of the same nature as those which we have indicated in the region of the back. E. The Croup. Situation ; Limits. The croup is a single region situated on the median line of the superior surface of the body. It is bounded in front by the loins, behind by the tail, and on each side by the thigh and the superior part of the buttock. 124 THE EXTERIOR OF THE HORSE. Although, from an anatomical and physiological point of view, the croup constitutes the first segment of the abdominal limb, yet, on account of its close relationship with the other parts of the back, we prefer to regard it, for our present purpose, as the terminal portion of the trunk giving attachment to the hind limbs. Solidly united with the vertebral column by bones and muscles, it helps to form the periphery of the pelvic cavity. Accordingly, we shall not, in this discussion, separate it from the other regions of the body with which it is so intimately associated. Anatomical Base. It has for its base the two coxse, HF (Fig. 34), firmly united on the median line, CD ; anteriorly they articulate with the borders of the sa- crum, S, and are immovable excepting for a certain amount of elasticity. These bones are covered by a large mass of muscles, some of which extend to the femur and to the tibia. On the side is the coxo-femoral articulation, 0, in which the head of the femur takes part, and which supports this region upon the posterior members. Considered from a point of view of animal mechanics, the coxa can be repre- sented (Fig. 35) by a bent lever, HOF, composed of two arms : the one anterior, HO, formed by the ilium, ex- tending from the external angle of the haunch, If, to the centre of the coxo-femoral articulation, ; the other, OF, formed by the ischium, extends from the centre of the hip-joint to the ischiatic tuberosity or the point of the buttock, F. These two bones form a a very obtuse angle, HOF, whose mean extent, as deter- mined by our researches, is from 140 to 145 degrees, but which may vary ten degrees in either direction, accord- ing to the individual. We will call it the ilio-ischlal angle. It rests by its summit, 0, upon the head of the femur, at an inclination varying ac- cording to the individual; sometimes it is inclined forward, and then the line of direction, HF, tends to be- come more horizontal ; sometimes it tends to an opposite inclination. FIG. 35. SUPERIOR FACE OF THE BODY. 125 Finally, the femur not always having the same obliquity, it forms with the ilium and the ischium two angles, HOC (ilio-femoral) and FOG (ischio-Jemorat). for this reason more or less closed or open. It will be perceived that the femur surmounts the centre of the articulation, 0, by the great trochanter, T. Among the groups of muscles we recognize 1st. The gluteal muscles, TH, TS, carrying the femur backward when their fixed point is H, or elevating the ilium when 7*is the fixed point. 2d. The flexors of the femur, HP, principally the psoas, RP, advancing the thigh when H is their fixed point, and depressing the ilium when P becomes the fixed insertion. 3d. The ischio-tibial (femoral biceps, semi-tendinosus and membranosus), FI and FF, extending the femur and flexing the tibia, have as their fixed point F or S; when / or /' is the fixed point, the ischium swings downward or upward. The remaining muscles are all similar in function to those already studied. We observe, therefore, that there are in this region two principal groups of muscles. The first, PH, flex the femur, carrying it forward ; the second, Tff, FI, FVj more voluminous, extend this region. When the femoral insertion is fixed these muscles are capable of producing the same movements of the croup. The flexors, HP, swing the coxae downward and forward ; the extensors rotate them backward. They can thus contribute directly or indirectly in supporting the dorso-lumbar region. The croup must be studied with regard to its length, width, thiekness, direction, muscular development, and particular forms. Length. The length is measured from the external angle of the ilium (haunch) to the ischiatic tuberosity (buttock). Bourgelat con- sidered it equal to the distance comprised between the summit of the head and the commissures of the lips. These dimensions appear to correspond in most horses of a regular conformation, except in thor- oughbreds, in which the croup is relatively longer on account of the exceptional smallness of the head. The length of the coxae is, without dispute, the most important con- dition of the beauty of the croup in animals adapted to any rapid ser- vice. Whilst it is not a necessity in draught-horses, it nevertheless adds to their usefulness and beauty. Among Arabians this quality is much appreciated. "As to the horse whose croup is as long as his back and loins united, you can safely choose him even with your eyes closed ; such a horse is a blessing I" This 'is one of their maxims. The principal idea which this metaphor teaches is that the long croup should always be preferred, to the exclusion of all others. The reason for this preference is readily perceived. The great development of its antero-posterior diameter corresponds relatively with the length of the muscles of the croup, notably those of the 126 THE EXTERIOR OF THE HORSE. gluteal region, the principal extensors of the femur. They, in con- nection with the other extensors of the hind limb, communicate to the body a greater impulse, which carries it forward by a sudden and forcible opening of all the locomotory angles and a straightening of the whole limb. The greater their length the more they will be capable of shortening during contraction, and, consequently, the greater will be the force which the hind limb possesses. This impulsion, besides, will have greater power, because the inser- tion of the muscles will have an incidence approaching the perpendicu- lar. The line CD', which represents the direction (Fig. 36), is less oblique to 5 (7 (or CO) than the line CD. Again, the length of the croup is concomitant with that of the ischio-tibial muscles, AB and A f B, which flex the tibia or rotate the coxae backward during rearing or progressive movements in which they FIG. 36. are concerned, as the gallop or leaping. Not only the length but the angle of incidence is also modified. This is not all. It is also instructive to inform ourselves as to how the length of the croup is produced, for there are three principal fac- tors which enter into its formation, 1st, the degree of openness of the ilio-ischial angle ; 2d, the length of the ilium ; and, 3d, the length of the ischium. The openness of the ilio-ischial angle, according as it is more or loss large, separates correspondingly the an rle of the haim -h from the SUPERIOR FACE OF THE BODY. 127 p}int of the buttock, and makes the croup long or short. This is illustrated in Fig. 37. The lines AB and A'E' are of unequal lengths, whilst they support angles whose sides are exactly equal ; nothing but the inclination of these lines has changed. It follows from this that if the increase of the length of the croup can exist without influence upon the real length of the ilium and ischium, it modifies, nevertheless, the direction of the region in such a way that 4^ tends to become, in general, more horizontal. We will return to this subject hereafter. It is curious to observe that in our larger quadrupeds the line of direction of the croup always passes perceptibly above the centre of the coxo-femoral articulation, whilst in our smaller species, as rodents and carnivora, for example, the ilium and the ischium standing more nearly in the same line, and making a less angle the one with the other, this line passes almost through the centre of the joint. The ilio-ischial angle, in this respect, seems more marked, or, if it be preferred, the angle is the more effaced as the volume of the body becomes less and the nimbleness of the movements greater. Thus it augments in size grad- ually from the horse and the ox to the pig ; from the pig to the smaller ruminants ; and, finally, from the latter to the carnivora and the rodents. This relative openness, or largeness of the angle, with the corresponding modifications in the length of the muscles, and of their incidence with the osseous levers, and the play of the angles of locomotion in the pos- terior extremity, seems specially adapted to the execution of the gallop and leaping. Whatever may be the interpretation, it is well known that in horses of great speed this angle is more open than in draught-horses. In animals used for rapid services, this conformation has the preference. It is manifested externally by the relation of the centre of the articu- lation with the line of direction of the croup. The length of the croup, however, is due, more than to aught else, to that of the ilium and the ischium, the ilio-ischial angle remaining the same. These offer some important individual differences. Thus we have seen the relation of these two bones vary from 1.55 to 1.87. iscmutn 1 The ratio augments in fast-trotting horses, and diminishes in hunters, saddle-horses, and draught-horses. The length of the ilium determines that of the muscles attaching to it, and favors the amplitude of the femoral extension, whilst that of the ischium fixes the vertebral column when the flexors act, and facilitates the rotation of the pelvis downward and backward. 128 THE EXTERIOR OF THE HORSE. Here are some very suggestive figures which show these dimensions relatively in certain species other than the horse : We have found the relation to be 0.57 in the swan; 0.87 in the turkey; 1.22 in the hare and the rabbit; 1.30 in the lion ; 1.50 in the cat ; 1.60 in the greyhound ; 1.56 in the goat. In the ox it is only 1.24 : it is smaller than in the horse. In all animals in which the anterior part of the body has no direct support, as in birds, or is comparatively heavy, as in the larger rumi- nants, or, again, when the natural mode of progression is galloping or leaping, the ratio diminishes in consequence of the relative increase of the ischjum. The result is- apparent. It is easy to determine the proportions of the two levers constituting the coxa, by the distance comprised between the centre of the articulation and the point of the buttock. This factor is at least useful, if not indispensable, in estimating the locomotory apti- tude of the animal. To recapitulate : the length of the croup is in close relation with the production of speed. The ilio-ischial line is an insufficient indica- tion, and often the source of error. We should primarily strive to estimate the length of the bones which constitute that line, and should attach only a secondary importance to the line of direction ; or, in other words, to the openness of the angle which they form. Thickness. Authors have said but little upon the thickness of the croup, a point which should, nevertheless, be taken into con- sideration. We may define it as the distance comprised between the antero-posterior axis of the coxae and the summit of the sacral spine. The interval between the sacrum and the coxae is greater at the outlet than at the inlet of the pelvic cavity, on account of the inclina- tion of the axis of the croup and the horizontal tendency of the axis of the sacrum. It varies singularly in different subjects, owing to the peculiarities of the form of the sacral spine and the general direction of the sacrum itself. This bone may often be curved in draught-horses, while it is ordinarily more or less rectilinear in animals possessed of speed, notably the English thoroughbred and his descendants. The more it is depressed the smaller will be the coxo-sacral interval, or the less the thickness of the croup. When it is straight, on the contrary, this interval augments, and the line which marks the profile of the croup contrasts more strongly \vith the ilio-ischial line. The region then appears horizontal. Numerous muscles, among them the ischio-tibial muscles, charged with the rotation of the pelvis and the fixation of the spinal column, attach to the sides of the sacral spine. Its straightness, also indicating SUPERIOR FACE OF THE BODY. 129 the thickness "of the croup, is, therefore, in relation with the length of the muscles, the extent of rotation of the coxae, and, consequently, the aptitude for galloping and leaping. This straightness may at the same time be considered, in horses of rapid movement, as an index of great power and strength in the upper part of the hind quarter. Width. The width is the distance between the external angles of the ilia, but depends also upon the separation of the points-of the buttock. In the skeleton, the interval between the external angles of the ilia always slightly exceeds the length of the ilio-ischial line ; in other words, the pelvis is wider than long, the excess varying from two to seven centimetres, according to our measurements. In the living animal it is otherwise on account of the thickness of the muscles which cover the ischiatic tuberosity ; the length of the croup becomes equal to, and sometimes exceeds, its width in heavy horses from two to five centimetres. The development of the transverse diameter of the region varies evidently with the race and the conformation of the animal, but is, in general, an index of the volume of the muscles, and, consequently, of their contractile power, the fibres or contractile units being more numerous in a wide croup than in any other. Such a croup is, there- fore, an absolute beauty, and a most desirable feature in a horse, no matter for what service he is intended ; but it is especially desirable in horses used for heavy work, in which the greatest possible effort is exacted. It is even more desirable in broodmares. The separation of the haunches is far from furnishing, though it be so regarded, the best criterion for judging of the true width of the croup. Horses having an equal measurement over the haunches may have, in reality, ilia very different in their transverse diameter. It is not rare to meet some subjects whose haunches are less separated than most others, but whose pelvic measurements and iliac surfaces are con- siderably larger. We have convinced ourselves that these individual differences depend upon the following causes : 1st. The degree of inclination of the iliac surfaces from above to below. 2d. The degree of concavity of the external iliac fossae. The first cause effects a lowering of the external angle of the ilium in relation with the summit of the croup, and brings it towards the median plane of the body, a circumstance which, it is true, diminishes the distance between the haunches, but which exercises no influence in any manner upon the peripheral surface of the bone for muscular attach- 9 130 THE EXTERIOR OF THE HORSE. ment. An apparent narrowness of the croup, due to this cause, may exist, all things being otherwise normal, so marked as to diminish the transverse diameter of the croup by more than six centimetres. As to the degree of concavity of the external face of the ilium, its influence is easily understood. It augments thereby the surface des- tined for muscular insertion. Let us confine ourselves by saying that it is often much more pronounced than can be determined from the exterior. The practical conclusion to be drawn from these statements is simple : to judge well the width of the croup, it will suffice to consider the transverse dimension of the cavity of the pelvis. With equal length of the ilium, preference is to be given to the horse in which the sides of this region are inclined, that is to say, a great difference of level between the haunch and the summit of the croup is desirable, the separation of the haunches remaining the same. Two objectionable consequences may result from excessive width of the croup and a too marked inclination of its sides. Too widely separated from the median line, the coxo-femoral articulations require too large a base of support, and consequently produce exaggerated lateral oscillations of the posterior part of the body during locomotion. From this results an ungraceful swaying of the buttocks, which has been called the rocking of the horse ; whence results a loss of force and time proportional to the extent of these movements and the excessive oscil- lations of the centre of gravity. The conditions of locomotion require the centre of gravity to move in as straight a line as possible, because force is required to displace it from that line. In draught-horses this defect is of no importance ; in animals used for other purposes it is detri- mental, and a mean obliquity of the sides of the croup is preferable. Other defects, not less serious, may result from an excessive inclina- tion of the lateral parietes of the croup, as is seen more particularly in the form in which it is designated sharp. Here the base of support is narrow and the hind limbs do not have their necessary freedom of movement during rapid locomotion ; they approach each other, the abduction is limited, and the animal will interfere or forge. Let us add that such a croup lacks strength and beauty, and is often accompa- nied by a narrow chest, sufficient cause to render the animal unfit for for some kinds of work. The absolute narrowness of this region is at all times regarded as a defect. Direction. The direction of the croup has been the theme of extensive discussions among authors who have written upon the exte- SUPERIOR FACE OF THE BODY. 131 rior. More recently, our learned colleague, M. Neumann, 1 has, in a full review of this subject, endeavored to offer diverse criticisms on certain views which we supported on this point in our first edition. These criticisms have induced us to make a careful revision of this part of our book, and we have conducted numerous experiments, the results of which are given in this edition. We are convinced that the diver- gence from our opinion regarding the direction of the croup, held^bysome writers, is much less reasonable than our critics imagine. They do not sufficiently consider the sources of error, and the compensations and exigencies demanded by the nature of the work which the animal must perform. Very often qualities or defects which belong to other elements of the conformation are attributed to the direction of the croup ; finally, it is common to see persons who choose as a standard of excellence such or such an inclination which has given good results in some instances, without reflecting that different purposes also require peculiar anatomical conditions, which endow the mechanism with a peculiar aptitude. The discussion into which we now enter will furnish the proof of what we have. said. First, how is the direction of the croup manifested ? Certain writers think, incorrectly, that it is indicated by a curve on the median line of the body extending from the termination of the loins to the origin of the tail. This line denotes only the degree of convexity of the sacral spine and the curvature of the sacrum. It is altogether independent of the general direction of the coxse, and influences but little the form of the region. The axis of the croup, in our opinion, corresponds almost exactly with a line uniting the angle of the haunch to the point of the ischium and passing some distance above the coxo-femoral articulation ; we will call it the ilio-ischial line. We are prepared to assert that the direction of this line depends upon two principles, as follows : 1st. It may depend upon the dimension of the ilio-ischial angle. 2d. It may depend upon the more or less inclined position of the coxae without variation in its angle. a. INFLUENCE OF THE DIMENSION OF THE ILIO-ISCHIAL ANGLE. Two causes are capable of modifying the size of this angle ; they may act alone or simultaneously. It may be the inclination of the ilium alone which varies, or that of the ischium, or, finally, that of both, which may vary at the same time. Let us examine each of these cases in particular. 1 G. Neumann, Sur la direction de la croupe ; in Revue vllo\\ '- ing considerations. Bourgelat first described this region as having for its base the whole of the ilium, including that part of the body ex- tending from the external angle of that bone to the coxo-femoral articu- lation. Many of his disciples, following his example, have made use of such expressions as long, short, narrow, wide, straight, and oblique haunches, terms which are still used in the veterinary world, but w r hose meaning is hard to determine, if we take them in their literal sense. It is easy to see that it is illogical to make such a distinction as to separate the anterior part of the coxa from the posterior, to call the one part a haunch and the other a croup, to examine separately structures which are so intimately united and so harmoniously blended in their nature and their anatomy. Accordingly, to avoid those repetitions and confusions which otherwise would not fail to spring up in our minds, the haunch is best regarded as only a secondary region of the croup, interesting us by reason of its particular forms, and, more especially, its blemishes. These are the reasons why we have imitated those of our predecessors who have not accepted the distinction established by Bourgelat. Diseases and Blemishes. The haunch may be the seat of exc.oriations and wounds of more or less gravity, and sometimes accompanied by severe com- plications. They are always found on horses which have been injured by passing through narrow door-ways, on those which have to keep the recumbent position for a long time after surgical operations or during serious diseases, upon a bed with insufficient litter, or, finally, in those which, suffering from violent attacks of colic, throw themselves on the ground. In other cases, the haunch is the seat of hcemafomafa (blood-tumors), cysts, abscesses, bruises, partial or total fractures. The latter are followed by marked deformities of this region ; one haunch is lower than the other, from the fact that the detached portion is carried downward and forward by the contraction of the muscle of the fascia lata and the small oblique of the abdomen. The lameness which exists at the outset of such an accident disappears at the expiration of a certain time, but the deformity will always persist. An animal which presents it is called hip-shot ; it has received a stroke from a broom. " Finally, it is possible that in young horses the centre of ossification which forms the tuberosity of the external angle of the ilium may become detached by the force of muscular contractions, as when the animal is forced J44 THE EXTERIOR OF THE HORSE. into a restrained position for the performance of a surgical operation, castration, for example ; thus may be produced an accident which, if it is not a fracture properly speaking, simulates it by its deformity and by its results." l CHAPTER II. ANTERIOR EXTREMITY OF THE BODY. A. The Breast, or Pectoral Region. Situation; Limits; Anatomical Base. The breast is a symmetrical region situated at the anterior part of the trunk, and limited in front by the inferior border of the neck, behind by the axillce and the inter-axillary region, and on each side by the arm. It has for its main osseous element the anterior extremity of the sternum, on which are inserted the sterno-hyoideus, sterno-thyroideus, sterno-maxillaris, and sterno-humeralis muscles, and these are separated from the internal face of the skin by an abundance of connective tissue. It contains the plate vein, situated in the gutter formed by the adjoining borders of the sterno-humeralis and mastoido-humeralis muscles, which can be located easily from the exterior, and on which phlebotomy is sometimes practised. Form. The configuration of the external surface of the pectoral region varies according to the subject, from the fact that the volume of the above-mentioned muscles leaves the trachelian appendix of the sternum more or less prominent. But little attention need be given to this prominence. Nevertheless, if it is very marked, the region is qualified as sharp. Sometimes the breast presents two deep depressions situated within the scapulo-humeral angles ; these depressions are due to a meagreness of the muscles or to a change in the direction of the scapulo-humeral angle. This peculiarity is very common in horses which are poorly developed, and the breast is then described as hollow, or sunken. Width. The width is the principal element to be considered in the examination of the breast, and, as Bourgelat has said, it should be proportional to the volume of the body or the general development of the animal. 1 H. Bouley, loc. cit. ANTERIOR EXTREMITY OF THE BODY. 145 Most authors have advanced the opinion that its width is propor- tionate with that of the chest. In our opinion, it is easy to see in this assertion the false interpretation of the fact (for the most part very well established) that narrowness of the breast accompanies a thorax of little capacity and slender limbs. It might be supposed, indeed, that there ought to be a certain relation between this narrowness and the space enclosed by the first two ribs. This is, however, an error which we have exposed by more than fifty observations made upon the living subject and completed after- wards upon the cadaver. We have never found marked differences in this respect among subjects of the same size, whatever may have been the width of the breast. This is due to the simple reason : it is not at the anterior extremity that the dimensions of the chest vary, but rather in the middle and posterior regions. Also, the differences in the width of the pectoral region are the result of causes other than the separation of the anterior ribs. We must attribute them to the varying thickness of the pectoral muscles which form its base. It is also true that -this region can accidentally become narrow in animals whose thorax is spacious. It is only necessary to place them in bad hygienic conditions, or to give them improper food and injudiciously-chosen work, to convince ourselves that emaciation causes a diminution of its width. It is physiologically true, however, that the general development of the respiratory apparatus is directly proportional to that of the muscular system. The functional activity of the muscles causes an augmenta- tion of their volume, and their contractions produce an increase of the amount of oxygen consumed. No lungs, no muscles ; and, conversely, dense and vigorous muscles require a spacious thorax ; whence it follows that the width of the pectoral region, owing to the volume of its muscles, should coincide with a certain degree of respiratory power. If, there- fore, this region is narrow, it becomes desirable to determine to what cause this narrowness is due, whether to that of the thorax directly, or to the animal's " condition." The size being equal, the breast of the English thoroughbred horse is less wide than that of the heavy coach-horse, whilst he is endowed with a chest equally if not more spacious. In this case the harmonious development of the locomotory apparatus must also be considered ; the power of the muscles, instead of being the effect of their thickness, is due to their length ; and the sternum appears more prominent than it does in a horse with thick muscles. Besides, these muscles are dense, firm, and habituated to repeated energetic and extensive contractions. 10 146 THE EXTERIOR OF THE HORSE. There are, therefore, two elements to be considered in the width of the pectoral region : whether it depend solely upon the volume of the pectoral muscles, or if to this cause is also added a well-developed thoracic cavity. In the former case, the width of the breast will vary according to the general condition and health of the animal ; in the latter, its variations, whatever they may be, cannot be presumed to be due to narrowness or feeble development of the thorax. The width should not exceed certain limits ; for when these limits are passed width of the breast becomes a defect, since it gives too large an area to the base of support. Horses endowed with speed should be well open in front, but their openness must not be excessive, because the lateral displacements of the centre of gravity can only take place at the expense of the velocity of the gait. The English thoroughbred is not too open in front, whilst his chest, which appears narrow, is high and salient in such a way that the extremity of the sternum is prominent and gives attachment to long muscles. Draught-horses can, without being defective, be very open in front. The lateral oscillations of the centre of gravity, being only prejudicial to velocity, do not diminish the energy of his efforts. His power depends upon his mass, and he demands, therefore, firm and volumi- nous muscles. From this point of view we may regard a wide breast as an absolute beauty, or as a point of great merit, because it gives to the trunk the volume which is necessary for it to have in order to overcome easily, but slowly, heavy resistances. When the breast is very narrow, it is said that the horse is closed in front. In all such cases, this conformation, the opposite of the pre- ceding, is defective. It indicates a feeble development of the muscular system, and very often respiratory organs of small amplitude. If such animals offer some appearance of energy when they are exercised, they are generally incapable of enduring continuous and laborious work. Narrowness of the breast, as well as its width, may be congenital or acquired. When it is congenital, it is observed in those subjects which, at birth, show themselves to be defective in the development of the muscular and the respiratory systems. When it is acquired, on the contrary, it is consequent upon a state of emaciation, exhaustion, diverse chronic diseases, and, in general, a profound debility of the organism. In this case, the extremity of the sternum becomes salient, the points of the shoulders project forward, and leave between them and the sterno- humeralis muscles two deep depressions which terminate inferiorly the jugular gutters. ANTERIOR EXTREMITY OF THE BODY. 147 Blemishes. The most common blemishes of the breast are traces of etons, but these need not arouse any apprehension, because people are in the habit of inserting these counter-irritants for the most trifling causes. More or less extensive cicatrices or denudations are also met here, which result from the application of revulsives and blisters in the treatment of diseases of the respira- tory apparatus. Finally, in draught-horses it is common to observe excoriations or cicatrices which extend from the inferior border of the neck to the anterior "border of the shoulders, following the direction of the collar. These have no important significance, and are even utilized by the horse-merchant to indicate to the buyer a proof that the animal settles freely into the collar. B. The Inter-axilla. Situation; Limits; Anatomical Base. The inter-axilla is a symmetrical region limited in front by the breast, behind by the xiphoid region, and on each side by the axillary space. It responds to the inferior border of the sternum and to the origin of the sterno- humeralis and sterno-aponeuroticus muscles. Having a variable conformation, concave or convex, according to the volume of the muscles, it presents nothing remarkable as regards the exterior. Setons are applied in this region, to which, in the majority of cases, no more importance need be attached than to the cicatrices which follow them. C. The Axilla. Situation; Limits; Anatomical Base. The axilla corre- sponds in situation with the point of junction of the supero-internal extremity of the forearm with the trunk. Limited in front by the breast, behind by the elbow and the xiphoid region, internally by the inter-axilla, and externally by the forearm, the axilla has for its anatomical base the sterno-aponeuroticus muscle and the muscular interstice situated between the adjoining borders of the sterno-humeralis and mastoido- humeralis, in which the vein of the axilla (brachio-cephalic trunk) is lodged. The skin is soft, pliable, and mobile. Little importance is attached to this region, viewed from the exte- rior. Nevertheless, in certain thin-skinned and fat horses whose skin in the axilla offers numerous folds, it presents, during the summer and after a long march on dusty roads, excoriations, accompanied by redness and great sensibility, which may prevent them from performing their duties for several days. This accident, frequent in cavalry horses, and generally of no gravity, is called fraying of the axilla. We may also allude to bloodletting from the brachio-cephalic vein, which is sometimes followed by a thrombus. 148 THE EXTERIOR OF THE HORSE. CHAPTER III. INFERIOR FACE OF THE BODY. A. The Xiphoid Region. Situation; Limits; Anatomical Base. The xiphoid re- gion corresponds to the inferior part of the sternum and the xiphoid cartilage (a tract whose approaches are flattened from above to below), at the level of which usually passes the girth of the saddle and the belly- band, when the thorax is properly suspended between the anterior mem- bers and the abdomen has a good conformation. If the withers are low or elevated, or the abdomen like that of the greyhound, these bands must be carried either forward or backward of their proper place. It is then understood without difficulty that the situation of the latter must be changed according to the circumstances. Limited anteriorly by the inter-axilla, posteriorly and on the sides by the abdomen and the ribs, and laterally by the elbow and the ribs, this region is more or less plainly marked, according to the subject, by a slight concavity which insensibly passes into the neighboring regions, and especially into the abdomen. It is of no great interest with respect to the information which it furnishes, but is, nevertheless, the seat of blemishes as well as of wounds. The blemishes are excoriations, cicatrices of variable sizes, and traces of revulsives and blisters, recent or remote, applied for therapeutic purposes in serious diseases of the respiratory organs. The diseases of the thoracic cavity which require the employment of such means may not leave any permanent alteration of the organs affected, but, at the same time, it is necessary to examine the thoracic organs carefully, as well as the movements of the flank. The wounds are generally caused by a harness which is misfitting or improperly applied. In saddle-horses, a girth whose tension is severe will, if it be too stiff, too wide, soiled, or exert unequal pressure, irritate the skin and render it extremely painful. It is then necessary to use one which is narrower, or made of softer material, as cotton, or lined with silk. In draught-horses the same wounds are caused by the pinching of the skin between the girth and the belly-band. These denudations disappear never to return when use is made of one wide girth, upon which one more narrow is fastened by means of two keeps. Other means, such as sheepskin with the wool on, and soft pads, are insuffi- cient, irritating, and difficult to keep clean. INFERIOR FACE OF THE BODY. 149 B. The Abdomen. Situation ; Limits ; Anatomical Base. In external anatomy this region corresponds to the inferior surface of the abdominal cavity. It is circumscribed in front by the xiphoid region; behind by the sheath and the scrotum in the male, and in the female by the mammary glands ; on each side by the ribs, the flank, and the groin. The structures which form its base are, proceeding from without to within, the skin, the panniculus carnosus, the tunica abdominalis, the abdominal muscles, and, finally, the peritoneum, the serous membrane which covers the parietes of the abdominal cavity, and the contained organs. Beauties and Defects. It is important to consider the region of the abdomen, for by its volume and its weight it influences loco- motion. By certain other characteristics it gives information as to the qualities of the animal and its state of health or of disease. We shall now discuss it as to the two following points, intimately associated with each other : the volume and the form. Volume. In a state of health the abdomen is elastic and yields to digital pressure. It augments in volume after a meal and diminishes in a measure when digestion is completed. It should be proportional to the size and the type of the horse. It varies according to the breed. Though larger in some and smaller in other strains, it is not on this account disproportional, comparatively speaking. In animals used for slow or rapid work, its vertical diameter, measured from the middle of the back, is most generally equal to the length of the head. It is always more voluminous in the light saddle- horse, the product of a half-breed and a pure-blooded animal, or of the latter stock alone, except during the period of training. It is, perhaps, most exact to consider, with M. Eug. Gayot, the volume of the abdomen as beautiful whenever this region continues the external form of the thorax, i.e., when the latter becomes insensibly continuous with the arch described by the ribs and the flank. Its inferior line, when viewed in profile, should describe a graceful curve from the sternum to the inguinal region. In this case it can be pre- sumed that digestion and assimilation are well performed, because the amplitude of the abdominal cavity corresponds to the volume of the enclosed viscera, which is in relation with their functional activity, particularly when the diet consists of aliments of good quality. When the abdomen is defective through lack of volume, it indi- cates an animal with impaired assimilation, whose digestive functions 150 THE EXTERIOR OF THE HORSE. are irregular and incomplete, unless this state be due to the mode of alimentation, or to the special functional gymnastics to which the race-horse is submitted. A too voluminous abdomen denotes an animal of a ravenous appe- tite, of common breeding, or reared in low and damp countries with coarse, very aqueous, and innutritions food. Being compelled to take a large quantity of these aliments in order to obtain the necessary nutri- tive material, the horse submitted to this regimen has a distended stomach and intestines which, pressing against the posterior face of the diaphragm, compress the heart and the lungs. The muscles remain feeble, flabby, and little developed ; the skin becomes thick and the hairs coarse; the form is thick and clumsy, and the constitution soft. The step is heavy, the respiration constrained by the weight of the intestinal mass. The pace is impeded by the lowering and forward displacement of the centre of gravity, and this fact renders the horse unable to execute even the least laborious efforts for any length of time. In young horses, from the nature and the quantity of the sub- stances which they ingest, the abdomen is ordinarily voluminous. They receive little grain, and their diet consists principally of dry forage and of grass which they obtain in pastures. In broodmares the abdomen is also more developed, either from the fact of gestation or from the peculiarities of their food. We do not believe, as some veterinarians do, that the volume of the abdomen has any influence upon the disposition of the horse. If certain subjects are irritable, whimsical, gentle, or quiet, their disposition pertains to their inherent nature, and not exclusively to the conforma- tion of such or such a part of the body. In fact, the exceptions to the rule proposed by the veterinarians we have alluded to are so fre- quent that it is not necessary to give this matter any further attention. Form. The abdomen, of which the form is in close proportion to its volume, is generally cylindrical in those animals that are well nourished. If its inferior line, instead of describing the graceful curve of which we have spoken, passes obliquely backward and upward, as we observe it in greyhounds, it is called greyhound-like. The horse which presents it is lank, deficient in the volume of the bowels and of the body, which possess poor assimilation ; too much air passes underneath the abdomen ; the digestive functions are imperfect. Arrived in the stable after a long drive, he stands back from the man- ger, sulks over his food, reads the newspaper, according to the language of horsemen, and is incapable the next day of resuming his work. INFERIOR FACE OF THE BODY. 151 This condition must not be confounded with that retraction of the abdomen which is temporarily the result of training in the horse, or of an exclusive diet of oats for those required to perform laborious services. If, on the contrary, the inferior line of the abdomen is very convex, descending abruptly backward from the sternum, it is spoken of as dropping, pendulous, or cow's belly. This is a conformation indicating, as we have seen, a horse with a ravenous appetite, sluggish, without activity, and predisposed to be sway-backed and short-winded. In breeding districts where the forage is nutritious and fattening, as in the Valley of Auge and in the Cotentin, it is not necessary to hesitate over a voluminous abdomen when the conformation of the chest is good, and particularly in the case of mares which are pregnant, and that of foals and colts. Diet and exercise will soon .cause its disappearance. The skill of the buyer consists in selecting under adverse circumstances, often with little to enlighten him, the animal which, in spite of a heavy abdomen, will with proper care assume a light, graceful, and stylish appearance. 1 Diseases and Blemishes. The diseases and blemishes of the abdomen it is important to recognize. They are : 1. CEdema, or a serous infiltration of the connective tissue, an enlargement of variable area, which is soft (but not hot or fluctuating) and yields (pits) to the pressure of the finger. It results often from prolonged rest in the stable, and sometimes also follows traumatisms, castration, or the application of irri- tating substances used with a therapeutic object. 2. Exomphalus, or umbilical hernia, very common in colts, which con- sists of a subcutaneous swelling from a protrusion of a portion of the intestines through the umbilical opening, whose obliteration after birth has not taken place. This affection is very rare in adults, because it is treated at an early period, and because it reduces itself spontaneously as the vertical diameter of the abdominal cavity increases. 3. Ventral hernia, which only differs from the preceding in that the rup- ture of the parietes through which the abdominal organ passes is accidental, and may be situated upon any part of the abdomen, instead of being natural and occupying always the position of the umbilical opening. It is due to rupture of the muscular and fibrous parietes of the abdomen. When the solution of continuity extends to the skin and the intestines protrude, it is called an eventration. The two terms do not carry the same importance. Although they are only different degrees of the same accident, yet, in relation to their gravity, they are not com- parable. 4. Traces of setons, which certain practitioners prefer inserting in this region rather than in the axilla or inter-axilla, so as not to interfere with the application of the girth and the belly-band. They have no importance. 1 A. Rivet, Guide pratique de 1'acheteur de chevaux, p. 71. 152 THE EXTERIOR OF THE HORSE. 5. Excoriations following vesicants or revulsives. These should induce the buyer to examine with care the state of the lungs, for these agents are some- times intentionally applied here to divert the attention from the place which should more particularly require their application. Let us say, finally, that in some instances the abdomen may be distended, tympanitic, and painful to pressure. These symptoms indicate acute or chronic inflammation of the digestive viscera, or the peritoneum, or the presence of diverse profound lesions which we shall here only hint at. CHAPTER IV. LATERAL FACES OF THE BODY. A. The Costal Region ; Ribs ; Sides. Situation ; Limits ; Anatomical Base. The region of the ribs is situated upon the lateral parts of the trunk, below the back, behind the shoulder and arm, in front of the flank, and above the xiphoid region and the abdomen. It has for its base the last twelve ribs, which are not concealed by the shoulder, and which are covered by the great dorsal, the great serratus, and the great oblique muscles of the abdomen ; the intercostal muscles, external and internal, fill the spaces which exist between them. Movements. In the normal state, the ribs execute regularly alternative movements of elevation and depression, more or less extensive according to the state of respiration and the numerous circumstances which modify its rhythm. These movements, especially perceptible under the skin of emaciated horses, are of two kinds : the first movement takes place during inspiration, and is explained by an augmentation of the intercostal spaces and the rotation of the ribs forward and their abduction from the median line ; it corresponds to the dilatation of the thoracic cavity and the lungs ; the second movement, coinciding with expiration, consists in the approximation of the ribs and in their rotation backward and inward ; it corresponds to the contraction of the thorax and the compression of the lungs. Form. Slightly flattened towards its superior part, and much more rounded as it is examined more posteriorly, this region presents two opposite conformations. The ribs are called round when they describe, as a whole, a well-defined convexity from above to below ; they are flat in the contrary disposition. Beauties. The due curvature of the ribs, their definite separation from each other, and their full development in length are three absolute beauties, or points of excellence, to be desired in all horses, whatever LATERAL FACES OF THE BODY. 153 may be their service. In explaining the reasons for this, we will show the inconveniences resulting from their flatness, their nearness to each other, and their want of length. FIG. 42. 1st. The normal curvation of the ribs is in direct relation with a large transverse diameter of the thoracic cavity, and, consequently, with the development of the respiratory apparatus. Before proceeding further, let us determine what is understood by the convexity of a curve. It is the relation which exists between the height of its arch and the length of its chord, supposing, be it well understood, that we are speaking of a regular curve. In other words, a curve is much more convex when it forms a greater projec- tion upon a shorter chord. Thus, the two arcs ADB, A'D'B' (Fig. 42), although belonging to two circumferences of the same radius (OA = / A / ), have not the same convexity relatively to the chord which unites them, for the arcs and their chords are differ- ed C'D' ent, and their relations, "Tip T//P are not e q ua l Again, the curve AOB (Fig. 43) is more convex than the curve AO C, although its height be equal, because the ratio ~TT> ^ greater than the ratio -~ Therefore, because two curves have the same projection upon their chord, it must not be concluded that their convexity is the same, this condition being realized only when the chords are equal. What we have just applied to the arcs can be extended to the ribs, although 154 THE EXTERIOR OF THE HORSE. complete similarity may not be possible, on account of the irregularity of their curvature and the variations of their length and form. Henry Cline long ago demonstrated 1 that the more the pectoral cavity deviates from a cylindrical form the more its capacity is di- minished. It results from this that the rib which presents the greatest curvature will also be the one which circumscribes the greatest space. Depress a cone or cylinder, and the reduction of their volume is in pro- portion to the flatness of their surface. The thorax may be regarded as a flattened cone ; and this is why we say : for an equal length of the ribs, the chest can never gain in height what it has lost in width ; or, in other- words, the convexity of the ribs is the first beauty, or point of struct- ural merit, to be sought for in a good conformation of this region. 2d. This is not all^ the ribs, as structural elements of the costal region, should also be llSlg, for this length of ribs constitutes, for an equal width of the chest, the thoracic measurement in the vertical sense. The volume of a solid depends upon the relation which exists between its three dimensions ; to be large, it is necessary that the dimensions should all be as large as possible. It is, however, interesting to know that the rib can make up by its length for the lack of chest-volume occasioned by its loss of con- vexity. This proposition, which appears to be contradictory, in prin- ciple, to that which we have just given above, is, however, very logical, as we shall see. In the preceding case we supposed the length of the rib invariable^ and only made its curvature variable. In the present case we inves- tigate the problem under its two aspects by modifying its data to find the compensations, if any exist. This method can be illustrated by the following comparison : Is there for two horses, the one having very round ribs and a low chest, the other, less convex ribs and a very high chest, any compensation in respect to the thoracic capacity ? Nearly all authors answer this question in the affirmative, and,, theoretically speaking, they are correct. Let us suppose the two ribs A OB and ADC (Fig. 44). Let us also remem- ber that they have not the same convexity, since the ratio is greater than , AB AC which indicates that the first is more curved than the second. A glance at the figure shows that not only does the rib ADC circumscribe a surface equal to that of the rib AOB, but one that much exceeds the latter. Here, then, are two animals having the same width of the chest and a different convexity of the ribs, for which there is more than a compensation. Another 1 Henry Cline, Trait sur la forme des animaux, published in the work of M. G. Lefevre de- Sainte-Marie : De la race bovine courte corne amelioree, dite Race de Durham, Paris, 1849, p. 325.. LATERAL FACES OF THE BODY. 155 form of rib, AOG, might be found, for example, circumscribing a narrower chest for which there would be a proper compensation. Such are the results which can be deduced from an examination of the figure. But unfortunately for the position of those who defend this opinion, there is here much difference between theory and practice ; and since, after all, we must view the horse as he is, and not as we desire him to be, we must say that the ratio existing between the height of the chest and its width does not vary to a great extent. In thirty-six horses of differ- ent races, measured in this respect, we have seen this ratio range between 1.125 and 1.468 ; it should have a mean of 1.273. It follows from this that the compensa- FlG. 44. tions offered by the chest in its height are not as valuable as we were at first sight tempted to believe, because of the harmonious relations which exist between the two diameters of the thorax. A flat rib is in most instances short ; a round one is more often long ; the thoracic cavity but little developed in one sense has many chances of being small in another ; this is especially the reason why a fiat side should be rejected. It would always be in defiance of the most elementary observation to say that the existence of pectoral compensations is to be absolutely denied. Such compensations are possible theoretically, and in practice they do exist ; but they are rare and very limited. If a large number of horses be measured, some are found having the same conformation and the same width of the chest, with a difference of only two or three centimetres in the height of the latter. Less commonly, horses are seen which present a diminution of, perhaps, one or two centimetres in the width of the chest, but which redeem themselves by an excess of three or four centimetres, at most, in the height. But these last are excep- tions so difficult to meet that we have reason to doubt whether the internal mensurations of the thorax would, in fact, give the proof of a real compensation. It is always true that the ribs, even if deficient in convexity, are still capable of circumscribing a spacious thoracic cavity, upon the sole condi- tion that they are long and their flatness is not very marked. The essen- tial point is to know when the defect will be compensated and when it will not be. This is a point which demands great practical skill, and 156 THE EXTERIOR OF THE HORSE. upon which many connoisseurs are led into error. We think that we are giving good advice to beginners in recommending them always to dis- approve of the flat rib, whatever may be its apparent length. In the presence of such a conformation they should not neglect to assure themselves, by a more complete examination of the other regions, of the state of development which the respiratory organs present. This is, in our opinion, the easiest and most positive means of recognizing the compensation, if any exists. Besides, the roundness of the chest-wall, often more apparent than real, may lead superficial observers into error. The volume of the muscles which cover the thoracic walls and the abundance of fat and subcutaneous tissue may have the effect of making the parietes of the chest appear more round than it really is, and of concealing the essential bony pieces which constitute its base and limit its internal cavity. 3d. The width of the intercostal spaces is a beauty, or point of excellence, of no less importance. When the ribs are well separated, the thoracic walls present a large surface, extending from before to behind, and circumscribing a deeper cavity. Their separation from each other coincides also with their great projection backward, and it is easily understood that the latter gives the measure of their projection forward during inspiration. The movements of the different parts of the thorax should be as extensive as possible, in order that the lungs may have sufficient freedom of action. Large intercostal spaces support strong inspiratory muscles, and, therefore, imply great possible dis- placement of the pectoral walls. To recapitulate, the beauty of the ribs resides : 1st. In their great curvature from the shoulder backward. 2d. In their length, or in the vertical extent of the thoracic pe- rimeter. 3d. In their strong projection backward. 4th. Finally, in their separation from each other. Defects. Ribs that are flat, short, little inclined backward, little separated, characterize a horse which is short-winded and without power, whatever may be his breed, his stature, his temperament, or his origin. In ordinary language, this vicious conformation is expressed by saying that the false ribs are short and the hoop-ribs are but little descended, or that the animal has need of ribs. Diseases and Blemishes. a. Horses which have suffered from a pro- longed sickness, and which for this reason have assumed the decubitus for a long time, sometimes present a flatness of the one or the other region of the ribs. LATERAL FACES OF THE BODY. 157 b. Those which have been affected with a serious pneumonia or a pleurisy, and to which repeated applications of revulsives and blisters have been made, often show along the inferior surface of the region denudations accompanied by large discolorations of the skin or the hairs. It is important, in examining such animals, to observe attentively the character of the cough and the movements of the flank, in order to be assured that these affections no longer exist. c. At other times there are cicatrices situated at the level and in front of parts covered by the saddle, and ^due to setons inserted for a therapeutic- pur- pose. These counter-irritants are directed vertically, or are slightly oblique from before backward and from above to below. When they are observed, or their traces are found, we should inform ourselves more completely as to the reasons for their application, and the present condition of the horse, according to the manner indicated below. d. Heavy draught-, light draught-, and saddle-horses offer also, on the parts which receive pressure and friction from the shafts, the pole, the traces, the saddle, and the girth, depilations, wounds, cicatrices, and sit-fasts, known under the name of corns, which are the result of wounds occasioned by these pieces of the harness. e. Finally, bony tumors may be seen upon the course of one or several of the ribs. These are traces of old fractures, usually situated upon the middle parts of the region. Nearly always they are complicated by contracting adhesions with the lung, through the existence of a localized inflammation of the pleura which covers the internal surface of these bones. Likewise, as Lecoq says, we have reason to fear, especially when several ribs have been fractured, that a super- vening affection of the chest may be aggravated by this cause. The Chest in General. We have now examined separately the regions which concur to form this vast cavity, and we shall next investigate it as a whole with regard to the correlation between its dimensions and its beauties. ; >" Definition ; Limits ; Anatomical Base ; Usages. The chest is that part of the "body which corresponds to the bony cage designated under the name of thorax. Bounded above by the withers and the back ; in front by the neck and the breast; on each side by the shoulder, the arm, the axilla, and the ribs ; below by the inter-axilla, the xiphoid region, and the abdomen ; and, finally, behind by the abdomen and the flanks, it has for its osseous base the following parts : a. On the median line and above, the bodies of all the dorsal vertebra. b. Laterally, the ribs and the intercostal spaces. c. Inferiorly, the superior face of the sternum and the cartilages of prolonga- tion of the ribs. d. Behind, the diaphragm, convex in front and pierced by three openings, traversed by the aorta, the oesophagus, and the posterior vena cava. Open in front to afford passage to the trachea, the oesophagus, and the vessels cf the head and anterior members, as well as to the important nerves, it has in general the form of a cone, with the base posterior and truncated obliquely from above to below, and from behind to before ; it is depressed upon its lateral faces. Its functions are complex and of three kinds : 158 THE EXTERIOR OF THE HORSE. Through the bony parts, it is primarily an apparatus of protection to the central organs of respiration and circulation. By the mobility which it possesses, it constitutes the most important agent in the respiratory mechanism. Finally, by its resistance, its connections with the spine, and the extent of its skeletal surface, it plays an important role in locomotion by furnishing numerous points of attachment to the muscles which belong to the superior sections of the thoracic members. To fulfil this last purpose, its first pieces are short, strong, straight, and but slightly movable, for their action woi^ld be very much disturbed by their relation with the shoulder and arm. The last pieces, on the contrary, are curved more and more, narrower, removed from the median plane, and leave .a wide space at the posterior part of the pulmonary lobes. Beauties. Although the chest-wall is far from being observable over its whole extent from the outside, it is possible to judge of its capacity with much precision. This knowledge is of the greatest im- portance, for it furnishes information upon the essential elements of the value of the horse. The chest may be called beautiful when it is high, wide, and long. Let us see the meaning which should be attached to these three words : 1st. Height. This is measured from the summit of the withers to the inferior surface of the xiphoid region ; this line, then, marks the true vertical diameter of the thorax, that diameter being greatest at the spinous process of the fifth dorsal vertebra, which forms, as we have seen, the culminating point of the withers. This dimension must not be confounded with the depth, which is measured from before to behind ; it is to be regretted that some hip- potomists have changed, in this connection, the meaning of a term established by long usage. 1 In speaking of the ribs, we have said that this height, with the corresponding width, is directly proportional to the length of these bony arches. When this height is considerable, the chest is said to be well descended, an epithet which depicts its situation relative to the ground. We must remember, moreover, that the extent of this thoracic dimension is one of the conditions of pectoral amplitude. It should, however, not be forgotten that this factor alone is insufficient to the development of the thoracic capacity ; the curvature of the ribs must also be taken into the reckoning. Leaving out of the account the length of the fifth dorsal spinal apophysis, the height of the chest is nothing else than the chord of the arch represented by the ribs. Mere height of the chest has no longer any importance but for the coexistent 1 The depth of a thing, says Littre, is the extent of this thing, considered from its entrance to its bottom. The entrance of the chest is situated between the first two ribs; its bottom is the diaphragm. Therefore, here, depth is synonymous with length. LATERAL FACES OF THE BODY. 159 curvature of the ribs. In fact, it is known that by depressing a cylinder its capacity can be reduced Avithout diminishing its surface. It is not correct to believe that the height of the chest is always proportionate to the height of the withers. We have already shown that the length of the spinal apophyses of this region is subject to numerous variations, and that the prominence of the withers often depends upon the mode of suspension of the trunk between- the anterior members. A horse whose chest has a good height should, according to M. Gayot, 1 measure a greater distance from the top of the withers to the interior face of the sternum than from this point to the ground. The first distance would exceed the second thirty centimetres in well-formed saddle- and driving-horses, with a height of about one hundred and sixty centimetres, whilst it might not be more than fifteen or twenty centimetres in animals of an inferior conformation. We must acknowledge that we are still ignorant of the exact pro- portions. Not only is the distance between the ground and the xiphoid region not equal to the height of the chest, but the latter is always several centimetres greater ; the difference may even be twenty centi- metres. Our measures have been made with the aid of the metrical standard and the compass of depth upon more than fifty horses of all varieties, slow and rapid Avorkers, saddle- and race-horses, etc. ; they have been taken upon common horses, Percherons, Boulonnaise, Bel- gians, Bretons, Normans, Berrichons, Andalusians, Barbs, Tarbans, and English thoroughbreds. It is scarcely necessary to add that this height must be examined from, the side of the chest ; it Avould be impossible to appreciate it accurately by vieAving the region from any other direction. The chest, to be high and well descended, should extend Avell beloAV the summit of the elboAv. 2d. Width. The width of the chest is the result of the curva- ture of its osseous parts. It is measured from the middle ribs to those which correspond to them upon the opposite lateral plane. To do this, the observer is stationed in front of the animal, so as to see the profile of the ribs and the degree in which they project beyond the shoulders on the right and the left. The roundness of the ribs is also judged by vieAving the horse obliquely, either in front or behind. It is not necessary to refer here to the advantages of a large trans- verse development of the thoracic cavity, but Ave would caution the 1 L. Moll et Eug. Gayot La connaissance generate du cheval, Paris, 1861, p. 137. 160 THE EXTERIOR OF THE HORSE. reader against certain ideas which are too absolute, and which exist among horsemen. Some prefer the cylindrical chest for slow and heavy motors ; they reject it, on the contrary, for rapid services, in which they would prefer the elliptical form. The latter form, whilst giving equal space within the chest, tends to limit the lateral displace- ments of the centre of gravity, and thus facilitates the velocity of the gait. Others insist that there is sufficient compensation between the two forms, but consider width of chest as a beauty, or point of merit, in all cases. We have seen, when speaking of the ribs, that a high chest is spacious only on account of its proportional width, but the relation between the vertical and the transverse diameters varies less than is generally thought. The development in one direction very often carries with it a correlative development in the other. The digressions which seem to contradict this principle are more apparent than real, for the condition of the body has much influence upon the external dimensions of the chest. Take a horse in good health, vigorous, well proportioned, and subject him to excessive work and insufficient food, and measure his chest when emaciation has reached its extreme limits. Not only is he unrecognizable in his general form, but his narrow thorax and his flat ribs have modified the correlation of his two thoracic diameters, and we shall be astonished to find it to be 1 .4, Avhen, for example, it was 1.2. When the animal is ill cared for, when good nourishment and moderate exercise no longer maintain the harmonies of the economy, all the functions are diminished, especially those of respiration and circula- tion. The chest tends to become contracted, at the same time that the muscles become smaller, for the lungs are less active in the animal which is emaciated. To make a contrary experiment, take the same horse and entirely change his conditions of existence ; his chest will* reassume its form, according as its muscles augment in volume, density, and energy. The training which animals destined for the race-course undergo, and that which results from the special labor to which work -horses are subjected, constitute, again, important causes of a development of fulness of the chest. In the horse, as in man, muscular gymnastics have the effect of increasing the thoracic perimeter. If we were not convinced of this fact in practice, our purchasing officers would every day refuse horses whose chest is not perfect at the moment of the sale. Our remounts take them because they know that this defect will partly dis- appear after sufficient exercise. Thus, in our opinion, amplitude of all the thoracic diameters should LATERAL FACES OF THE BODY. 161 be desired, whatever may be the service required, for they are correla- tive to one another. The variations, in this respect, are so insignificant that they do not deserve to be taken into consideration. The English thoroughbred horse differs essentially in his form from the heavy draught-horse, but the relations of the three dimensions of his chest are sensibly the same as in the latter when both have a spacious lung. All proportions considered, the rib seems perhaps a little longer und less , convex ; what tends especially to make it appear thus is the particular nature of the tissues and muscles which cover it. 3d. Depth or Length. The length of the chest is measured from before backward, from the angle of the shoulder to the middle part of the last rib. It is easily appreciated by examining the horse in profile. It depends upon : 1st, the width of the intercostal spaces ; 2d, the degree of projection of the ribs behind. The chest may be deep without the back acquiring an immoderate length. In fact, ribs very much arched and strongly oblique behind and below cause the thoracic cavity to encroach in a certain proportion upon the abdomen. Nevertheless, as the width of the intercostal spaces is in direct ratio with the length of the dorsal region, it follows that a long chest is incompatible with a short back. The English horse pre- sents a very fine chest when he is well formed, and he generally trans- mits this beauty to his descendants as well as to the offspring of his crosses with our native horses. Defects. When the chest is deficient in height, the horse is said to be too far from the earth ; he has no chest, no xiphoid region ; too much air passes under his abdomen ; he is wanting in girth ; his sides or fake ribs are short ; his hoops are not low enough. When the chest is wanting in width, it is said to be narrow ; it is short, on the contrary, when it is wanting in length or depth. Finally, when it is deficient in its three dimensions, the animal lacks or has no insides. In describing the inherent beauties of a large development of the chest we have, at the same time, demonstrated the inconveniences of its defects ; it is, therefore, not necessary to return to the latter here. To recapitulate, the chest, to be beautiful, or ideally perfect, should be high, wide, and long. The relation existing between its different diameters varies but little in horses of the same race. The differences depend in most instances upon the state of fatness or emaciation of the animals, or upon improper exercise and training. 11 162 THE EXTERIOR OF THE HORSE. In a general way, the chest is or is not spacious, the harmony of the whole implying only that an increase in one direction is ordinarily followed by an augmentation in the others. It is from this point of view, especially, that animals differ in regard to their thoracic capacity. Exceptions are always found. Certain horses are deficient in one or another of the diameters, most often in the width. In such cases compensations are possible, but within a very small limit. They are always very rare and very difficult to estimate. We must not, then, allow ourselves to be misled by appearances ; we should form our judgment on a complete examination of the respiratory apparatus. B. The Flank. Situation ; Limits ; Anatomical Base. The flank is a double region, situated behind the ribs, in front of the haunch, the thigh, and the stifle-joint, below the loins, and above the abdomen, with which it is continuous. Its principal base is the small oblique muscle of the abdomen, with a portion of the great oblique and the transverse. Divisions. Three divisions are recognized, more or less distinct according to the individuals and the conditions in which they are placed ; the names which have been given to them indicate quite accu- rately the special configuration which they present. The first, external to the lumbar region and in front of the haunch, is called the hollow of the flank, because it presents a depression so much more distinct as the intestinal mass is heavy and farther removed from it. It is very pronounced in horses with a pendulous or cow's abdomen. The second division, or cord of the flank, corresponds especially to the fleshy part of the small oblique muscle of the abdomen. It forms a rounded relief, oblique, downward and forward, which extends from the angle of the haunch to the cartilaginous circle of the false ribs. Finally, the third division, the most inferior of all, known by the name of the movable portion of the flank, is united to the stifle-joint by a very mobile cutaneous fold, and becomes insensibly continuous with the abdomen. Three things are to be examined in this region : its form, its extent, and its movements. 1st. Form. When the flank is well formed, its hollow is but little observed, its cord is scarcely prominent, and its movable part continues regularly with the external surface of the abdomen and the last ribs. A flank of this description is seen in animals that are well fed and in a proper state of flesh. LATERAL FACES OF THE BODY. 163 When its concavity is too deep, it is said to be hollow, as may be observed in horses that are indolent, of a lymphatic temperament, and of large form and pendulous abdomen. It is also seen in meagre animals, and in those which are poorly nourished, or which have been obliged to endure great fatigue or a long period of sickness. It is called corded when its cord or middle part projects above the two others, through the simultaneous effect of the depression: of one and the retraction of the other. This state is noticed under the same circumstances as those which cause the hollow flank, of which we have just spoken. When the inferior part of the flank becomes abruptly continuous with the abdomen, and appears as if pushed back towards the sub- lumbar region, it is said to be tucked up. Some authors also call it a greyhound flank when it becomes a permanent retraction, the tucking up being, in their opinion, only a transient disposition, always dis- appearing under an appropriate regimen. The greyhound flank, on the contrary, constitutes a veritable defect, being " an indication that the animal does not eat enough, which is the fault of a poorly-developed appetite ; it is impossible to repair in a just measure the waste caused by the action of the apparatus of locomotion, and as, by a singular contradiction of nature, greyhound horses are usually endowed with great energy, they are exposed to an early ruin if they are not used with care, since the losses which they sustain are only slowly repaired." * Finally, if the flank unites the three preceding vicious conforma- tions, if, in other words, it is hollow, corded, and tucked up, the animal is said to be thin, poor. 2d. Extent. The extent of this region is estimated by its width, measuring from the angle of the haunch to the last rib. This measure- ment should be as small as possible, and a flank of this kind is said to be short or narrow. Let us see the reasons for this. Most hippotomists assert that the width of the flank is in direct relation with the length of the loins, and that the measure of the one gives correctly that of the other. This assertion can be considered only as relatively true, for the reason that the last rib, on account of its projection backward, does not end where the lumbar region begins. No doubt the width of the flank will, to a certain degree, depend upon the great or small extent of the loin, for the rib comes more or less near to the haunch. In order that this last proposition should become rigorously true, it would be necessary that the length of the loins 1 H. Bouley, Nouveau dictionnaire pratique, etc., t. vii. p. 54, art. " Flanc." 164 THE EXTERIOR OF THE HORSE. should correspond always to the width of the flank, which, as we have just stated, is not the case. A more exact relation then remains to be established : it is that this width is the consequence of the depth of the chest first, and the length of the lumbar region afterwards. The latter varies much less than is generally believed in horses of the same size and race. It is quite otherwise with the former. When speaking of the chest, we have seen that the different depths of this cavity depend especially upon the degree of backward projection of the ribs, supposing a constant length of the back. The shortness of the flank indicates a deep chest, short loins, and well-developed muscles ; it is in these features that its beauty resides. All are in accord upon this point. Horse-dealers do not fail to show, by placing two fingers flat upon the region, that the animal has only two fingers' width of flank. It seems useless to detail the disadvantages of a contrary conforma- tion. It is evident that too much area is a defect, indicating, at the same time, the mobility and lack of solidity of the loins and the want of capacity of. the chest. In this case the flank is said to be long. 3d. Movements. Composed exclusively of soft structures, and attached to the last rib, whose movements, normal or abnormal, it fol- lows, the flank is indeed, as has been said, the true mirror of the thoracic cavity. In ordinary conditions, when the horse is at rest, it rises and falls r alternately recedes from and approaches the median line, as the air enters the lungs or is expelled from them. During inspiration its cord is- effaced, its hollow is depressed, its inferior part enlarges, descends, and is confounded with the hypochondriac circle. During expiration, on the contrary, its cord is quite apparent, its hollow is less deep, its- movable part ascends, is retracted, and increases the prominence of the false ribs. These movements should be executed regularly, slowly, without any jerks, and should succeed each other at almost equal intervals. Let us, however, notice a very correct observation of J. Girard, ignorance of which might lead one into error : after six or seven equal respira- tions a longer one occurs. The number of respiratory movements of the flank varies according to the age, the seasons, and the physiological condition ; but its mean may be estimated at twelve or fourteen to the minute. It increases with exercise according to the duration, extent, rapidity, and intensity of the efforts which the animal has been obliged to make. We have determined it to be eighty-seven after a gallop of about half an hour. This number LATERAL FACES OF THE BODY. 165 is always much greater immediately after than during the exercise. This results from the fact that the thorax furnishes numerous points of attachment to the muscles of locomotion, and thus loses its rigidity during work, precisely in the measure necessary to assure pulmonary oxygenation and avoid asphyxia. After a race, on the contrary, the muscles which extend from the thorax to the members no longer act; and the ribs need preserve no longer the same fixity ; the respiratory movements are now as much accelerated as they were before separated. All horses do not have exaggerations of the respirations in the same proportion after exercise ; some become breathless much more quickly than others. We shall explain this fact when we discuss the depth of the chest. However it may be, the horse which remains " winded" a long time after exertion lacks endurance, is said to be panting, or short-breathed, and usually has a narrow chest and a tucked-up flank. Examination of the Flank. We often limit ourselves to a superficial examination of this region, but this practice is wrong, for it is one of the most important regions of the surface of the horse's body. To avoid any doubt as to the regularity of its movements, two ex- aminations should be made : the first in the morning and when the horse .is at rest, and the next after a certain amount of exercise. It will be well in both cases to give the animal several handfuls of oats. These are the reasons for this procedure : at rest and in the morn- ing the respiratory movements are less frequent; the horse is not excited, and at this time he presents the most regular and most normal manifestation of his functions. After light exercise, the respiratory movements are increased, and those of the flank are more numerous and more intense, and sometimes reveal respiratory diseases which would have remained unperceived had not the organs themselves, so to speak, been obliged to show, by a greater activity, their physiological imperfections or their pathological alterations. Finally, the few hand- fuls of oats which the animal eats have the effect of turning his attention away from the persons or things which surround him. In summer it will also be well to free him from all insects which may torment him. The observer should place himself in such a position as to view the flank obliquely, in order to distinguish better its profile. He may be stationed either in front, one metre from the shoulder, or behind, and at the same distance from the croup ; the eye will then follow with care and ease the oscillations of the lower part of the flank at the level of its attachment to the cartilages of the false ribs. The examination 166 THE EXTERIOR OF THE HORSE. will be made successively upon the two flanks, for it is sometimes accomplished better on the one side than on the other. The purely anatomical explanation which has been given for this is not sufficiently satisfactory to arrest our attention here. It will be possible, with the aid of these precautions, to determine "the modifications of number and rhythm of the movements without much difficulty. However, it is necessary to have a certain amount of practice and possess some knowledge of the different diseases which may aifect this region, for it is a question of slight variations, sometimes scarcely apparent, the appreciation of which requires the co-operation of an expert. Among the most common alterations of the flank there is one which is quite compatible with all the apparent signs of health, and which frequently escapes detection up to the moment of sale ; it is that due to pulmonary emphysema, an alteration which produces characteristic lesions in the lungs, consisting of an infiltration of air into the paren- chyma of those organs. This lesion, clearly proved, is redhibitory, and nullifies the contract of sale or exchange, according to the terms of Article 2 of the law of August 2, 1884. The expiratory movement in the emphysematous horse is double, and is separated by a short interval of time (hence called double time), during which the flank suddenly expands, and stops for an instant, to continue again its former expiratory movement. This double expiratory effort is more or less apparent according to the stage of the disease. However this may be, as soon as the disease has been detected, the animal should be made to cough by compressing the origin of the trachea. If the cough is dry, slight, abortive, and several times repeated ; if the nostrils are much dilated after exercise ; if they are both covered in cold weather with a grayish discharge adhering to the ala ; if the chest has an abnormal resonance on per- cussion ; if the movements of the flanks cause the entire body to move, particularly the anus; if labore dbreathing is rapidly developed in warm weather, the respiration loud, the anxiety extreme, etc., the exist- ence of a very advanced case of emphysema may be positively affirmed. Unfortunately, these characteristics are far from being always evident at the time of the sale, and they very often pass unperceived by inexperienced persons. By placing such animals in special con- ditions of alimentation, by submitting them to a particular mode of treatment in which arsenious acid plays an important part, merchants can sometimes conceal the disease, or, at least, mitigate it in a notable degree. The purchaser cannot be too exacting as to the integrity of LATERAL FACES OF THE BODY. 167 the movements of the flank, nor too much discredit all the more or less specious reasons which the seller never fails to give, in such cases, in opposition to any unfavorable assertions concerning the horse. Diseases and Defects. The flanks may be the seat of tumors of diverse nature. Sometimes these are indurations of the skin, a kind of callosities pro- duced by the ring of the breeching in shaft-horses; at other times they are abscesses, which are caused by the continual rubbing of that part of the harness. They may be the result of a ventral hernia, a portion of the intestine being expelled from its cavity on account of a rent in the abdominal walls. Finally, they are due to the presence of farcy-buds or lymphatic cords which cross the flank to reach the ganglia of the inguinal region. " The frequent expulsion of gas from the anus, which takes place in emphy- sematous horses, has induced ignorant horsemen to make an artificial fistula above or upon the side of the anus, by which they pretend to relieve the horse of the great quantity of air which he has in his body. At present this ridiculous operation, which formerly annulled the redhibitory action in regard to horses upon which it had been practised, is abandoned." * The special object of this procedure, of which we have seen some examples, was to prevent the noisy expulsion of gas through the anus by giving it a more direct outlet, in order to conceal to a certain extent the severe emphysema of which it is one of the symptoms. C. The Groin. Situation; Limits; Anatomical Base. The groin, which until now has not been comprised among the regions of the exterior, nevertheless deserves to be pointed out, on account of the examination which should be made of it. It corresponds on each side to the cutaneous fold extending from the abdomen to the thigh, and has for its base the inferior inguinal ring, which, as we know, gives passage, in the male, to the testicular cord and the external pudic vessels, and, in the female, to the mammary nerves and vessels. The superficial inguinal ganglia are also seen here on the side of the abdomen ; much more deeply, and on the side of the thigh, the elongated group of deep inguinal ganglia, less directly explorable than the preceding ; finally, the part is covered by a fine skin, with downy hairs, oily to the touch, usually black and very pliable. Limited in front by the abdomen, behind and externally by the superior and internal extremity of the thigh, internally by the scrotum, or the mammce, this region presents, properly speaking, neither beauties nor defects. We need only assure ourselves of the absence of blemishes. In undertaking its exploration, some precautions must be taken, especially in irritable horses. In examining the right side, for instance, the observer, after having warned the animal, will station himself i Lecoq, Trait< de I'extSrieur du cheval, 5e 6d., p. 92. 168 THE EXTERIOR OF THE HORSE. opposite the flank, apply his left hand to the croup, and with his right seek the inguinal ring, taking care to avoid being injured by the pos- terior member. If the horse is very sensitive, and attempts to rear, bite, or kick, an anterior member or the left posterior should be raised. The manoeuvres are of the same nature, but of an inverse order, when the groin of the opposite side is explored. The principal alterations which are observed in this region are enlargements known by the name of glands, which involve the superficial inguinal lymphatic glands, and whose presence often coincides with the existence of a glanderous diathesis. It will be prudent in such a case to examine the corresponding mem- ber, as well as the surface of the body, and, particularly, the course of the lymphatics, to see if no other symptoms of farcy exist, such as cords and buds. Inguinal hernia is sometimes observed in the groin, which enlarges the tes- ticular cord and no longer permits the different parts which compose it to roll under the fingers. We will refer to it again when treating of the scrotum. CHAPTEE V. POSTERIOR EXTREMITY. A. The Tail. Situation ; Limits ; Anatomical Base. The tail is a long, flexible appendix, situated at the posterior extremity of the trunk, limited in front by the croup, below by the anus, and laterally by the point of the buttock. This appendage is an ornament to the horse in the same manner as the mane, and is of great utility in protecting him against insects. It has for its base the coccygeal vertebrae, as well as the four pairs of coccy- geal muscles, which cover their surface. These muscles endow it with movements of elevation, depression, and lateral inclination ; the skin which covers them, and which is very adherent, is furnished with long hairs over its whole surface, except upon its inferior face and at the level of its base. Two divisions are recognized in this region, the stump and the hairs. Attachment and Carriage. The tail should be strong at its origin, commencing high up on the croup, and be harmoniously sup- ported during locomotion. It is then said to be well attached and well carried. When it does not present this uniformity of character, it is POSTERIOR EXTREMITY. 169 called badly attached, or badly carried. Often in very energetic horses, during work, it is concave superiorly, and even retro verted forward, which is expressed by saying that it is of trumpet form. Some persons call it rabbit's tail, planted as in an apple, when it originates almost horizontally from a very oblique croup. It is easy to understand that its attachment and its carriage depend upon the direction of the croup. When the latter is horizontal, the animal carries this organ with elegance ; with an oblique croup, on the contrary, the tail is poorly sustained, being applied against the buttock. According to its good or its vicious position, admirers of horses draw, in a manner entirely empirical, an accurate conclusion as to the energy and -vigor of the animal. The explanation of this opinion is found in the fact that when the elevator muscles are well developed and have a dominant action over the depressors, it is an excellent sign in subjects whose general muscular system is strongly developed. As horses of the finer races have the sacrum rectilinear from before to behind, whilst those of the common races have it usually convex in the same direction ; as, besides, this direction of the bone has an influence upon that of the croup, and, therefore, upon the carriage of the tail, we must guard ourselves against forming the conclusion that the beau- tiful attitude of the latter is in all cases the expression of great energy. Formerly, dealers and owners frequently attempted to remedy the ungraceful carriage of the tail by excising a part of the depressor muscles so as to allow the elevators their full degree of action ; this procedure was simplified by amputating a more or less considerable portion of the stump. This was the operation on the tail after the English fashion ; the animal which had undergone this operation was said to be docked in the English style ; it gave him a certain degree of distinction. Cutting the depressor muscles alone, the stump being spared, was called nicking ; the horse was then nicked. This custom is very old, for Hartmann 1 reports that the council of Calchyd, meeting in England towards the end of the eighth cen- tury, prohibited the practice of thus docking horses, on the ground that it was a barbarous custom. 2 There is no doubt that from this usage was derived the nickname Caudati, which w r as given to the Eng- lish in the thirteenth century. 3 The procedure did not long prevail in England before it passed into Germany. 4 1 Hartmann, Trait des haras, p. 274. 2 Journal de Paris, ann6e 1787, Nos. 201 and 216. 8 Dufresne, Glossar, word " Caudati." * Neue Kriegsbibliothsk, Breslau, 1771, 8vo, 6th part. 170 THE EXTERIOR OF THE HORSE. It is not in place here to speak of the different accidents which may be the consequence of docking ; they are quite numerous, and more or less serious. It is sufficient to say that the operation is not always without danger. Many docked horses carried their tails either to the right or to the left side, like certain terrier dogs. This resulted from raising the tail upon the croup after the operation, and maintaining it there by sup- porting it by its superior face upon a pad of straw. The latter often became disarranged during locomotion, was displaced backward and forward upon the croup, and rendered the cicatrization irregular. State of the Stump. The stump has the form of a quadrangular pyramid, whose summit corresponds to the free extremity ; its inferior face is normally always devoid of hairs. The tail whose stump is intact is called entire ; it is said to be docked, when a portion has been amputated from the latter. We should not neglect to note the one or the other of these conditions when a description of the animal is required. Some persons attach importance to the development of this part, because it is generally in harmony with the other muscles of the body. It is also customary to raise it at the time of the sale, and to estimate the vigor of the animal according to the degree of resistance which it opposes. As H. Bouley affirms, " the information furnished by this measurement of force seldom leads into error." l State Of the Hairs. When the tail is entire, its stump, intact, naturally carries all the hairs which it can support. At present the horse is said to have a full mane and tail when they have not been shortened. In such cases, their abun- dance and their length vary much according to the race and the subject. It is known that in Arabian horses the hairs of the tail often touch the ground ; in others, they usually stop more or less below the hock ; they are always disposed in a point inferiorly, like the bristles of a brush. FIG 45. It is rare that they are preserved in this state. They are usually shortened in different ways; they are divided transversely, sometimes on a level with the chestnuts or the point of the hock, sometimes towards the fold of the buttock. In the description, this kind of section should be indicated in the following manner : entire tail, shortened hairs. All race-horses are thus treated i H. Bouley, Maison rustique du XIX stecle, 1, ii. p. 203. POSTERIOR EXTREMITY. 171 (Fig. 45). The tail is then more easily turned up, it soils the rider less, and is much less liable to cateh the reins, an accident often serious on account of the energetic kicking which it at times provokes. As soon as the stump has been shortened, it is plain that a certain number of hairs are wanting ; the horse can no longer be described as having a full tail. Special designations have been employed which recall the particular disposition of the hair upon the horse's tail. When, for example, after amputation practised upon the stump, the remaining hairs preserve their entire length, the tail is like a broom (Fig. 46), on account of the aspect it presents ; inferiorly it termi- nates in a tapering point, like a paint-brush, as in horses with full mane and tail. When it is too long, it is sometimes shortened with the knife, but its form is preserved. It is usually allowed to have its full length in draught-horses. If, after the amputation of a portion of the stump, the hairs are cut transversely at the level of the fold of the buttock, or slightly below, the tail, still quite long, is called banged. Such is the custom adopted in the army, and in horses performing light work, coach-horses, etc. At present it is becoming more and more fashionable to have the tail very short in certain horses kept for pleasure, principally Irish cobs, race-horses, and ponies. It then scarcely extends beyond the point of the buttocks. Three principal forms are given to the tail by the manner in which the hairs are cut ; besides, it has not the same aspect on the animal FIG. 46. FIG. 47. when at rest as when at work, in profile as behind, as is shown by the figures. It is called a short tail when the hairs have been cut off per- pendicularly to the stump and close to the latter (Fig. 47). 172 THE EXTERIOR OF THE HORSE. Sometimes the hairs are cut obliquely from below upward and from behind to before (Fig. 48). FIG. 48. Finally, the tail is called bushy when the hairs, a little longer than the stump, are excised obliquely, as in the preceding form, but follow- ing a convex curve, which is insensibly continued on each side to join the root of the stump. When well supported, it resembles the brushes which bakers use to clean loaves of bread (Fig. 49). FIG. 49. Formerly, the name club-tail designated one whose stump, with the hairs removed in the middle, cut very short, presented upon the sides two long locks which were allowed to flow freely. The origin of this appellation being much disputed, and, besides, being of little interest, we will say nothing more about it. This form of tail is no longer fashionable. However, Lecoq reports that it is still sometimes seen in tow-path horses. 1 Finally, the horse is said to be rat-tailed when the hairs, thinly scat- tered, render the partly-denuded skin of the stump visible. Although a proverb asserts that never does a horse with rat-tail leave his master in trouble, this peculiarity should always be considered as an inconven- 1 Lecoq, Ext6rieur du cheval, p. 73. POSTERIOR EXTREMITY. 173 ^ ience, on account of the function devolving upon this region, especially in broodmares ; it is rejected in services of luxury, on account of the ungraceful appearance which it gives to the animals. We have already said, in speaking of the mane, that horses with a gray or white coat, with curled woolly mane, always have melanotic deposits in the interior of the body. This state of the mane is extended also to the tail, and constitutes a cause of depreciation so much greater as it is more accentuated, for melanotic tumors often cause the most serious complications. Merchants have the habit of plaiting the tails of their horses when the hairs are very long, principally in those of heavy draught, before they present them for sale. This practice, intended to give greater apparent width to the posterior part of the trunk and to make the posterior quarters appear more prominent and vigorous, is generally accompanied by a small fraud, which consists in introducing a piece of ginger into the anus. Suddenly the animal feels very energetic, a feeling which he manifests by the elevated carriage of his tail and the vivacity of his movements. We will return to this custom when speak- ing of the animal at the sale. A more serious fraud, the employment of which, however, is, rare, is the application of a false tail to horses with a rat-tail, for example, or in the case of a pair of horses in which this region is dissimilar. If any doubt is entertained as to this manoeuvre, it may always be detected by unpiaiting the tail and withdrawing the straw and other accessories which jockeys employ when the horse is to be sold. When the tail has been the seat of operations practised by dealers, it is useful, at the time of buying, to be guaranteed as to the pos- sible results. On two occasions we have seen animals die of tetanus following amputation of this organ, performed by the seller. In relation to its movements, the tail, during work, should be carried high and remain immobile. If it is agitated in a jerking way, the animal switches the organ, as seen in urinating, ticklish mares when the posterior parts of their bodies are touched or approached. Care should then be taken against kicks and bites ; the attitude of the ears and the expression of the physiognomy afford information concerning the intentions of the animal. Let us remark, in conclusion, that the horse threatened or struck from behind instinctively depresses the tail between the buttocks. It is often sufficient to seize him by this appendage and exercise upon the hairs strong traction from above downward, to prevent him from rearing. 174 THE EXTERIOR OF THE HORSE. One of the most frequent diseases of this region is pruritus, occasioned by the uncleanliness of the skin of the stump, sometimes by the presence of intes- tinal worms (oxyures), or the itch, which is manifested by depilations, excoria- tions, and eschars, more or less extensive. These affections always begin by a peculiar straightening of the hairs, which should attract the attention of the purchaser ; otherwise they are not serious. The crupper quite frequently causes wounds when it is not well fitted or padded, especially in animals low in front, in which the saddle and harness have a tendency to slip towards the withers. These lesions are also observed on horses of a good conformation which are harnessed without the breeching, and which are required to descend steep hills. However caused, these wounds sometimes make it impossible for the animal to endure the crupper. We have seen them so deep that they could take the place of nicking. Generally it is sufficient to increase the thickness of the crupper or to discontinue the use of this part of the harness, to enable the sores to heal at once. We shall further on speak of cicatrices, longitudinal or transverse, traces of docking or nicking ; of fistulse which require a long time to heal, and which com- plicate these operations ; finally, of melanotic tumors, sometimes ulcerated, which cause a black, fetid, and unclean discharge. B. The Anus. Situation ; Limits ; Anatomical Base. The anus is the posterior orifice of the digestive tube. Situated underneath the tail and above the perineum, it has for its base the most posterior muscular fibres of the rectum, surrounded by a strong sphincter, related on the sides to two retractor muscles (ischio-anal). Its skin is fine, pliable, oily, devoid of hairs, and black even in white horses ; we can some- times find, however, as in the vicinity of other natural openings, pinkish surfaces deprived of pigment, called leprous spots. Internally it is covered by the rectal mucous membrane. In vigorous and healthy horses the anus forms a rounded projection, firm, depressed, and folded at its centre like the mouth of a purse ; it is described as prominent. In animals weakened by age, work, and sickness, it appears sunken, soft, and sometimes gaping. It shows, in this case, its mucous interior, and becomes powerless to retain the faecal matters, which poorly moulded, on account of the general atony of the digestive tube are expelled with much gas during locomotion or while the animal is taking a deep inspiration. This state is characterized by giving the animal the epithet evacuator. Diseases and Blemishes. The anus is especially to be exam- ined in regard to its alterations. Let us speak first of the melanotic tumors in certain white or gray horses, the volume of which is an obstacle to the expulsion of the excrements. These POSTERIOR EXTREMITY. 175 tumors soon soften, ulcerate, and acquire a repulsive aspect and an unpleasant odor, and they lead to fatal results whenever sufficient inflammation is excited. Anal fistulas were quite common at the time when the operation of docking the tail was more usually practised, of which they constituted one of. the compli- cations. It was not less frequent to find here other fistulae which were voluntarily made, under the name of whistle, or nightingale, with the object of relieving horses affected with emphysema, in which the expulsion of gas through the anus is almost constant. As we have shown on a previous page, this practice_has long since fallen into disrepute, and is now only the appendage of a gross empiricism. In certain horses a particular larva is sometimes found, attached strongly to the margin of the anus by the hooks of its cephalic appendix ; it is that of the CEstrus hcemorrhoidalis, which comes from the stomach and is expelled from the digestive tube to perform its metamorphosis. There is another larva, that of the Hippobosca equina, or horse-tick, better known under the name of flat fly, or spider-fly, because of its special form. These larvae are seen under the tail, on the sides of the anus, and on the genital organs, particularly in Oriental horses. They are flat, resistant to pressure, and very adherent to the above-mentioned parts. These flies sometimes emigrate to animals which are not accustomed to them, and excite the horses to such a state of agita- tion that they are suddenly seized with fright, run away, and demolish everything in their way. It is only necessary to remove the cause of this agitation as soon as it manifests itself, in order to avoid with certainty such formidable dangers. C. The Perineum and the Median Raphe'. The perineum is a single region comprised between the anus and the external genital organs. In the male it extends from the posterior part of the scrotum to just below the anus. Situated at first between the thighs, then between the buttocks, it is in relation anatomically to the corresponding part of the urethra and to the perineal aponeurosis which covers the latter. Its skin is black, or sometimes marbled, from the presence of leprous spots, which peculiarity should not be omitted in the description of the horse. It offers neither beauties nor defects for consideration ; it should be perfectly distinct and exempt from cicatrices, which might be the result of a dangerous operation, urethrotomy , practised in the treatment of calculus of the bladder, or the consequence of blow^s received by the animal. In the mare this region is much smaller ; it corresponds only to the narrow space situated between the vulva and the anus. Some authors have regarded it as extending to the mammae, whose situation is quite similar to that of the testicles. But even if we should observe this analogy, the study of the perineum, with regard to the exterior, would not gain in importance. As to the raphe, as its name indicates, it is a kind of cutaneous 176 THE EXTERIOR OF THE HORSE. thickening which marks the median line, from the sheath and the testicles, or the mammae, to the anus. It is shown in the form of a small crest, more or less prominent according to the subjects, 'is a simple peculiarity of the regions upon which it is observed, and, therefore, is devoid of all interest. CHAPTER VI. GENITAL ORGANS. THE examination of the genital organs should not be neglected, either for the purpose of ascertaining their good conformation in ani- mals which are destined for reproduction, or for simply proving their state of health or of disease. 1. GENITAL ORGANS OF THE MALE. These comprise, with respect to the exterior, the testicles and the penis, to which are annexed the protecting coverings, dependencies of the integument, known under the name of enveloping tunics for the former and sheath for the latter. A. The Testicles and their Enveloping Tunics. The organs which secrete the semen, the reproductive fluid of the male, are two glands, situated on each side of the median line, in the inguinal region, and between the thighs. They constitute, as a whole, an irregularly-rounded mass, divided in its middle into two almost equal lobes, by a slight groove, a sort of raph6, which behind is con- tinuous with the perinea! raphe, and in front is prolonged upon the inferior surface of the sheath. 1st. The Enveloping Tunics. The testicles are surrounded by several superposed envelopes, which are, proceeding from the superficial to the deep parts : a. The scrotum, or the skin (but the whole double sac, composed of all the enveloping tunics, is also spoken of as the scrotum). b. The dartos, very adherent to the latter, and forming for each testicle an independent musculo-elastic sac. c. The sub-dartoid connective tissue, a more or less dense layer, which separates the dartos from the following tunic. d. The cremaster or tunica erythro'ides, a striated muscle which is attached to GENITAL ORGANS. 177 the external surface of the fibrous tunic, and determines the rapid ascending movements of the testicle. e. The fibrous tunic, which surrounds the serous sac in which the testicle is suspended. /. Finally, the vaginal tunic or sheath, a diverticulum of the peritoneum, covering the inner face of the fibrous tunic and surrounding the testicle as well as its suspensory cord. The development of the testicular envelopes varies according to diverse circumstances, such as the degree of descent of the testicles, the state of health or of disease, rest or exercise, the temperature, the race, etc. Contrary to the general opinion, they are always formed at birth, at which time occurs the commencement of the descent of the testicles ; but they soon disappear, to reappear towards the end of the first year, following, consequently, the migration of the organs which they protect. These tunics, thin, soft, unctuous, and shiny in fine and well-nour- ished subjects, are thick, coarse, dull-colored, and rough in common horses. The scrotum or skin is, with few exceptions, almost hairless, of a black color, or only covered by some downy hairs. Nevertheless, in light-colored animals it is sometimes deprived of pigment in certain places, and then offers white or red spots of a variable area, to which is given the name leprous spots. 2d. The Testicles. Suspended at the extremity of a cord con- stituted by the vas deferens, blood-vessels, and nerves, these glands consist of ovoid masses depressed laterally, and related by their external face and superior border each to an elongated organ, the epididymis, enlarged at its two extremities and formed by an indefinite number of convolutions of its excretory canal. They float freely in their envelopes, but are neither in the same horizontal plane nor in the same transverse line : the left is always more inferior and more posterior than the right. The two testicles are, therefore, so disposed that they can approach the median line without being mutually compressed during the adduction of the thighs, between which they are situated. It is apparent how painful to the animal and dangerous to these organs such friction and compression would be if frequently repeated. The examination of the testicular region requires some precautions, particularly in irritable and sensitive horses. Let us suppose that this examination be practised upon the left testicle. The head is maintained in an elevated position by an assistant ; in addition, the anterior right foot may be raised. This being done, the 12 178 THE EXTERIOR OF THE HORSE. surgeon stations himself opposite the croup of the same side, places the left hand upon the dorse-lumbar region, being careful not to stand in the line of action of the corresponding posterior member, and goes, with the right hand, in search of the testicles, having previously caressed the parts which surround the region. When these organs are well developed, lie in the scrotum, and are consequently visible and tangible from the exterior, the horse is entire, 1 and is also called stallion; he is called gelding after emascu- lation. Emasculation is performed for various reasons, most usually with a view of completely destroying the function of these organs. The testicles, in the entire male, should be well down, rounded, almost equal, firm, and rolling under the pressure of the fingers, with- out showing any abnormal sensibility. They are larger in the adult animal than in the colt, and in Arabian, Barb, and Andalusian stallions than in those of other races. In hot weather they may become some- what flabby and pendulous. When they are small and retracted towards the inferior orifice of the inguinal canal, soft, or altogether pendulous, they indicate a horse that is degenerated, without energy, without vigor, and unsuited for reproduction. The gelding has the testicular envelopes flattened and almost indis- tinguishable from the posterior part of the sheath of the penis. There always exist on each side of the median line, at the place where the testicles have been, two linear cicatrices, slightly excavated, which present the same characters in all emasculated animals, and which are due to the excision of these glands. A horse may have been subjected to an operation destroying his reproductive faculties, and still have his testicles in the scrotum. This operation, known under the name bistournage, is nothing else than a subcutaneous torsion of the testicular cord, which is soon followed by a complete atrophy of the organ due to the obliteration of the blood- vessels which nourish the testicle. Although very little practised upon the horse at present, bistournage leaves traces which can be easily recognized : the volume of the tes- ticle is no more than that of a large walnut ; it occupies an elevated situation, and is no longer movable in its envelopes, in consequence of the adhesions which are established under the influence of the inflam- matory phenomena consequent upon the torsion. When the testicular envelopes present the characters recognized in the gelding, and ther*e exists on the surface no appreciable cicatrix ; 1 Technically, the word horse signifies the entire male. GENITAL ORGANS. 179 when, besides, the animal neighs frequently, has an erection of the penis at the approach of mares, and shows himself endowed, in appear- ance at least, with all the instincts and aptitudes of the most vigorous entire male, it is certain that he has not been castrated by bistournage, or otherwise, but that his testicles have not made their normal descent, and either float in the abdominal cavity or remain lodged in the ingui- nal canal. In either case the horse is called a cryptorchid l -or an enorchid. 2 Very often he is called an (worchid* but this is an improper designation, because it indicates the absence of the testicles instead of simply expressing their irregular situation. In ordinary language a cryptorchid is called a ridgeling. In scien- tific language we do not advocate the use of this expression, which originated from the horseman, but which is not confined to him, if we may judge from the favor which it has met among a certain class of individuals. Whatever terminology may be used, it is none the less true that that cryptorchism does not always exist on both sides at the same time. It is quite common to find it unilateral, but it is an error to believe it affects the right side oftener than the left. Since 1847 we have established the falsity of the foundation of this opinion ; it is useless to prolong our remarks on this question. Cryptorchids have always been regarded, with good reason, as being troublesome and dangerous to their companions as well as to their attendants. They often interfere with the manoeuvres of cavalry by kicking and biting, or unfasten themselves in the stable during the night, and mount the mares which they get access to. They are very ardent, and perform copulation readily, although this act appears to fatigue them extremely. We have not succeeded in getting them to repeat it on the same day. Finally, it should not be forgotten that these animals are sterile whenever the two testicles remain in the abdominal cavity ; their semen contains no spermatozoa. This secre- tion has the same characters in those animals in which the glands are arrested in the inguinal canal, as we have several times proved ; but we will not assert that it is always thus. The importance of the preceding facts is clearly demonstrated by the two following instances : One of them, given by H. Bouley, Jr., has reference to the remarkable Kivire- 1 From /cpvTTTw, 1 conceal, and 6p\is, testicle. 2 From ev, in, and op^is, testicle. 8 From inaire, annee 1886, p. 528; G. Chenier, contribution a 1'etude des actes locomoteurs, in Echo des soc. et assoc vtfir., Juin, 1866. 2 Such are : the flexors of the metacarpus, of the phalanges, of the forearm, of the metatarsus, the ischio t'bial muscle 5 :, etc. 8 Such are : the psoas, the superficial gluteus. the great dorsal, etc. 190 THE EXTERIOR OF THE HORSE. We are therefore convinced that during propulsion there is no antagonism of forces, but solely the use of the pOAvers intended to pro- duce an elongation of the members according to a definite plan. To become convinced of this, it will be necessary only to examine the muscles of one's own leg, semi-flexed, just before it becomes extended in order to straighten the body; all the structures are rigid because they all appear to contract in unison, so as to overcome the antagonistic forces. On the other hand, mechanical dispositions of great power and the arrangements of the muscles and tendons in the hind limbs of the horse associate the articular angles in such a manner that one of them oannot be extended without producing a simultaneous opening of the others. It follows from this that all the forces which are exerted at one point are transmitted at the same time to the adjoining parts and 52 . Anatomy, through the researches of Vincent and Goiffon 1 upon the cadaver, has determined the extent of this space, AB, in a very satisfactory manner ; but it becomes a difficult problem when it is a question of the precise location of the angle A OB in relation with the vertical line OX, or, what amounts to the same thing, to fix the limited positions A and B, points which indicate the limit of the oscillation of OC in the living animal. It is in this direction that investigations should now be pursued. It is possible, indeed, that if we could recognize the exact position of these limits in horses of speed, it would become easy to determine the most desirable inclination of the bony levers. Evidently this inclina- tion should assume the direction OC, bisecting the angle AOB. In this case alone the space of oscillation will reach its greatest possible limits for the extremity C, being equivalent from A and B, admits of equal flexion and extension, the greatest of each that is possible. All other inclinations diminish the one or the other of these movements. We have presented the only accessible observations that have been made on this subject, excepting only the incomparably accurate re- searches which MM. Marey and Pages 2 have undertaken with the aid of instantaneous photographs of horses in locomotion. 1 Vincent et Goiffon, Memoire artificielle des principes relatifs a la fidele representation des animaux, t. ii., Paris, 1779. 2 Pages, Analyse cinthnatique de la locomotion du cheval, in Comptes-Rendus de 1'Acade- mie des sciences, 1885, p. 702 ; Marey et Pages, Analyse cinematique des allures du cheval, in Comptes-Rendus, 1886 ; ibid., Mouvements du membre pelvien chez 1'homme, 1'elephant et le cheval, in Comptes-Rendus, 1887. 192 THE EXTERIOR OF THE HORSE, Unfortunately, these experiments have only determined the limited positions in the walk, the trot, and the slow gallop, and leave us still ignorant of what these positions are in extreme speed. Nevertheless, from the facts already acquired, an important proposition can be deduced : that the limit of extension of the locomotory segments occupies, in horses of speed y a point. A, quite close to a vertical line passing through their centre of movement. According to the angles considered, this point is situated either in advance of the vertical line mentioned (angles with the sine posterior), or behind it (angles with the sine anterior). But it is apparent that the farther the limit of extension passes beyond the vertical line of the centre of movement the more will the angle of these segments, when it is opened, be favorable to the augmentation of the obliquity of the member, and consequently the more will it tend to increase the ampli- tude of the step or the extent of the movement. It would follow from this that the most favorable inclination of an osseous lever is that which removes it the least from the vertical line OX during flexion, and consequently that which tends to approach it to this same line while the animal is standing still. In this case the direction of the segment will be more closely related to the bisecting line 0(7, which is associated, as we have seen, with the largest space of oscillation. In the preceding statements we have viewed an isolated locomotory segment, as it is moved freely under the horizontal line MN, without the intervention of foreign influences. This has permitted us to indi- cate to the best advantage the direction of the segment associated with a large and effective oscillation. In natural conditions, however, this arrangement is not so simple, since the locomotory angles are formed by bones which are articulated in twos or in threes. It is therefore in place to inquire whether, under these circumstances, the extreme limits A and B remain always the same with relation to the vertical line OX through the centre movement. It is easy to assure ourselves of the contrary. These positions de- pend upon the inclination of the segment with which the one under con- sideration is articulated. The maximum value of the articular angle may be similar, and, for the sake of the argument, we may say equal ; but the orientation of this angle being different, the extreme positions A and B are displaced either forward or backward of the vertical line, according to the obliquity of the adjacent segment. This will neces- sarily result in differences in the utilization of the articular movements in forward locomotion. THE MEMBERS. 193 FIG. 53. Let us suppose the two segments OC and OC / to have different obliquities when compared with the vertical line OX (Fig. 53). Let, on the other hand, COB' be the maximum extension of the angle COB. The angles, in extension, being equal, for anatomical reasons, to the segment OC', the limit of extension of OB will be B". A simple in- spection, however, shows that OB", being less inclined upon OX than OB', will also be less favorably di- rected than OB' in relation with the vertical line OX. Therefore, the orientation 01), bisecting the angle COB, is more favorable than the orientation OD' bisecting the angle C'OB. It can only be alleged that the angle C'OB, since it is more open while the horse is standing still, should be the same in action, but if it were thus the conditions would no more be equal, and consequently no more comparable. The condition of the maximum opening of the angle C'OB changing, it can be assumed that in the same manner the angle COB is caused to vary. Moreover, anatomy teaches that there exists for these two angles a maximum separation, practically the same, but dependent upon the disposition of the articular surfaces and the liga- ments limiting their displacement. The sole difference which distinguishes them is that in repose their branches are unequally inclined. Mode of Evolution of the Members during Progression. The mode of evolution or oscillation of the members during progression involves quite a complex analysis, but we must be able to explain its general features in order to understand some subsequent phenomena. Let us examine this oscillation in the walk, a mode of progress in which the body is never entirely disconnected from the ground. The foot, now elevated from the ground and now in contact with it, passes through two principal phases : one of elevation, 1 during which it is in the air, and one of contact, during which it supports a portion of the weight of the body. During this evolution, the line of direction of the member appears to oscillate alternately around two points situated at its superior and its inferior extremities ; the foot, the inferior extremity, is the point of the phase of contact ; the supe- rior, the centre of movement of the shoulder or the croup, is that of 1 The reader must have a clear conception of the meaning of the terms elevation and contact, because they are frequently employed in the following chapters. 13 194 THE EXTERIOR OF THE HORSE. the phase of elevation. When the first is stationary on the ground, the second, or superior point, describes an arc of a circle and is carried forward by the force of impulsion, and vice versa. At the moment when the foot, D (Fig. 54), is ready to leave the ground, the line of direction, H'D, is inclined downward and back- FIG. 54. Schemes of the evolution of two congeneric members during the phases of contact and of elevation. ward. It is then advanced, describing an arc of a circle, and when it reaches the point D' ', where it again touches its support, the line of direction, H"D, is reversed. In the same half of the body (anterior or posterior) the phase, DD f , of elevation of one member coincides always exactly with the phase of contact, UHJ" of the other. The successive positions of one member, whatever they be, are therefore directly the reverse of those of its congener. As to the relative velocities of the transmis- sion of the body and of the feet, they are different, but always in simple relation. The foot, in the same space of time, passes over a distance, DD', double that of the centre movement H'H". Its velocity is therefore twice as great. Many years ago Captain Raabe 1 and M. Colin schematically rep- resented the oscillations of the extremities in the following manner : Let us suppose that we examine the evolution of the posterior pair of limbs. The centre of the croup, If, during the phase of contact, describes a uniform movement in advance which carries it from H to H', it being supported by the right posterior limb, D. At this instant H', the right leg, is elevated, H'D, and 1 Raabe, Examen du Trait6 de 1'exterieur du cheval, de Lecoq, et de la Physiologic, comparee, de M. Colin, Paris, 1857. See, besides, the plates in the Traite de Physiologic, de M. Colin, t. i. p. 445, 3e ed., Paris, 1886. THE MEMBERS. 195 the posterior left, G, on the contrary, goes to rest on the ground, H'G, at a distance, DG, equal to a half-step. While the latter, G, passes through its phase of contact, the centre of the croup passes through the space from H' to H" and describes the arc H'H" equal to that described by the right, because, in the normal gait, the steps are equal. Arrived at If", the left member, G, becomes elevated, H"G ; the right, on the other hand, is now placed on the ground, H"D', to renew its phase of contact at a distance, GD / , equal again to a half-step. During its progression, the right foot, therefore, proceeds from its initial po- sition D to attain its final position D / . It consequently passes through the arc Diy, while the centre of the croup only passes over the space H'H", which is exactly one-half of the distance DD' '. H'H" is parallel to DD', for the isosceles triangles GH'D and GH"D' are equal, since GD and GD' are equal. Again, the analogous angles GDH' and D'GH" being equal, the lines DH' and GH" are parallel. Therefore, H'H" = DG = ^-> When one of the members has passed successively through the two phases of contact and of elevation, the body effects what is called a complete step, the two pairs of members (anterior and posterior) being jointly concerned. During this evolution it can be seen that the centre of movement, H, and consequently the centre of gravity, has progressed from Hto H", or, what is equivalent, through a space which is equal to the line DD', equal to the distance passed over by one of the feet, a distance completed in two attitudes, HD, H"D', identical and successive. It follows from these statements that the length of the step will be measured by the separation of DD', comprised between the successive imprints left upon the ground surface by the same foot. But for an accurate analysis (such as is often necessary) the division of the step into the two principal phases of contact and elevation, above mentioned, is insufficient. It is necessary to subdivide each into a number of equal secondary divisions called periods. All veterinary writers, with Captain Raabe, recognize at present the following six periods (see Fig. 55) : f 1st period, from to 1 ... Commencement of the contact. Phase of contact, -j 2d period, from 1 to 2 ... Middle of the contact. (. 3d period, from 2 to 3 ... Termination of the contact. Phase of elevation ( 4th peri d ' fr m 3 to 4 Li f tin 9 of the foot. or of extension. ] ^ peri d ' fr m 4 tO 5 ' ' ' Mddle f elevation ' V. 6th period, from 5 to 6 ... Resting of the foot. Systematic Analysis of the Play of the Members. The general scheme of the evolution of the members, which we have given, has permitted us to prove a certain number of facts, and to 196 THE EXTERIOR OF THE HORSE. formulate these into intelligible propositions. As a whole, the conclu- sions which have been deduced are exact ; but if we endeavor to make a more minute analysis of these phenomena we shall find that they are not so easily worked out. Strictly speaking, the limb of a horse cannot be compared to a long lever which alternates by turns round its inferior extremity when the latter is related to the surface of support, or its superior when it is lifted. In other words, the displacements of the leg are not assimilable to those of an oscillating pendulum, as Captain Raabe and his disciples have supposed. 1 They result from a series of partial movements which influence each other mutually and give to the articular centres very complicated trajectories. The recognition of these secondary actions offers interest from a point of view of the particular mechanical role fulfilled by each region. It is necessary to make some remarks con- cerning this statement. MM. Marey and Pages, 2 in their recent and valuable researches with the aid of chrono-photography (see Generalities upon the Gaits), have been enabled to register the successive positions of the different bony segments of locomotion and the relative duration of their revo- lution during the execution of the two principal phases of contact and of elevation of a complete step. Let us see what interpretations can be given to the phenomena indicated by these original investigations. Take, for example, the movements of the members in the ordinary trot ; like MM. Marey and Pages, we will choose, among the numerous positions aifected by these apparatus, a certain number of attitudes well characterized by the extension and flexion of some segments, or by important modifications of the articular trajectories. i. Action of the Anterior Member (Fig. 55). A. Phase of Contact. The anterior member (which during this phase arrives at a state of rest in an attitude of extension w r hose degree varies with the extent of the pace and the nature of the gait) should successively fulfil two very distinct roles, of which the purposes are, first, to deaden the shock of concussion against the soil, and next, to extend itself. After this process is over, it again prepares to elevate itself. 1 These views have been demonstrated in a recent work entitled L'art e"questre, par M. Barroil, p. 21 et suiv., Paris, 1887. Chez Rothschild. 1 Marey et Pagds, Analyse cinmatique des allures du cheval, in Comptes-Rendus de 1'Acade- mie des sciences, 27 Septembre, 1886; ibid., Mouvement du membre pelvieu chez 1'homme, 1'elephant et le cheval, in Comptes-Rendus, 18 Juillet, 1887. THE MEMBERS. 197 1. Attenuation of Concussion. This is effected during the movement from to 2 by the diminution of the two extreme angles (the scapulo-humeral and metacarpo-phalangeal) placed at the extremi- ties of the rigid radio-metacarpal segment. The fetlock is strongly nip FIG. 55. Action of the anterior member in the trot. A. Phase of contact. | S. Phase of elevation. lowered and the radio-metacarpal segment pivots forward upon the pastern, which is horizontal and immobile. During the second period, from 1 to 2, the closure of the scapulo-humeral angle is most marked. 2. Extension of the Member. Extension takes place in a progressive manner from 2 to 3 (Fig. 55). The line of direction of the member becomes vertical, elongated, and at the termination is directed downward and backward. The angle of the fetlock and that of the elbow are opened : the first by the gradual straightening of the pastern, which pivots on the coronet and becomes vertical ; the second by the forward rotation of the radio-metacarpal division, which pivots upon the first phalanx. As to the angle of the shoulder, it becomes slightly augmented by the forward rotation of the scapula. It is now observed that during this period the member can fulfil a function of impulsion, particularly when the resistance to progression is considera- ble, as in strong traction, for example. Preparation for Elevation. Elevation is manifested during the movement from 3 to 4 (Fig. 55). The pastern continues to rotate in advance, carrying with it the foot, which pivots upon its toe. The radio-metacarpal angle becomes slightly flex'ed, while that of the shoulder continues to augment. At the moment of elevation nearly all the articular angles have reached their maximum extension. S. Phase of Elevation. During this phase the foot leaves the 198 THE EXTERIOR OF THE HORSE. ground, is carried forward, and finally establishes a new point of contact. Directed obliquely downward and backward at the beginning, the member is directed in an inverse sense at the termination. It therefore successively becomes shortened, elongated, and finally assumes a new point of contact. 1. The shortening manifests itself more particularly during the motion from to 2 (Fig. 55). It is characterized at first by the maxi- mum flexion of the pastern producing a closure of the angle of the fetlock, of the canon, and of the forearm, resulting in a diminution of the angle of the carpus and of the elbow. Arrived at the point 2, the angle of the fetlock already begins to open in consequence of the straightening of the pastern. As to the shoulder, it contributes, by its backward rotation, in the shortening of the limb and in closing the scapulo-humeral angle, though only to a small degree. The diminution of the length of the member is therefore progressive, and passes from below upward by a greater and greater flexion of the articular angles. 2. The elongation, which commences at 2 (Fig. 55) by the exten- sion of the fetlock, is continued to 3 by that of the metacarpus, by the opening of the angle of the elbow, and, finally, by that of the shoulder. These phenomena are not all simultaneous. They are due to a gradual and successive extension of the pastern, the canon, and the arm, and the lengthening of the inferior extremity of the member commences before the shortening of its superior part has reached its maximum. The preparation to touch the surface carries the anterior mem- ber to its limit of extension. The radio-metacarpal angle is effaced ; those of the elbow and the shoulder now attain their maximum sepa- ration. As to the pastern, it extends obliquely downward and forward ; the foot is resting in the same axis. 2. Action of the Posterior Member (Fig. 56). The posterior member, being an agent of attenuation, impulsion, and ambulation, offers attitudes analogous to those of the anterior. A. Phase of Contact. Like its homologue, this member arrives in station in a state of extension whose degree varies with the length of the pace and the nature of the gait. During this phase it also deadens the concussion against the ground and develops the force of impulsion ; having accomplished these, it again prepares for a position of station. 1. The attenuation of the concussion is effected from to 2 by THE MEMBERS. 199 the descent of the fetlock and the closing of the coxo-femoral and the femoro-tibial angles. These articular phenomena are due : to a sudden horizontal direction of the pastern, which pivots upon the os corona, produces a lowering FIG. 56. Action of the posterior member in the trot. A. Phase of contact. | S. Phase of elevation. of the fetlock, and straightens the canon ; to the forward rotation of the tibia upon the tarsus, which lowers the femoro-tibial articulation ; finally, to a greater obliquity of the femur, which results in a lowering of the coxo-femoral angle. 2. The development of the impulsive force is effected principally from 2 to 4 (Fig. 56), during which movement the foot is on the ground. In this space the line of direction of the member becomes directed obliquely downward and backward, and the latter becomes elongated progressively by the almost simultaneous opening of all its angles. This takes place first at the pastern, which rotates forward upon the os corona, becomes vertical, and opens the angle of the fetlock ; the canon is now extended and opens the angle of the tarsus; finally, the superior extremity of the tibia is directed more obliquely forward, and the inferior extremity of the femur is carried backward, thus opening the angles of the femoro-tibial and the coxo- femoral articulations. The preparation for elevation succeeds the period of impul- sion and manifests itself at 4 (Fig. 56) ; the hoof and the pastern pivot in advance upon the toe, whence a slight flexion of the fetlock : the canon is now rotated backward at its superior extremity, and the movement also produces a feeble closure of the tibio-metatarsal angle. 200 THE EXTERIOR OF THE HORSE. S. Phase of Elevation. In these phenomena the foot leaves the soil, oscillates forward, and then assumes a point of contact. The line of direction of the member is first inclined backward, and after- wards obliquely forward. The posterior column, like the anterior, should successively become shortened, elongated, and prepare itself for station. 1 . Shortening. This process presents the following stages : a. Maximum flexion of the pastern and slight flexion of the canon and the thigh, producing a marked elevation of the foot and a maximum flexion of the fetlock, which, however, is only feeble in the hock, the stifle, and the hip (0 to 1). b. Very marked flexion of the canon and the femur, with an accentuated closing of all the articular angles except that of the fetlock, which commences to open itself by the extension of the phalanges (1 to 2). 2. Elongation of the Member. The elongation commences by the extension of the fetlock, to be continued by that of the hock and the stifle from the sole influence of the extension of the tibia on the tarsus (2 to 4). The coxo-femoral angle has now reached its minimum size. Before the foot again reaches its point of contact, the angles of the stifle, the hock, and the fetlock have reached their limit of extension almost entirely under the influence of that of the leg, which itself has attained this limit of movement. The pastern, which now tends to become horizontal (4) again, thus carries the hoof far. in advance. All these are conditions of structure more or less closely allied to the production of force or speed, and these we shall examine in the pages that follow. We shall also demonstrate that the animal motors can be submitted with the greatest accuracy to the same scientific analy- ses, according to mechanical principles, as the inanimate motors which are the production of human ingenuity. CHAPTER I. ANTERIOR MEMBER. THE anterior member comprises several regions which we describe in the following order : the shoulder, the arm, the forearm, the elbow, the knee, the canon, the fetlock, the footlock, the ergot, the pastern, the coronet, and the foot. ANTERIOR MEMBER. 201 A. The Shoulder. Several authors have intentionally united the description of the shoulder with that of the arm, because of the fact that, in relation with the exterior, there exists between them no definite line of separa- tion, and that, in relation with their functions, they are intimately united. There is, nevertheless, no more reason for con founding these regions than there is for uniting the croup with the thigh, the back with the loins, or the neck with the head. We shall therefore study them separately. Situation; Limits; Anatomical Base. Situated between the neck and the sides of the thorax, the withers and the arm, the shoulder occupies, without any precise demarcation, the lateral and anterior region of the chest. The scapula is flat and triangular, and is provided with a strong spine on its external surface and a wide cartilage of prolongation at its superior border. It thus forms the osseous base of the shoulder, and gives attachment to two kinds of muscles, which, with respect to the anterior member, can be distinguished as extrinsic and intrinsic. Besides, this bone participates by its inferior extremity in the formation of an articulation very mobile and at the centre of the move- ments of the arm. The extrinsic muscles originate from the vertebrae, the ribs, and the sternum. Viewed only as to their action upon the shoulder, their function is to fix the latter to the trunk and regulate its displacements. The intrinsic muscles embrace and sustain the scapulo-humeral arthrodia, and act exclusively upon the arm, except three which extend to the forearm (the long and short flexors and the great extensor of the forearm). These intrinsic muscles determine most of the movements of the humerus, and carry this bone into extension, flexion, abduction, and adduction. They also oppose the closing of the articular angle during station, and maintain in proper relation the two bones which form it. Form. It is difficult to assign a geometrical form to the shoulder on account of its intimate connections with the thorax, the neck, the withers, and the arm. In lean subjects, the most salient parts of its conformation are very markedly delineated underneath the skin : in front, its anterior border projects from the base of the neck ; above, its cartilage is indicated by a curve parallel with the superior line of the withers ; on its external face a longitudinal crest, formed by the acro- mion spine, extends from above to below ; behind, a less marked furrow separates it from the thorax ; in front and below, a round, voluminous eminence, improperly called the point of the shoulder, 1 1 It is formed, in fact, by the superior extremity of the humerus, and merits much more appropriately the name point of the arm, under which Bourgelat described it. 202 THE EXTERIOR OF THE HORSE. forms the summit of the scapulo-humeral angle and indicates externally the origin of the region of the arm ; finally, immediately behind this angle, and upon the external surface of the great extensor of the fore- arm, is found what is termed the blemish of the shoulder. An ordinance of sanitary police, of the 31st of August, 1842, prescribed that all horses suspected of suffering from contagious diseases should be marked in this region by a square brand. In fat and well-muscled horses these prominences of the shoulder are almost completely effaced ; the external face, the anterior border, and the articulation become rounded and insensibly confounded with the adjoining regions ; the form of the shoulder must be surmised rather than perceived, unless it is revealed while the animal is exer- cised at a more or less rapid gait, in which event its movements will inform us as to its general form, its dimensions, and its direction. Movements. When, during the walk, the anterior member leaves its point of contact with the ground, it becomes shortened, directed forward, and all the articular angles close themselves by the flexion of the segments which form them, and the foot is elevated a certain distance above the soil. But if the shortening were manifested only in a vertical direction, it is easy to understand that the foot would arrive at precisely the same point which it previously occupied without, of course, communicating any propulsion to the trunk. In order to give amplitude * to the step, it is indispensable there- fore that the bones be carried forward, and that the displacements begin at the superior extremity of the limb (the scapula) and terminate with the foot, one piece being moved upon the other. The shoulder is the region whence proceed the initial movements when the member is advanced. In this phenomenon the shoulder is slightly elevated by means of the surrounding muscles ; its humeral angle rotates forward while its superior border is carried downward and backward, and the extent of this movement is directly proportional to the length of the muscles which produce it. The elevation of the humeral angle is effected principally, through its con- nection with the humerus, by the strong mastoido-humeralis muscle which ex- pands over the anterior surface of the articulation. It is aided in this action by 1 We designate under this name the linear displacement of the inferior extremity of the member in advance of its vertical axis, the result of the successive movements of the angles and bones which compose it. This displacement is equal to one-half of the oscillation of the motor column, which is, metaphorically speaking, not unlike a body swinging to and fro in the man- ner of an articulated pendulum, but with this difference, that here the muscular contraction replaces the weight which alone causes the latter to oscillate. ANTERIOR MEMBER** 203 the sterno-humeralis, directed obliquely outward, downward, and backward; finally must be added the serratus magnus, which draws the dorsal angle of the scapula downward and backward, as well as the dorsal trapezius. As soon as the member has completed its extension the elevation of its supe- rior border, and consequently the lowering of the articular angle, is effected by the trapezius, the rhomboideus (the proper elevator), and the angularis on the one part, and the sterno-trochineus and the sterno-prescapularis on the other, and the member is again brought into its primitive position. These two movements, intimately associated, are executed actively by the muscles above named, and passively by the weight of the body. The scapular play, it is needless to say, should be as easy, supple, and extensive as possible. Nevertheless, there are some horses whose shoulders, though regularly constructed, are unable to rotate with sufficient freedom, and this limitation markedly restricts the move- ments of the member. Such a shoulder is vulgarly called pegged. (See Defects of the Gaits.) Length. The most important phenomenon in the construction of the shoulder is its length, or, in other words, its development from the summit of the withers to its point. Two factors enter into the production of this dimension : the height of the spinous processes of the first dorsal vertebra above the scapular cartilage, and the length of the shoulder properly so called. But as the variations of one of the elements of this region are not always correlative with those of the other, it follows that the real length of the shoulder is not strictly given by the distance from the summit of the withers to the point of the arm. This restriction being established, let us view the assigned limits of this length and the advantages which follow its marked development. Bourgelat was the first one to mention that the distance comprised between the summit of the head and the commissure of the lips equals almost exactly the measurement of the shoulder from the withers to the insertion of the neck on the breast. 1 This is an observa- tion which is quite accurate, as has been testified by some of the very best authorities on such subjects, notwithstanding the active opposition which it has received from the generality of hippotomists. Those who, like ourselves, have taken the pains to verify by numerous measure- ments the exactness of this fact, Colonel Duhousset among them, have somewhat modified it by saying that the entire length of the head equals the distance from the summit of the withers to the point of the" shoulder. It is thus, at least, in the more beautiful and perfect * C. Bourgelat, loe. cit., p. 204. 204 THE EXTERIOR OF THE HORSE. horses, whatever may be the service to which their conformation adapts them. The exceptions are much less numerous than is gen- erally believed. Nevertheless, such variations, although not very marked, do exist, and the expe- rienced eye will recognize a shoulder that is long or one that is short (Fig. 57). The length of the shoulder, in order to appreciate it accu- rately, should be viewed : (1) in the absolute; (2) in relation to the arm. 1. Absolute Length of the Shoulder. It is neces- sary, for various reasons, that the shoulder should be as long as possible. First, its length necessi- tates a correlative development of the intrinsic muscles, the ex- tent of whose contraction is directly proportional to the movements effected by the hu- merus. Secondly, the degree of am- plitude of the rotation of the scapula in relation with the movements of the member as a whole, and the arc described by each extremity of this bone and taking place around a defi- nite centre, are more extensive as the length of this region in- creases. The value of high FIG. 57. withers lies in the length of its muscles, for long shoulder-muscles correspondingly augment this scapu- lar movement. Thirdly, besides being in relation with the vertical diameter of the chest, an ample length of the muscles has a disposition to render the shoulder more oblique, another beauty whose value in horses pos- sessed of speed we will presently explain. A long shoulder, as it is ANTERIOR MEMBER. 205 applied vertically or obliquely upon the sides of the thorax, has a tendency of itself to elevate or to lower the centre of gravity by augmenting or by diminishing the total length of the member in this proportion, at those times when the anterior extremity of the body is 'being displaced. The centre of gravity, however, in order to be in accordance with the laws of equilibrium and of speed, should have a favorable position and not be too elevated. Furthermore, a shoulder can profit by its length only when it is correspondingly inclined ; otherwise, the reactions will be hard and the animal without action in consequence of the defective orientation of the superior angles of the member. There is an idea, very generally prevalent, that, in the draught- horse, marked length of the shoulder constitutes a defect rather than an advantage. This is an error which the partisans of such a theory could very easily demonstrate by making some practical measurements upon the very best specimens of draught-horses. In them, also, the head is the measurement of the shoulder. The great length of this region is in all cases, in our opinion, the first and most important ele- ment of its beauty and perfection. There are, without doubt, draught- horses with short shoulders capable, nevertheless, of very effective service, and the disadvantages of this defect in them do not have the same importance which they would have in the race-horse. In the draught-horse, amplitude of the movements is secondary ; the essen- tial qualities reside in the resistance which can be overcome by the power of his muscles and the proper incidence of their insertions. To say that the length of the scapula and its muscles, in these slow- moving animals, is defective and incompatible with the power of the muscles, is to advance a principle which is entirely incorrect and with- out proof. 2. Length of the Shoulder in Relation with the Arm. On general principles the shoulder and the arm should be long abso- lutely, in order to be favorable to velocity ; but, with the same total length of these two segments, it is necessary that the former be long and the latter short. This becomes apparent from the following dem- onstration : Let us represent (Fig. 58) the two shoulders, AB, AB / , and the two arms, CD, CD', having the same reciprocal inclination and giving the same total sum, AB+ CD being equal to AB'+ C'D' by hypothesis. AC 1 From our estimations, the relation - is equal to - ; we have preserved the AD o A C / same relation for - -, the conditions in both cases being therefore comparable. AD 206 THE EXTERIOR OF THE HORSE. Let us suppose now that the extensors of CD and those of C'D' are shortened through the same space ( CE = C'F\ a phenomenon which, however, in reality does not occur, since the muscles are of differ- ent lengths. The arm CD will be carried to EG, while C'D' will be displaced to FH. Whence it follows that the point D will reach a situation more advanced, G, in relation with the limit of extension, than the point D', which will de- scribe the arc D' H always smaller than the arc DO under the special proposi- tion with which we started. (if equalling^)- The angular dis- placement of the short arm, CD, is therefore more extensive for an equal contraction or shortening of the mus- cles than that of the long arm, C'D'. In addition, the ex- tensors of the shoulder AB are longer than F IG . 58. those of the shoulder AB'. Consequently, the muscles of the latter are obliged to shorten themselves more for the production of the displacement DG, which the extensors of AB will effect without fatigue. Finally, as the effort of a muscle varies according to certain condi- tions, among others with the resistance to be displaced, it follows that the shoulder AB will produce the extension of the arm CD more easily than AB' that of the arm C"D', since the former is shorter and consequently less heavy than the latter. Thus the length of the shoulder in comparison with that of the arm should be as great as possible, for the reason that it effects a greater displacement of the^humerus with a more feeble muscular con- traction. ANTERIOR MEMBER. 207 Direction. Another element in the beauty of the shoulder of the race-horse in particular resides in its obliquity. This direction is indicated by an imaginary line which passes from the summit of the withers through the centre of the scapulo- humeral articulation. Observation has demonstrated that this line passes a little posterior to the scapular spine. Marked obliquity of the shoulder has always been considered a beauty, or point of excellence, in close relation with the production of speed ; while in its relation with the development of force it is com- paratively indiiferent. Nothing is more easy of comprehension. Let us represent (Fig. 59) OA and OA / , two shoulders of unequal obliq- uities, and OS, the humerus on which they operate. Let us suppose, also, that A OB' be the maximum opening of the angle AOB. All things being equal, the limit of extension of the humerus on the shoul- der OA' will be carried to B", since, from the anatomical union of the two regions, the angle A / OB" is equal to the angle A OB'. (See Generalities on the Mem- bers, p. 194.) OB" being more distant from the vertical line than OB', will also be relation with the vertical direction OX. FIG. 59. favorably directed than OB' in The orientation of the scapulo-humeral angle is therefore most favorable to progression when the shoulder is oblique; the inferior segments of the member are further advanced, and such a shoulder especially if it be long will be capable of producing a much more extensive revolution of the humerus BB f . If, instead of becoming larger from the straightening of the shoulder, the scapulo-humeral angle remains the same (A' OC= AOB\ it is correct to assume that, from an equal functional shortening of the muscles, the humerus O C will be carried less in advance than the humerus OB. Such are the reasons which operate in favor of a great obliquity in horses of speed ; but this is not all. If we study the movements of the shoulder, viewed separately, the fact becomes evident that, for an equal elevation of its extremity, it will 208 THE EXTERIOR OF THE HORSE. be carried much more in advance when it is inclined than when it is straight. Let us represent by AB and A / B / (Fig. 60) these two different directions ; by BM and / M / two vertical lines drawn from the superior extremity of each FIG. shoulder; finally, by ACandA'C', equal amplitudes of the two scapular oscilla- tions. It is assumed, by hypothesis, that AM^> A'M'. Whence it follows that A M + ACis> A'M' + A / C', or, in other words, that MC is > M' C'. Therefore, for an equal arc described by the point of each shoulder, the more inclined will carry the lower or distal extremity to a position the more anterior. This will also allow a greater extension of the humerus, and the forearm will reach for- ward to a point more in advance. It is certain, a priori, that a straight shoulder is capable of a greater oscillation forward, but it must be remembered that the degree of the scapular movements is the result of the functional shortening of the ele- vator muscles of the point of the arm. This shortening alone gives the measure of rotation, a measure which we know is proportional to the muscular length. We have sufficiently dwelt on this particular point cl propos to the neck without again making reference to it here. Another advantage of an oblique shoulder lies in the perpendicular incidence of the muscular jnsertions (Fig. 61). FIG. 61. ANTERIOR MEMBER. 209 The line AE, which indicates the direction of the elevators of the shoulder AB, is more perpendicular to this segment, and consequently more powerful than is its homologue CE, which is attached to the shoulder CD. But it can be seen that the mechanical inconveniences resulting from the latter conformation will be mitigated to a certain degree by a more horizontal direction of the neck EF. It is also ob- served that horses with straight shoulders, and which have to_employ great force, carry their necks very low, so as to increase the power of the muscles by giving them the best incidence, and to enable the centre of gravity to be more easily displaced forward. The Scapulo-humeral Angle. The obliquity of the shoul- der, an element to be desired for velocity, tends to effect a reduction of the dimension of the scapulo-humeral angle. This circumstance would, consequently, restrain the extent of play of the latter, if the humerus, by a more vertical position, did not preserve a normal separa- tion of these two' segments. Whatever may be the value of this direction of the humerus, it never attains such a degree as to give to this angle the same obtuseness which the other angles of locomotion have, excepting the coxo-femoral. Normally, in running- and trotting-horses, the scapulo-humeral angle is much more acute than any of the others. The consideration of this fact alone is, however, not suffi- cient to establish our position. It is necessary that the arm itself have good direction ; in a word, that the angle remain well situated in relation to the vertical axis of the member. Our measurements have shown us, in fact (Fig. 62), the angles AOD and AOCy as well as the angles BOD and BOG. It may be said that a large scapulo- humeral angle can coexist with an oblique shoulder, and, vice versa, a small one with a straight shoulder. It can be understood by this time why so many beautiful or ideally per- fect shoulders fail to fulfil the expec- tations which are based upon them, and how, also, the inclination of the arm constitutes, to a certain point, a compensation for a straight shoulder. In the latter case, the animal may still bo capable of great 14 210 THE EXTERIOR OF THE HORSE. speed, but he does not receive the benefits which should result from the fixation of the scapulo-humeral angle in advance. Whenever the anterior member is advanced, the point of the shoulder is not suffi- ciently elevated to permit the other segments to attain their maximum degree of movement. As a natural consequence of this, the gait is deficient, the feet are but little elevated from the ground, the steps are short, and the movements rapid. The scapulo-humeral angle in horses of the best conformation is not 90 degrees (as is generally but incorrectly supposed) ; and, a fortiori, the inclination upon the horizon of the two segments constituting it is more than 45 degrees. In the articular angles, the axes of move- ment of the branches should meet in the probable centre of the articu- lation. The central point of the scapulo-humeral union is not, as has been commonly believed, the point of the arm (the summit of the trochiter and trochin). Its situation is more posterior, and corresponds externally to the convexity of the great trochanter over which the tendon of the sub-spinatus muscle glides. It is at this point that the axes of the scapula and the humerus meet, and the angle formed by these lines can be measured in the living animal when the bones are placed in their normal position in relation with the median line. Our measurements have given us 55 degrees as a mean inclination of the scapula in horses possessed of speed, and 65 to 70 degrees in those used for slow and heavy work. The beautiful models of rapid draugh1>horses do not differ sensibly, in this relation, from the champion of the race-course, and we do not hesitate to affirm this fact in opposi- tion to those obstinate partisans of the oblique shoulder, who value it only in the race-horse, and declare it a defect in the draught-horse. The unpublished observations on this topic which Professor Laulani6 has kindly communicated to us, although less numerous than ours, fully corroborate our own. According to our distinguished colleague, the mean scapular inclination is 57 degrees, the extreme measurements varying from 50 to 66 degrees. The scapulo-humeral angle has been determined by us to have a mean dimension of 115 degrees, and we have seen it vary from 110 to 130 degrees in all types of horses. Resume. It results from the preceding statements that the direc- tion of the shoulder is in intimate relation with the speed. It is desirable to have it as much inclined as possible, because its obliquity will admit of a greater extension of the humerus ; it will permit the member to be raised higher and to complete the extension before placing the foot on the soil ; it will more strongly project the foot, and will be ANTERIOR MEMBER. 211 compatible with a favorable orientation of the scapulo-humeral angle ; finally, it will give suppleness, style, and amplitude to the gait, and at the same time will attenuate those reactions whose effects are as injurious to the rider as to the horse himself. Scapular obliquity usually accom- panies elevated withers and great depth of thorax. It gives to the horse a mark of distinction which denotes the nobleness of his race. All other directions of the shoulder are antagonistic to velocity from the fact that their elements are diametrically opposite to those of the conformation we have described. These disadvantages, however, disappear, as before stated, in slow and heavy work for which force alone is required. To conclude, from these remarks, that the shoulder of a heavy Per- cheron is defective because it is not straight, would be wrong; and those who will endeavor to prove it by real measurements will recog- nize that, in the very best specimens of this class, this region, neverthe- less, will show a marked inclination. Without doubt, in such cases, the most beautiful and perfect shoulder is that which offers the greatest surface for the adaptation of the collar. It is a serious mistake to suppose that an inclined scapula does not furnish the elements of this large surface, for it excludes nothing favorable to muscular power. It has also been said that, in the presence of such a shoulder, the application of the collar is against the scapulo-humeral articulation only ; whence a certain amount of pain during the efforts of extreme traction, bruises of the sensitive parts, wounds, etc. These are objec- tions which have value only when the shoulder is too sharp, emaciated, or poorly muscled, and consequently leaves the articulation too much in relief; but if it become defective for this reason alone, the defects must not be attributed to the obliquity. If the muscles be well developed this hinderance will disappear, especially if the precaution be taken to elevate the attachment of the traces. It seems useless to repeat so often the aphorism, the harness is made for the horse, and not the horse for the harness. Nevertheless, how few harness-makers seem to appreciate this fact, but prefer to choose the collar without taking the measurement of the shoulders ! The inclination of the scapular segment having a marked influence only upon the speed, the straight shoulder is accepted in the motor which works exclusively from the weight of the mass. In a rapid motor, these defects will increase whenever the height over the withers is low, and, particularly, when the latter conformation is due to the low attachment of the trunk between the anterior members. Their free movement being already prevented on account of the 212 THE EXTERIOR OF THE HORSE. defective direction of the shoulder, these members will be advanced with much more difficulty, as they will be required to support a greater portion of the body- weight. Under these circumstances, if the animal be able to perform good service at the gallop or the trot on level roads, he becomes dangerous in descending hills or on rough roads, and is predisposed to stumbling and falling when he increases his [speed. Finally, the shoulder merits our attention from a point of view of the modifications which may supervene in its direction. According to the mode of subsistence or the employment of the region, it becomes straight or inclined, oblique or straight, as it was at first. A long time ago, Ch. de Sourdeval, in the Journal des Haras, had already recognized the influence of the attitudes which animals assume to obtain their nourishment. This accurate observer has proved that the shoulder becomes more vertical in those which are obliged to eat from the ground, or which are maintained in pasturage, whilst it becomes more oblique in those which are fed in the stable and receive their food from a high manger. Besides, a majority of horsemen think that a proper dressing of the saddle-horse in the riding-school will in- cline the scapular segment to a notable degree, and that the continuous pressure of the collar will straighten the shoulder of the draught-horse. This is also our opinion. Position. It suffices not that the shoulder be long and well directed, it should also be properly placed against the vertebral col- umn, that is to say, so situated as to maintain a proper separation between itself and the croup. When this condition is not fulfilled, the vertebral column is too long, lacks force, transmits the impulsive action of the posterior limbs feebly,, and becomes sway-backed as a consequence. This defect, very common in draught-horses, is nearly always accompanied and complicated by a vicious direction and insuffi- cient length of the scapula, which is then called short, straight, or for- ward. We can determine that it is not so by measuring the distance between the dorsal angle of the scapula and the angle of the haunch. In a natural conformation this distance is about equal to the length of the head, while in disproportionate subjects it may measure one- fourth or even one-third more. (See Proportions, length of the body.) Volume or Muscular Development. The volume of the muscles of the shoulder is an indispensable element of its beauty, whatever may be its relative function. This qualification has different degrees, dependent upon the race, the temperament, and the mode of rearing and subsistence. The muscles of the English thoroughbred are ANTERIOR MEMBER. 213 more remarkable for the density, fineness, and cleanness of their fibres than those of the heavy Percheron, in which they are voluminous, short, and separated by an abundance of connective tissue. In the one case, the muscles communicate to the region a long, slender, and graceful appearance ; in the other, it is the mass, the volume, the power. We should never demand a muscular development which changes all in all the conditions of its intended utilization. When the osseous eminences of the shoulder, especially its scapular spine, its point, its tuberosity, its dorsal angle, and its cartilage of pro- longation, form a prominence somewhat marked, which allows us to surmise the situation of these parts, it is called well outlined. This is the form which it presents in all horses belonging to the finer breeds. When, on the contrary, the same reliefs are very apparent under- neath the skin, from the effect of a commencing emaciation or muscular atrophy, as is observed in horses exhausted by fatigue or privations, it is called meagre or lean, and expresses a certain feebleness of the loco- motory apparatus. When, finally, this emaciation is such that the scapula can be almost completely outlined under the integument by its reliefs and its general configuration ; when the situation of the super- and sub-spinati muscles is manifested by a deep depression ; when the scapular cartilage is delimited above by a prominent curve from before to behind ; when, in a word, the region as a whole overhangs, so to speak, the adjacent parts of surrounding regions, as the neck, ribs, withers, back, it is called atrophied. Conversely, if the muscles, instead of being deficient in bulk, ex- ceed a yolume compatible with their special service, a volume demanded, besides, for general harmony ; if, for example, they affect, in the saddle- horse, a volume which would be sought for in the draught-horse, they will render the movements clumsy by surcharging the anterior part of the body, oppose themselves to the complete extension of the ante- rior member, and diminish the force of propulsion engendered by the hind limbs in rapid locomotion. In these conditions the shoulder receives the appellations of massive, fleshy, thick, charged with too much muscle, etc. Diseases and Blemishes. These are denudations and excoriations, due to a mal-fitting collar, which may terminate in smooth or radiating cicatrices formed by a portion of the skin which is deprived of its hair, thinner, irritable, and much less resisting to friction. The seat of these wounds is at the level of the anterior borders of the shoulders, where they appear flat and circumscribe the base of the neck. Horse-dealers never fail to point to these as a proof that the horse is free in the collar. Of but little gravity in themselves, they consti- tute, nevertheless, a cause of depreciation in view of the increased sensitiveness 214 THE EXTERIOR OF THE HORSE. which they give to the parts and the difficulties which are afterwards experienced in the application of the collar. At other times, this region may be the seat of cold abscesses, disabling the horse for a variable period during their formation. These are sometimes true fibromata, from the induration of the subcutaneous connective tissue. Of a chronic character at first, they soon become so sensitive to the pressure of the collar as to render the most docile horse intractable. The most serious of these tumors are those at the point of the shoulder, from the fact of the enormous volume which they may acquire, the dangers which their extirpation presents, and the difficulties experienced in healing the consecutive wounds, which are always more or less deep. They are caused by the pressure of a collar badly adjusted, insufficiently padded, or too heavy. It is not necessary to confound these tumors with diffuse enlargements of the scapulo-humeral articulation, as, for instance, with the particular affection known under the clinical but improper names sprained shoulder, shoulder-slip, which is accompanied by a lameness in which the anterior member is markedly abducted when it is extended, instead of moving in a direction parallel to that of the body. This movement, which is called mowing, is due to the immobiliza- tion of the arm upon the shoulder or the sides of the thorax, and is a symptom of diverse lesions of the ligaments, the muscles, the bones, the blood-vessels, or the nerves. Although this phenomenon may be quite rare, the point of the shoulder none the less often carries the evidence of the treatment employed to combat it. Such are the marks of cauterization, setons, rowels, and blisters, which occasion decortications, accidental white spots, or cicatrices of a particular form upon a more or less extensive area of this region. The gravest blemishes, above all, are traces of the actual cautery, except in the Barb horses, in which this therapeutic agent is always applied as a means of prevention against diseases of the articulation. It is important, in such cases, to examine carefully the inferior portion of the corresponding member, for the scapular lesion may be a feint for another disease, or, what is more frequent, an indication of an error of diagnosis. Let us mention, also, paralysis of the shoulder and atrophy of the super- and sub-spinati muscles, which are sometimes observed, but which produce no lame- B. The Arm. Situation; Limits; Anatomical Base; Form. The arm, slightly detached from the trunk, is situated between the shoulder, with which it is confounded, and the/orearm, from which it is separated by an oblique furrow in front. Limited in front by the breast and the axilla, behind by the sides of the thorax, and lower down by the elbow, it contains for its osseous base a long and voluminous bone, the humerus, surrounded by two sets of muscles : the first, coming from the shoulder, the neck, the side of the thorax, and the sternum, moves this region in every direction ; the second, extending to the forearm and the foot, regulates the movements of the inferior segments of the member. Movements. When the thoracic member is carried forward, as in walking, the humerus is first flexed, then its inferior extremity ANTERIOR MEMBER. 215 describes an arc of a circle forward to increase the opening of the scapulo-humeral angle. It is not, as our distinguished colleague, M. Chenier, 1 has said, that the humeral extension is terminated at the end of the phase of contact, but it is at the end of the elevation, when the foot is being placed on the ground, that the two bones (humerus and scapula) attain their maximum separation. The same phenomena are true of the member of the opposite side; the angle is closed by the, approaching of its branches until the step is about to be terminated, when the arm is extended. Length. We will not consider the details of this particular ele- ment as we did in the case of the shoulder. The arm should be as long as possible, relatively, in order to give greater length to its muscles which attach to the radius, and to permit its inferior extremity to describe an arc of a larger circle. But its length will be defective when it becomes excessive, that is to say, disproportionate relative to that of the shoulder. In this instance, as we have seen (see Fig. 58), the arc which it describes is not augmented. The foot will pass over a smaller space of the ground surface ; the movements are not executed with freedom ; the animal is disposed to stumble and fall, at least, if the shoulder be not long and oblique. It is therefore apparent that, in relation with the latter region, the arm should be short to give the necessary extent and rapidity to its oscillations. According to our measurements, confirmed by those of MM. Colin and Duhousset, the distance between the point of the shoulder and the centre of the humero-radial articulation should be equal to one-half of the length of the head in draught-horses. In rapid motors, like the trotter or the running-horse, it is, on the contrary, nearly always longer. It is important to recognize this dimension from a point of view purely artistic, because sculptors and painters, says Colonel Duhous- set, 2 have committed grave errors from antiquity even to the present time. Nearly all represent the humerus too long, placing much too high the point of the arm, which should not extend beyond the level of the extremity of the sternum. While an exaggerated length of the arm constitutes a defect which is not always compensated, its shortness also produces deficiencies of an inverse order, and both are hinderances in that which concerns the rapid gaits. If too short, it accomplishes an insufficient extension ; its mus- cles contract feebly, and restrain the movements of the forearm ; the 1 G. Chenier, Analyse de la premiere Edition du present ouvrage, in Echo des soci6t6s et asso- ciation^ veterinaires, annee 1882. 2 E. Duhousset, Lecheval, Paris, 1881, p. 67. 216 THE EXTERIOR OF THE HORSE. elevation of the anterior 'members, when the animal is in locomotion, becomes exaggerated, an elevation which is executed at the expense of the length of the step. Whence a loss of time which, insignificant as it may be at each step, eventually determines a marked diminution in the total quantity of speed. Direction. The direction of the arm is indicated by an imagi- nary line which joins the convexity of the great trochanter to the centre of the external lateral ligament of the elbow. It should fulfil the principal elements, as follows : to allow to the scapulo-humeral angle, already reduced by the obliquity of the scapula, a sufficient magnitude, and not to alter the direction of the vertical line in relation with the radius. We estimate, from our researches, that a mean inclination of 60 degrees is favorable to the development of velocity. When the inclina- tion passes beyond these figures, it must be compensated by an aug- mentation of the scapular obliquity. In the draught-horse, whose scapula is more straight, the humerus does not suffer by becoming more oblique. In the more active draught-horse it is intermediary between the two preceding types. The data furnished by instantaneous photographs of animals in locomotion 1 show that the limit of extension of the humerus is very close to the vertical line passing through the scapulo-humeral centre. Theoretically, therefore, the arm should not be too straight at repose, that is to say, in such a position that the line of direction of the mem- ber is too close to the verti- cal line passing through the centre of the suspension of this member to the trunk. When the conformation is thus, the extension of the humerus is necessarily limited, and such an arm cannot profit by the advantages of a long shoulder. It is true (Fig. 63) that the segment OB', for example, must pass through much less space to FIG. 63. 1 See the figures of MM. Marey and Pages, reproducing the details of the oscillation of the members in the gaits. ANTERIOR MEMBER. 217 reach the vertical axis OX than the segment OjB, supposed to be well directed. With the latter, however, the forward oscillation will be greater, and it will correspond better with a long shoulder, which, as we know, determines the degree of its displacements. If it be too oblique, on the contrary, as OB" , it does not bring the humero-radial articulation sufficiently in advance to permit the forearm FIG. 64. Scheme of the muscular incidences in the straight arm, A, and in the oblique arm, B. 1, Extensors of the humerus ; 2, flexors; 3, flexors of the forearm ; 4, extensors. and the canon to evolve themselves completely. It obliges the horse to multiply his movements and elevate the members excessively, instead of being advanced without describing too great a curvature, a loss of both time and energy. But a very oblique arm gives a better insertion for the muscles than a straight one, as can be demonstrated by an examination of the two diagrams (A and B) of Fig. 64, upon which are indicated the flexors and the extensors of the humerus and the radius ; its muscles, however, are shorter. It is also not disadvantageous in horses from which great force is exacted. The degree of brachial inclination, on the other hand, having an 218 THE EXTERIOR OF THE HORSE. FIG. 65. influence on the value of the scapulo-humeral angle, it may be asked if, for velocity or speed, a straight shoulder will not in a measure be compensated by an excess of obliquity of the arm. In other words, is it rational to prefer (Fig. 65) an angle AOB to an angle COD, both having the same dimension? Evi- dently it is : to a straight arm an oblique shoulder; this is the law, and for several reasons already known. We will recall them : An oblique shoulder will augment the elevation and extension of its point, from the same quantity of muscular contrac- tion ; whence it follows that the in- ferior extremity of the member will be carried more in advance of its primitive position. As the straight- ening of the humerus also tends to the same result, the two acting in uni- son will increase the total amplitude of the movement. If, on the contrary, the conditions be the reverse, if the arm be very oblique and the shoulder straight, the scapulo-humeral angle, although equal to the preceding, will be restrained to a less separation of its branches, because the extremity of the shoulder and the humero- radial articulation will remain too far backward in order to give to the forearm and the canon the ease and the time to be carried sufficiently far in advance. To recapitulate, the inclination of the humerus should not be exces- sive in rapid motors, and the conditions of a good orientation of the scapulo-humeral angle must be found in the obliquity of the shoulder. This explains why certain subjects, well marked in appearance in relation with their articular angles, do not confirm the conclusions which are based upon them. It suffices not (as we have seen on page 191) that the angles may have freedom of action, but it is also neces- sary that this action may be effected in the direction of the movement. If their orientation in relation with the vertical line of the centre of movement is defective, all the mechanical advantages for the accom- plishment of our aim, speed, are lost. These considerations, upon which we have purposely insisted, are not applicable to services which only exact strength. We will except,, however, the rapid draught-horse, in which the elements of force seem ANTERIOR MEMBER. 219 to be dependent on the phenomenon of speed. The inclination and the disposition of the articular angles will also very often enable us to judge the amount of thoroughbred blood in such animals. It is, by no means, not the same in slow draught-horses. We frequently meet in them a straight shoulder supported on an oblique arm. The obliquity of the humerus in such cases is not a defect, for it favors the power of the muscles by rendering their insertions more perpendicular. The shortness of the step, the inevitable consequence of such a con- formation, offers nothing of special interest, since, in motors of this nature, the ultimate purpose does not consist in the extent but in the power of the eifort produced. Direction of the Arm in Relation with the Median Plane of the Body. The long axis of the arm, in order that its displace- ments may be effected properly, should be almost parallel to the median plane of the body. If its inferior extremity is directed too much out- ward, the whole member is deviated in the same degree, the relation of the vertical lines is disturbed, and the foot is turned inward. This is called cross-footed. If, on the contrary, the elbow be deviated inward, the inferior part of the limb is turned outward (see crooked- legged horse). We will again refer to these a propos of the axes. Muscularity. The development of the muscles is an absolute beauty. It is preferredly appreciated by the prominence and width, of the olecranon muscles (extensors of the forearm), wnich occupy the triangular space between the scapula and the humerus, and by the relief formed by the humeral biceps in front of this region. Diseases and Blemishes. The region of the arm is, in most instances, exempt from these lesions. Contusions and, more rarely, fractures, the result of kicks received from other horses, when they are worked in file, running in pas- ture, in public exhibitions, or during transportation on railroads, are the principal alterations of this nature which are observed in this region. Rupture of the fibres of the coraco-radialis muscle is sometimes a cause of lameness. C. The Elbow. Situation ; Limits ; Anatomical Base. The elbow, situated between the arm and the forearm, and in front of the xiphoid region, has for its base the superior extremity of the cubitus, a voluminous apophysis called the olecranon. It gives attachment principally to the extensors of the forearm. The elbow offers for consideration three elements : its length, a good direction, and its freedom from blemishes. Length. The osseous process which forms the olecranon repre- 220 THE EXTERIOR OF THE HORSE. FIG. 66. Reproduction from an instantaneous photograph. sents the arm of a long lever for the muscles to which it gives attach- ment. Charged to maintain, during station, the summit of the humero- radial angle continually tend- ing to become closed from the pressure of the body- weight, and to produce ex- tension of the same angle in the propulsion of the trunk (Fig. 66), and, finally, to bring the antibrachial re- gion into its primitive posi- tion, during locomotion, these muscles act so much the more favorably as the arm of the lever in ques- tion is longer and more curved backward. Prefer- ence should therefore be given to an elongated and prominent elbow, rather than to one which, in a word, encroaches much upon the arm. Direction. The direction of the elbow is related to that of the arm. It is considered fine or beautiful when it occupies a plane par- allel to the axis of the body, and when, besides, this plane is suffi- ciently separated from the lateral faces of the thorax. The elbows are then said to be well separated and well directed. If, from the feeble development of the muscles which separate the anterior limb from the ribs, the region in question, although always parallel to the median plane, is too close to the thoracic walls, the horse has the elbows on the body. It then lacks vigor, energy, and amplitude of the breast. When the elbow is turned outward, the inferior extremity of the member is deviated inward, which characterizes the animal as being pigeon-toed ; if, on the contrary, the elbow is turned obliquely inward, the foot is directed outward, and the animal is said to be outbow-footed. Each one of these directions is vicious, because it renders the movements of locomotion ungraceful, disturbs the vertical axis of the members, predisposes them to premature ruin, even including the effects from speedy cut and interfering. Freedom from Blemishes. Wounds of the region of the elbow may be the consequence of the improper application of the belly-band, when the horse is worked in the shafts, particularly of two-wheeled vehicles or the cart. Most frequently they are due to the mode in which the decubitus is effected. ANTERIOR MEMBER. 221 Certain horses have the habit of lying down like a cow, that is to say, of main- taining the anterior members flexed under the chest. It results from this that the heels of the shoe come into direct contact with the point of the elbow, irri- tate and bruise the skin, and cause the formation of a more or less voluminous tumor called shoe-boil, so named from the agent which acts as the exciting cause. A turner of this kind is sometimes sensitive to the touch, and necessitates suspen- sion from work. At other times shoe-boils are not harmful, except as being ugly blemishes. We have had under our observation for several years a horse which performed very active service and carried on each elbow a shoe-boil of the volume of a man's head. As soon as any excoriation of the skin of this region is perceived, it is neces- sary to observe the position of the animal in the decubitus, and, if require'd, to shorten the heels of the shoe, or simply the one on the internal side, which alone is most usually the cause of the " boil ;" or, again, we may protect the foot with a leather boot. We may here mention fractures of the olecranon ; these are followed by a permanent deformity of the elbow, the extremity of the bone being displaced upward by the contraction of the extensor muscles of the forearm. Even after the fracture is repaired, this injury causes a lameness the nature of which can always be detected by careful observation. D. The Forearm. Situation ; Limits ; Anatomical Base. The forearm, situ- ated between the arm and the knee, is related, above and behind, to the elbow. Two bones constitute its base : the radius and the greater portion of the cubitus. These bones are surrounded by two sets of muscles, which all act upon the metacarpus or the phalanges ; the one, the anterior, compressing the extensors of these regions, and the other, the posterior, forming the flexors of the same. Indirectly, through the ligaments, they can also move the forearm, and carry it into extension or flexion, according to the muscles which act. They operate for the most part upon levers of the third class, and hence play their principal role in the production of velocity ; rarely do they concur in an active manner in the support .of the body, a function provided for by the special mechanical conforma- tion of the parts. Form. The forearm, as a whole, has the form of a cone, depressed from side to side towards its base or superior extremity, whose volume is in relation with that of the muscles just named. Its external face is separated from the arm and the elbow by a furrow, with an inferior convexity, due to the prominence of the extensors of the forearm upon the superior extremity of the antibrachial muscles, extensors of the meta- carpus, and phalanges. A gutter, extending along the external border of the radius, and in its lower part, separates the anterior from the posterior muscles. The internal face is devoid of muscles over the greater portion of its extent, and the skin is applied almost directly against the radius. The internal subcu- taneous vein of the forearm, on which phlebotomy is sometimes practised, crosses this face a little obliquely from below to above. Finally, in the lower third of 222 THE EXTERIOR OF THE HORSE. this region, we meet a horny excrescence to which has been given the name chest- nut. It is small in animals of fine breeding. The anterior and posterior faces, convex from side to side, are covered by muscles ; their thickness is proportional to the volume of the latter. Movements. The forearm, from the mode of union of its two bones with themselves and with the humerus, can execute only two principal movements : extension and flexion. The first, whose extent is directly proportional to the length of the bones concerned and the degree of openness of the humero-radial angle, carries the knee forward and upward, and enables the anatomical foot to be moved in advance. This is accomplished just before the foot touches the ground. The second takes place principally during the latter half of the phase of contact, as is shown by instantaneous photographs. It con- tributes, therefore, in a certain measure to the impulsive forces, since in this period the member, as a whole, is directed obliquely downward and backward. Beauties. In order to be in the most favorable conditions for the production of velocity, the forearm should be long, wide, thick, and well directed. Length. The length of the antibrachial lever should be con- sidered from two different points of view : the one considers the absolute length ; the other, its length as compared with that of the canon. a. Absolute Length. The absolute length of the forearm should be as great as possible, for the reason that the arc which this segment describes by its extremity is proportional to its length ; also, because this length implies a corresponding length of the muscles which cover it. It is upon these two factors that the velocity, in so far as it is produced by the structures of this region, principally depends. If the forearm be short, its oscillation, it is true, will be more rapid, but the distance passed at each step will be less. It can only preserve the velocity by a greater frequency of the movements, at the expense of a loss of time and more fatigue. Again, the knee being more elevated, the whole limb will be raised rather than projected for- ward ; the animal will trot upon place, but with a short forearm the movements will be more brilliant, easy, and harmonious, and the horse is said to have high knee-action. In the cavalry horse, or in those used in riding-schools and parades, this is, without doubt, a matter of beauty, but perfection in this respect makes the horse more manageable, and is therefore a useful qualification. A horse with a high knee- ANTERIOR MEMBER. 223 action will be less disposed to stumble, will more easily overcome obstacles in his way, and will be fitted for special varieties of work, but will never be possessed of great speed. Horses provided with long forearms move their members closely along the ground, and thus offer less safety to the rider on uneven roads. An intelligent handling and a rational training will nearly always cause a disappearance, or at least an attenuation, of most of these disadvantages of a long forearm. b. Length in Relation with the Canon. Nearly all authors agree that the radio-metacarpal segment should owe its length to the forearm or its superior section, and not to that of the canon. In other words, from a point of view of speed, the conformation should be such as to present a long forearm and a short canon. The relative length of these regions varies in a small proportion when they are measured in a large number of horses of the same height at the withers. But the few centimetres by which these figures differ are sufficient to produce a very marked effect on the value of the movements at the extremity of the member. Professor Neumann l was the first one to remark that if the metacarpus be considered just before the foot is raised, when the region is inclined downward and backward, it will be seen that the latter plays the role of a lever, upon the superior extremity of which the weight of the body is decomposed into two secondary forces : the one, perpendicular to the canon, tends to carry the knee forward ; the other, parallel to this segment, indicates the intensity with which the foot presses against its point of support, the ground. The latter force, antagonized by the resistance of the soil, offers but little of interest to us in the present discussion. The former force acts behind on the arm of a lever, the metacarpus, antagonized in front by the extensor muscles of this region. It follows, then, that the shorter this arm the less will be the eifect of the force in question and the less the fatigue of these muscles in combating the tendency to flexion. A member with a long forearm will support the body more easily during contact for a longer time without a greater expenditure of force, and will incline itself more before being raised from the ground, a condition which will enable the foot to describe a larger arc and increase the length of the step. If the inferior extremity of such a forearm, having reached its limit of inclination, be now flexed, it will describe, for an equal angu- lar displacement, a greater quantity of movement, and the latter is always proportional to the speed acquired, which is itself in direct 1 G. Neumann, De 1'avant-bras du cheval et de 1'influence de sa longueur sur la rapidity des allures, in Journal de me'decine veterinaire militaire, t. xi., annee 1873, 1874, p. 157. 224 THE EXTERIOR OF THE HORSE. ratio with the distance passed over in a unit of time ; but the exten- sion of the canon taking place after the flexion of the forearm, the quantity of movement of the latter will tend to augment that which the antibrachial muscles will communicate to the canon, in order to favor the rapid and extensive projection of the inferior part of the member. It is, therefore, also necessary to seek for a great development of the forearm in the parts where the muscles are situated, since the degree of muscular shortening gives the measure of the angular displacements of the bones. For this reason it is preferable to have a short canon in relation with the forearm. From a point of view of locomotion, it is just to say that, of these two segments, the one is active and the other passive ; the first, by its mobility, overcomes the inertia of the second. Finally, with a short forearm, the displacement of the knee is effected upward instead of its being projected forward in the direction of movement. The arm of the lever (radius) of the resistance (weight of canon) diminishes, whilst the intensity of the power (flexors of the radius) remains the same, which favors so much the latter and gives to it more facility to elevate the knee. With a long radius, the arm of the lever (radius) of the resistance (weight of the canon) augments, and the power (extensors of the metacarpus) remains invariable, a con- dition which favors this bone again and disposes it more favorably for the extension of the canon. This is the reason w r hy, in the first case, the knee-action is exaggerated, the members badly employed and not properly advanced ; also why, in the second case, the knee is not unduly elevated, the segments being at the same time well projected forward. The animal thus acquires more speed without increasing the rapidity of his efforts and without compromising the integrity of the locomotory apparatus. Width. It suffices not that the forearm should merely be long, but it should also be wide, this wideness being an indicator of the volume of the muscles. This width is measured from before to behind below the elbow, viewing the horse in profile, at a point always a little superior to the widest part of the tibial region, x and at the level of the most prominent portion of its anterior muscles ; it is, finally, on the same level as that of the tibial region at the point where the latter receives the insertion of the fold of the buttock. The forearm has such a conformation in well-formed horses, which qualifies it imde y muscular, well muscled. ANTERIOR MEMBER. 225 The tendons which terminate, under such conditions, the posterior radial muscles are short and thick ; they are well separated from the canon and favorably disposed to fulfil their function of support in relation to the fetlock. The antero-posterior diameter of this region should be considerable, in the draught-horse more than in any others, since it is in relation with the contractile force of these muscles,' pro- vided they are dense, firm, and poor in adipose and connectiveJissues. When the forearm offers dimensions opposed to the preceding, it is defective by reason of its small volume, and is called slender. The slender forearm characterizes ordinarily a horse without energy, with long, disproportionate limbs, vulgarly called weedy ; he lacks strength and firmness, and, in general, is defective in most instances in the other regions. Thickness. The thickness, in close relation with the width, is measured from side to side, viewing the region from in front. It is recognizable by the prominence which the anterior antibrachial muscles form externally. It is desirable to have the thickness as extensive as possible, for the reasons which we have previously indicated. It may be remarked, nevertheless, that the forearm does not have the same muscular development in the thoroughbred horse as in the draught- horse ; the region appears flat in the former, whilst it seems rounded in the latter. Direction. The direction of the forearm is as important a characteristic of its beauty as its length and its breadth. It should be vertical when the horse is examined in profile, and parallel with the median plane of the body when he is viewed in front. The vertical axis in this case is not altered, and the members are well placed to support the weight of the body. If the inferior extremity of the region be directed forward or backward, outward or inward from the vertical line, the direction is vicious ; certain parts of the limbs become exhausted and prematurely ruined, to which we will again refer in speaking of the knee and the vertical axes, because any deviation of this nature, altering the vertical position of the segment, demands an increase of function of the muscles equivalent to the part of the weight which is no more supported by the bones themselves. It is not without interest to present here the details of the rdle which the direction of the arm plays in the effective utilization of the antibrachial movements. The angle formed by the two segments depends upon the more or less marked degree of inclination of the humerus. When the latter approaches the horizontal, this angle is so 15 226 THE EXTERIOR OF THE HORSE. much more closed than when the bone in question is more vertical. In order that the horse may have speed it is necessary that the forearm be not only long but that it be also enabled to become flexed to a large degree, so as to give the greatest possible amplitude to the step. The more vertical the arm the better will this condition be fulfilled. Such a disposition will, besides, favor the opening of the humero-radial angle during the propulsion of the trunk, another qualification which all the articular angles of rapid motors possess. Here observation con- firms the theoretical data presented in discussing the arm. In race- horses the latter region is not inclined, a disposition which, as we have seen, is not incompatible with an extensive closing of the scapulo- humeral angle, since the obliquity of the scapulum counteracts the disadvantages which result from a vertical humerus. These slight variations in the direction of the bones and the mode of opening of the superior articular angles of the members contribute to explain the contradictory results which are observed in race-horses of the best appearance as to conformation. Very difficult to appreci- ate, these variations often pass unperceived and lead the observer into error as to the importance of their effects. These, nevertheless, may sometimes be quite considerable, as we shall presently see. Let us suppose, for an instant, that a horse be able, at each step, to open the scapulo-humeral angle and close the humero-radial, each to a greater degree than in another horse. Let us assume, also, to make use of round numbers, that this feeble amplitude of two degrees is manifested upon a lever only one metre in length. We know that the distance passed over by the extremity of this lever for each degree will be : 2irE 2 X 3.1416 - This will signify that each step of this horse will be 34 millimetres longer than that of the second horse. These 34 millimetres will give him an increase of 22 metres and 644 millimetres over a distance of 4000 metres travelled at a fast gallop (the step measuring 6 metres) ; at a fast trot (the step being 3 metres), an increase of 68 metres. Thus, the influence of the articular angles merits to be taken into consideration, in that they can determine the amount of speed which a given animal is able to employ. As it has been well remarked, we must take cognizance of only a very feeble augmentation for a very short lever, as in the example which we have chosen. What might have been the results if, instead of calculating them upon two degrees, we had estimated them upon four, six, or eight, as it frequently exists ? ANTERIOR MEMBER. 227 Diseases and Blemishes. These are wounds, the result of kicks upon this region from other horses, but which are only grave when they interest the internal face of the region, where the bone, as we know, is directly subcutaneous and not covered with muscles. In this situation they are often complicated by fractures of the bone. At other times, synovial dilatations, which proceed from the upper extremity of the region of the knee, may exist here, but these appear upon the forearm only when they have reached a large development. Those of the humefo-r-adio- cubital articulation are extremely rare, and, in our experience, we have seen only two examples. They manifest themselves posterior to the external lateral liga- ment of this joint, and can be clearly seen when the member is placed upon the ground. They then acquire a volume equal to one-half of that of a hen's egg, and disappear altogether when the limb is raised. Finally, let us mention the wounds which are located upon the external lateral ligament of the humero-radial articulation. The external side of the joint forms a prominence, projecting above the level of the surrounding surface, which is continually being bruised, and receives most of the pressure when the animal assumes the decubitus for a long time upon a bed with insufficient litter. These wounds are very grave, for they may be complicated by an opening of the articulation and terminate in the death of the animal. The defects of direction, true blemishes, we will study with the vertical axes of the members. E. The Chestnuts. The name chestnut is given to a horny production, more or less voluminous, according to the race, situated upon the middle part or the inferior third of the internal face of the forearm. But little developed in the finer races, it is large in common horses, in which it is habitually cut or peeled off in arranging the animal's toilet before presenting him for sale. The absence of the chestnuts in the -anterior members has been observed, but it is a very rare fact. (The chestnuts are the rudiment of the nail or hoof of the internal digit or thumb.) F. The Knee. Situation. The knee, corresponding to the wrist of man, com- prises all the radio-carpo-metacarpal articulations. It is at this region that the anatomical foot commences. It is also the region where the anterior member is almost completely divested of its muscles, and is constituted by nothing but the bones, the tendons, and the ligaments. Limits ; Anatomical Base. Limited above by the forearm and below by the canon, this region has for its osseous base the seven carpal bones arranged in two superposed layers. One of these bones, the first and the most external of the four of the superior row, also called the supra-carpal, is situated somewhat 228 THE EXTERIOR OF THE HORSE. without the region, and forms behind a more or less pronounced elevation under the skin. Several special ligaments, short, strong, and numerous, unite the bones of the same row to one another ; others maintain the two rows in contiguity, or concur to fix the one or the other to the forearm or the canon ; finally, the common liga- ments, which are much longer and more resisting, and common to all the carpal articulations, appear to assume the role of insuring general solidity of the whole region. Among the last, two are lateral, funicular, which circumscribe the carpus within and without, and extend from the tuberosities of the radius to termi- nate on the head of the rudimentary metacarpals ; the other two are capsular : the one, the anterior, is thin, more particularly charged to sustain the synovial membrane of the joint and to furnish gliding surfaces for the tendons which pass over the anterior surface of the knee ; the other, the posterior, much more fibrous, extremely thick and resisting, fills up all the irregularities on the pos- terior face of the carpal bones and transforms this face into a veritable sheath, the carpal sheath, which is completed posteriorly by the supra-carpal bone and an arch of fibrous tisssue, in which are lodged the flexor tendons of the pha- langes. This ligament, one of the most powerful in the organism, is prolonged at its inferior extremity by a strong band to constitute the check tendon, Avhich is inserted into one of these tendons (that of the deep flexor), and plays a mechan- ical but important role in supporting the fetlock and maintaining its angle. Three synovial membranes lubricate the articular surfaces and facilitate their movements. They are everywhere firmly surrounded by the ligaments as well as the extensor tendons of the foot, excepting at certain places where they are more feebly supported, and become the seat of abnormal dilatations. We will refer to these in discussing the blemishes. The anterior face of the carpus is traversed from above to below by two principal tendons, which are maintained there by means of special synovial sheaths : one of them is that of the anterior extensor of the metacarpus, the other that of the anterior extensor of the phalanges. The external face is traversed by the tendon of the lateral extensor of the phalanges ; the internal face by that of the internal flexor of the metacarpus. Finally, upon the posterior face of the region is located the vast carpal sheath, whose synovial membrane covering its walls and reflected upon the two tendons of the flexors of the phalanges, ascends on the posterior face of the radius to about its inferior fourth, and descends against the metacarpus to the lower limit of its superior third. Although strongly surrounded above by the muscular cone of the flexors of the metacarpus and the antibrachial aponeurosis, below and in its middle portion by the carpal arch, it nevertheless becomes apparent, when it is the seat of abnormal distentions in the form of tumors, whose exact characteristics and situation we will indicate farther on. The movements of the canon on the forearm mechanically excite those of the knee ; they consist of flexion and extension. The first is produced when the foot is elevated from the ground and before it is advanced to complete the step. It is worthy of remark that the inferior extremity of the member, instead of moving in its own plane, is deviated out- ward in consequence of the obliquity of all the articular surfaces, and is not thus exposed to come in contact with the posterior face of the forearm. ANTERIOR MEMBER. 229 The second only takes place when the member, sufficiently relieved from the weight it supports, is projected forward to complete the step and assume its con- tact. It has attained its extreme limit as soon as the two segments are placed in a straight line, as they were during station. As to the displacements which the carpal bones undergo, the one upon the other their importance is considerable in relation with the distribution of the quantity of force upon the metacarpal surfaces. Their multiple facets, indeed, represent so many inclined planes which deaden the concussion and disseminate it upon the powerful ligaments which unite these bones. Form. The anatomical details which we have summarily reviewed are indispensable in order to conceive an exact idea of the external aspect of a well- constituted knee. The skin, in horses of the finer and more nervous races, is thin, covers all irregularities of the region, and shows its contour with the most perfect details. Also it is in these that the characters of a beautiful conformation can be best studied. Viewed on the anterior face (Fig. 67, A), the knee appears slightly rounded from side to side, and a little wider above than below. It offers on its middle an B FIG. 67. elongated eminence, the termination of the tendon of the anterior extensor of the metacarpus. Two curved lines circumscribe it on the sides : the internal, very marked, commences at the tuberosity of the radius ; the external begins almost on the same level, but makes a less salient angle ; both terminate quite abruptly at the canon below the head of the rudimentary metacarpal bones. Examined in profile from the external side (Fig. 67, B), its anterior line, almost straight, continues that of the forearm ; two eminences, scarcely marked, modify it slightly and indicate the relief of the two rows of carpal bones. Its posterior line, on the contrary, presents a very pronounced angle, formed by the supra-carpal bone, below, which it curves obliquely forward upon the tendons. Between these two lines there are two prominences which indicate the external tuberosity of the radius, above, and the head of the corresponding splint bone, below. The branch from the tendon of the lateral extensor of the phalanges joining that of the anterior extensor is detached below the latter. 230 THE EXTERIOR OF THE HORSE. The profile of the knee from the inner side (Fig. 67, C) is very much similar to that which is seen from the outer side. It presents the internal radial tube- rosity, well outlined, the internal metacarpal vein, and the head of the internal splint bone. Finally, viewed from behind (Fig. 67, Z>), the lines which circumscribe it on the side are similar to those which we have described in connection with the anterior face, while in its middle it is traversed by a voluminous conical emi- nence formed by the insertion of the flexors of the metacarpus upon the supra- carpal bone. This relief, slightly depressed below the latter at a point called the fold of the knee, is continuous inferiorly, without any sharp demarcation, with the flexor tendons of the phalanges. Beauties. The knee, in order to be beautiful, must be fine, thick, wide, well situated, well directed, and free from blemishes. Fineness. This quality is one that, in a general manner, is desirable in all the articulations. It denotes that they are formed only of those parts which should constitute them. It resides in the appar- ent prominence of all the normal osseous reliefs, the ligaments and the tendons, which implies a thin and delicate skin, a small abundance and great density of the connective tissue which covers these structures. All horses belonging to the more distinguished races are noted for this peculiarity ; those of the common races present it in a small degree, and in nerveless and lymphatic animals it is absolutely defective ; the articulations in the last are always more or less poorly defined. Thickness. The thickness of the knee is its diameter from side to side. It is particularly desirable, because the lateral diameter is in relation with the transverse development of the articular surfaces, with the volume of the carpal bones, and, consequently, with the firmness of the step and safety of the gait. When this region is narrow, the animal is liable to stumble and to a premature ruin of his limbs, which are too feeble to support the weight of the body beyond a certain rate of speed. Width. The width is measured from before to behind, for the extent of the knee measures more in this sense than from one side to the other. A large width always indicates the antero-posterior de- velopment of the articular surfaces and a decided prominence of the supra-carpal bone. The effect of the first of these factors is to render the carpal bones more resisting, to augment the movements of flexion and extension, at the same time that it makes the inferior extremity of the radius appear larger, a disposition which separates the muscles from their parallelism with the bones and favors their action. The second only implies a longer arm of the lever for the flexors of the metacarpus. ANTERIOR MEMBER. 231 The knee is called calf's knee when it is defective in its width, its thickness, and in the eifacement of all the bony prominences ; it denotes a general feebleness of the member, the volume of an articulation being correlative also to that of the regions which confine it. Height. The height of the knee above the ground depends on the relative length of the forearm and the canon. We have seen that a long forearm gives a great advantage in the function of kmg anti- brachial muscles, and it is for this reason that preference should be given to a knee well descended and situated very low. In this con- nection, all other things being equal, saddle- and carriage-horses have the knee higher than draught-horses, a fact which can be easily ascer- tained by actual measurement. Their canons are longer, their body is less close to the ground. Nevertheless, tnis does not change the prin- ciple which has just been laid down. The latter applies only to those subjects whose conformation is comparable, and to no others. Direction. The vertical direction of the forearm and of the canon is without doubt one of the principal conditions of the strength and endurance of the anterior members. So true is this that everything in the carpal articulations is so ar- ranged as to determine this mode of superposition of the osseous segments. Such is, however, not always the direction of the knee : sometimes it is deviated forward or backward from the vertical line; sometimes it is within or without this axis. Hence grave defects of the axis of the member, to which are given particular names. Thus, the horse is called over in the knees, knee- sprung, when this region is curved forward (Fig. 68). This condition is also distinguished as acquired and congenital: acquired or accidental when it is the result of fatigue and excessive wear and tear of the parts; congenital, on the contrary, when it exists from the time of the animal's birth. The first case is a serious condition, indicative of the FIG. 68. muscular weakness of the part, of its worn-out state, or of the contraction of the posterior tendons ; such a horse is utterly un- steady on his feet, is positively unsafe to ride, and may fall on his knees at any moment, as is shown by the indelible scars with which they are usually disfigured. In the second case the defect is only apparent, and in no way inter- feres with a firm and steady grip of the ground or with the freedom of movements. 232 THE EXTERIOR OF THE HORSE. " In this class/ 7 says H. Bouley, 1 " we even find horses whose knees arch forward to such an extent, when they are standing still, that we wonder how they manage to hold themselves up ; and never- theless, even laboring under such an exaggerated form of this defect, they never stumble when once they have been started. The reason of it is that the remarkable attitude of these animals does not bespeak any weakening in the powers of their extensor muscles, as it does in the horse that has become knee-sprung through hard work and old age." Custom alone enables us to distinguish true or acquired sprung knees ; let us add that it is also revealed by the trembling of the knees when the horse is in a resting posture, as well as by the habitual pres- ence of hard or soft blemishes upon the inferior regions of the members. If, contrary to what we have seen, the knee deviates towards the back of the vertical axis (Fig. 69), it is termed effaced, sunken, hollow, or sheep-knee. This defect, characterized by a concavity of its ante- rior face and a more distinct prominence of the supra- carpal bone, has not, so far as we know, the importance, as regards speed, which some would attach to it. It necessitates, without doubt, a somewhat more extensive contraction of the flexors of the metacarpus, to bring that i region into the attitude required by normal flexion, whence a loss of time in the execution of the move- ments. This loss of time and of muscular force, which result from it, are insignificant and can hardly be appre- ciated. Such a conformation is vicious, rather in so far as it causes a continual tension of the posterior ligamentous apparatus of the carpus and the check tendon of the FIG. 69. perforans, a tension which tells likewise upon the lateral ligaments and becomes further increased at every instant of contact with the ground, when the animal is moving at great speed. These excessive tractions, injuring the articular ligaments, will eventu- ally bring about the formation of osseous deposits at the points of their insertion upon the bones, or else a permanent induration of the check tendon and the suspensory ligament of the fetlock. Considerations of a similar nature are applicable to a knee which deviates to the inner side of the vertical axis, and which is styled ox-knee, from its analogy to that of the animal whose name it bears (Fig. 70). Very convex upon its internal face and concave externally, r si 1 H. Bouley, Nouveau Dictioiinaire pratique de medecine, de chirurgie et d'hygiene v^teri- naires, t. viii. p. 201. ANTERIOR MEMBER. 233 FIG. 70. it is no longer compatible here with a uniform distribution of the body- weight upon the metacarpal region, because the articular surfaces in the horse's carpus have a slant different from that of the carpal bones in the ox. The inward deviation has a tendency to increase in the state of rest and at the time of contact with the ground during loco- motion ; the outer half of the bones is overloaded, while the internal lateral ligament is stretched to its utmost. Hence, for this reason, first and fore- most, do we look upon this anatomical conforma- tion as a vice of the greatest importance in car- riage- or in saddle-horses, the latter in particular. Moreover, during the act of flexion, it exag- gerates the movement of abduction of the meta- carpus, which, on the contrary, under ordinary normal conditions, is always very slight. At every step the animal throws the canon outside of the vertical axis, wastes a certain amount of time in bringing it back to its normal attitude, and uses his limb in a most ungraceful style, described by H. Bouley as " a kind of all-over-the-shop gait, displeasing to the eye of the true con- noisseur." Finally, the necessary consequence of this form of the knee is the outward deviation of the inferior part of the member, notably the hoof. \e will return to this in speaking of the outboiv- footed horse. (See Axes.) When the region of the carpus deviates to the external side of the vertical axis it is the seat of a grave defect, which is denoted by the limb being con- vex on the external side and concave inwardly, as well as by a convergence of the two hoofs (Fig. 71). This conformation is not common, but, like the pre- ceding, it causes unsteadiness in the " grip" of the ground and a straining of the ligaments. In this case it is the internal surface of the articulations which is overloaded, and the external lateral liga- ments that are subjected to the abnormal tension ; and for this reason blemishes are the speedy result of this form of the knee. Besides, as the toe of the hoof is turned inward, the horse is pigeon-toed and exposed, consequently, to all the evils of this defect, particularly interfering. FIG. 7L 234 THE EXTERIOR OF THE HORSE. Clearness of Outline. It is not sufficient that the knee be "dry/' wide, thick, Avell located, and set in the right direction, but it is absolutely indispensable that the outline be perfectly clear, that is to say, neatly denned in its external lines, whether viewed from the front or from the side. Any deformity, even a slight one, should be considered grave, for it is a sign of the weakness and the ultimate ruin of the limb in which it is noticed. Diseases and Blemishes. H. Bouley 1 has described the dis- eases and the blemishes of the knee in his usual happy style. We will therefore limit ourselves to condensing here what he has written on this subject. 1. Recent Lesions and Diseases. First among these are denudations, excoriations, and more or less deep wounds of the skin of the anterior surface of this region, the result of falls, and the gravity of which varies with the nature of the soil, the velocity of the gait, and the weight of the burden which the ani- mal carried at the time. These lesions, as well as the scars they leave behind, are, as a rule, somewhat circular in shape, on which account the horse thus disfig- ured is said to be crowned. The cicatrices which succeed them usually have quite a regularly circular form, and designate the animal that presents them crowned. It is important to ascertain whether they are the result of a lack of steadiness in the anterior limbs or due to accidental falls. It is likewise necessary to find out if the lesion of the knee has affected only the skin and the subcutaneous con- nective tissue, or if, on the contrary, the synovial bursse have been involved, for the gravity under these diverse circumstances is not the same. In general, super- ficial wounds are not accompanied by any great difficulty in walking, while the deep ones, those which have brought about the opening of the articulations, are extremely painful, and make it impossible for the animal to press his hoof on the ground. Sometimes injuries or falls have determined no other consequences than a simple excoriation of the epidermis and the hairs thereon, which latter will grow again with their natural change of color. At other times the region is more or less contused, without a loss of substance, and the extravasation of blood or serum underneath the skin will occasion the formation of abscesses capable of rendering the subjects incapable of service for some time. 2. Chronic Lesions and Diseases. In this category are arranged numerous lesions and affections, which, in most instances, are tantamount to true blemishes. They involve the skin, subcutaneous connective tissue, the artic- ular and tendinous synovial bursas, and the bones. Let us examine them rapidly. a. Skin. We have seen that the horse styled crowned may receive upon the anterior surface of the knees injuries of greater or less importance; but the skin only preserves permanent traces when it has been affected in its essential parts. The most trifling of these after-results are those which proceed merely from a modification of the hair-follicles. Where these follicles are the new hair grows white, and thus bears witness of the fall which has taken place. In other i H. Bouley, loc. cit. ANTERIOR MEMBER. 235 cases the integument has been injured more deeply or even partly destroyed, and then no new hairs grow when the cicatrization has been completed. In the eyes of the connoisseur the horse is no less blemished in the one case than the other, whether he has an abnormal white spot upon the knee or an indelible cicatrix deprived of hairs ; he is considered weak upon his limbs, predisposed to repeated falls, and, consequently, much depreciated from a commercial point of view, although, at times, the blemish may be altogether accidental. We should, there- fore, beware of the so-called recipes which horse-merchants never fail to~ recom- mend for the reproduction of the hairs. More especially should we be on our guard against the fraudulent means used by certain individuals for the purpose of concealing from the eyes of too credulous buyers a blemish which baffles all such attempts. Some have been known to go so far as to blacken the denuded spot with a particular blacking; others cover it rather skilfully with false hairs, which they temporarily keep in due position by means of a thin coating of dextrine ! As may be readily imagined, all these expedients are of such a nature as not to deceive the attentive and experienced observer. Fissures known under the name of malanders are met in the region of the fold of the knee. They are grave in so far as they cause much pain, and are often very tedious to heal. b. Subcutaneous Connective Tissue. It is not rare to observe more or less abundant effusions into the subcutaneous connective tissue as the result of contusions of the knee. The anterior face of this region is then seen to present a voluminous, fluctuating, and non-inflammatory tumor, whose walls, at first thin, soon become indurated and irregularly thickened ; this constitutes the hy grama, or cyst, of the knee. It sometimes becomes inflamed and very painful. As a general rule, it interferes with locomotion only in a mechanical manner, and is nothing more than an eyesore. Indurated tumors of the connective tissue have the same origin ; they differ from hygromata in the fact that they are not fluctuating and that they can be much more easily dissolved. c. Tendinous and Articular Bursse. A complex articulation like the knee, endowed as it is with such extensive movements, is sure to give signs of fatigue in the long run, by synovial dilatations at the level of the most mobile parts, that is to say, at the points where the gliding apparatus must needs have displayed an excessive and almost incessant functional activity. Indeed, that is what is observed in the radio-carpal and intercarpal articulations, in spite of the powerful union which protects them. Hydropsy or hydrarthrosis of the first manifests itself by the presence of two tumors, soft and fluctuating when the limb is semiflexed, and tense and con- vex when it is in extension. The one is situated immediately above the supra- carpal bone and against the radius ; the other forms at the upper part of the anterior surface of the knee. They correspond evidently, therefore, to the por- tions of the synovial membrane which are feebly supported ; pressure applied upon the lateral tumor is distinctly transmitted to the anterior, a fact which indicates the close relation which they bear to each other. Hydrarthrosis of the intercarpal joint is shown, when the foot is in contact with the ground, by the appearance of two or three nodosities of the size of a hazel-nut or a walnut, between the extensor tendons of the phalanges and of the metacarpus, almost over the middle of the anterior surface of this region. 236 THE EXTERIOR OF THE HORSE. When the articular dilatations of the knee are very old, their wall becomes indurated and even ossified. This constitutes, in the latter case, one of the varieties of hooped knee, of which we will speak farther on. The dilatations of the tendinous synovial bursce are of two varieties: they appear either along the course of the flexor tendons or along that of the exten- sors. Larger than the preceding, they may acquire very great dimensions. It sometimes happens, at least with the second variety, that they communicate between themselves or with the articular capsules, 1 an important peculiarity, which should warn us against the danger of opening them. Hydropsy of the carpal sheath, better known under the name of carpal or tendinous thorough-pin of the knee, is manifested by the formation of two tumors posterior to the carpus, between the radius and the flexor muscles of the meta- carpus. Each one of these is ovoid in shape ; the internal is ordinarily smaller than the external, and both extend higher up than the articular dilatation. Inferiorly, the tendinous dilatation is prolonged below the knee by a soft, elongated, and irregularly- lobulated swelling, which follows the course of the flexor tendons, and transmits its fluctuation and palpation to the two superior culs-de-sac, thus giving evidence of its communication with them. This is a cir- cumstance which is never noticed in the articular synovial dilatation. The synovial dilatations of the tendinous biirsse situated upon the anterior capsular ligament of the carpus present analogous characteristics. They con- sist of elongated tumors, from one to three in number, located under each of the extensor tendons, and always perfectly distinct at the beginning of their forma- tion. In advanced stages they become diffused over the anterior surface of the knee, and may communicate among themselves and with the articular synovial membranes; their parietes become indurated and, in some places, ossified. They might be easily confounded with the cysts, which are always more super- ficial, were it not for their relative situation with the tendinous cords. d. Osseous Apparatus. Xot even the osseous apparatus is exempt from the traces of the wear and tear resulting from age or from excessive work. Ex- ostoses appear, in time, upon the anterior surface of the carpal bones and upon their articular edges, at the points which correspond to the insertions of the lig- aments. These osseous tumors of the knee have received the generic name of osselets. Their formation begins at the head of the rudimentary metacarpal, preferably on the internal side, and then they gradually extend, little by little, to the pieces of the two rows. When they are thus generalized, it has been the custom to say that the knee is hooped, a very appropriate expression, which con- veys to the mind the idea of the alterations of which the region is the seat These osselets, like the tendinous and articular dilatations, are grave blemishes ; they disfigure the animal, produce a deviation of the forearm and of the canon, and, finally, often give rise to a rebellious and, very often, persistent lameness of variable intensity. As the regions situated below the knee and the hock offer but few differences in their anatomy and their external appearance, we will study them with the posterior members. 1 1 have examined a large number of articulations and have not once verified such a condi- tion. (Harger.) POSTERIOR MEMBER. 237 CHAPTER II. POSTERIOR MEMBER. WE have already stated the reasons for uniting the description of the croup with that of the trunk, and need not return to them itere. The regions of the posterior members correspond to those of the anterior, with some unimportant variations consequent upon the par- ticular mode in which these parts execute their movements. Thus, the thigh is the counterpart of the arm; the stifle, of the elbow ; the leg, of the forearm ; the hock, of the knee. Such are the diverse regions which it remains for us to examine. A. The Thigh and the Buttock. Situation ; Limits ; Anatomical Base. We deem it advis- able to combine the thigh and the buttock in one description, since there is so close a relation between them. We will merely consider the latter as that part of the former which is charged with the flexion of the tibia, the extension of the femur, and the rotation of the coxa. The thigh is the region where the posterior member becomes sepa- rated from the trunk. It is limited above by the croup and the haunch; below, by the leg and the stifle; in front, by the flank; inwardly, by the groin (in both sexes), the sheath and the scrotum in the male and the mammary glands in the female ; behind, finally, it is altogether free, and is simply in relation with the trunk and the hairs of the tail. Its anatomical base consists of the femur and of numerous muscles which, originating in adjoining regions, terminate here, or, on the con- trary, are detached here to terminate 011 the sections immediately below it, viz., the leg and the foot. Form. The thigh offers for study two surfaces and two borders. The external surface is slightly rounded, according to its length and its width, in a horse in good condition. It forms, in such cases, below the croup, an almost vertical plane, which blends off below with the corresponding surface of the leg, and, in front, with the side of the flank. But hard work and insufficient food render the muscular interstices and the natural prominences of the skeleton very apparent : the femur is indicated by a thick longitudinal elevation, in front of which the muscles appear hollow, in consequence of the contraction of the flank ; the ischiatic tuberosity and the trochanter become very salient, and leave between them a deep furrow which separates the superficial gluteus muscle 238 THE EXTERIOR OF THE HORSE. from the posterior ischio-tibial muscles, and which is known under the pictu- resque name of furrow of misery. The internal surface, called the/o^ of the thigh, is also more or less convex. It is traversed above in its direction and from back to front by a large vein, the saphena, on which phlebotomy is sometimes practised. This vein is accompanied by a small artery bearing the same name and covered over with a net-work of nerve-branches and of lymphatic vessels, whose situation it is important to re- member from a surgical point of view. The anterior border of the thigh is constituted by a voluminous muscular mass, the crural triceps, whose function it is to extend the leg. Over the middle and inferior portion of this border attaches a musculo-cutaneous fold, .which is called the fold of the stifle, and spreads over from the side of the flank to the anterior surface of the stifle-joint. As to the posterior border, it represents by itself the sub-region of the buttock or the breeching, and has for its base the ischio-tibial muscles. It describes, beginning at the base of the tail where it becomes continuous with the croup, a regularly-curved line, which becomes concave inferiorly and disappears at the posterior border of the leg. The most salient point of this graceful curve has received the name of point or angle of the buttock ; it is due to the prominence of the ischiatic tuberosity of the coxa. On the other hand, the/o/rf of the buttock is the most concave portion of this line, and corresponds about to the centre of flexion of the tibia on the femur. It is worthy of remark that in very emaciated subjects the point and the fold of the buttock are always strongly marked, while they are scarcely indicated in those that are in good condition, particularly in the heavy draught-horse, whose muscular system is voluminous. Viewed from behind, the thigh is thicker as its muscular masses are more developed and as the animal belongs to a race of a more lymphatic and less nervous temperament. Movements. This region, in relation with the movements which it executes, is most interesting to study. It describes two prin- cipal movements, whose centre is the coxo-femoral articulation : these are extension and flexion. Their maximum amplitude is about 30 degrees. During flexion, the femur is displaced angularly to begin the step. It reaches its limit of flexion a little before the foot arrives on the ground, so as to allow the full extension of the tibia, which has not yet been completed at the moment that the femoral flexion is accomplished. During extension, the phenomena have an inverse order : the femur moves backward, thus strongly opening the coxo-femoral angle ; its obliquity is changed in direction ; it becomes vertical or even inclined backward and downward when the limb is about to rise. The exten- sion of the thigh takes place during the last phase of contact and ceases as soon as the foot has left the ground to accomplish a new step. The muscles which execute it are more numerous and stronger than those which produce flexion ; a fact not to be wondered at, since these POSTERIOR MEMBER. 239 muscles have to displace the body-weight as well as to overcome the inertia, while, in the second case, they only raise the member and pro- ject it forward. The energy and the extent of their contraction will determine the intensity and amplitude of the femoral force which, in concert with the stifle and the hock, communicates to the trunk the initial impulsion, the action, as it is customary to say. Direction. The direction of the thigh cannot be suitably- de- scribed unless we understand well the signification which it is neces- sary to accord to this word. In animal mechanics, osseous segments have an axis of form which is not always their axis of movement. The latter being defined as the imaginary line which connects the two probable centres of movement, it is clear that it will differ from the axis of form whenever the articular surfaces are situated in front, behind, without, or within the axis of the latter. This has already been noticed in the case of the humerus, and is evident here again in the consideration of the femur. The axis of form of this bone follows almost exactly the direction of a line connecting the trochanter with the fossa which exists between the trochlea and the external condyle ; the axis of movement, on the contrary, joins the centre of the coxo-femoral to the centre of the femoro-tibial articulation, and crosses the first by reason of the fact that the head of the femur occupies the internal side of this bone instead of being situated directly at its superior extremity. In spite of the difficulties which, in the living animal, hinder the determina- tion of this fact, we may obtain the result in an approximate manner by seeking the two points indicative of the two aforesaid articular centres ; these are, on the one part, the concavity of the trochanter, and, on the other, the middle of the length of the external femoro-tibial ligament. The line joining these two points will constitute the axis of movement of the femur. In many subjects, the horse being supposed to be in equilibrium, it is almost vertical ; in others, it falls to a slight extent obliquely forward and downward ; finally, there are some in which it is oblique in an inverse sense, that is to say, downward and backward. The direction of the thigh should satisfy the four principal require- ments which follow : 1st. Give to the coxo-femoral angle, already reduced by the hori- zontal direction of the croup, a sufficiently wide opening. 2d. Permit of an extensive separation of the branches of the femoro-tibial angle, while allowing, at the same time, a feeble obliquity of the leg. 3d. Not alter the vertical axis, which implies the tangency of the hock to the vertical line falling from the point of the buttock. 4th. Finally, maintain the stifle in a certain state of separation from the median plane. We estimate, from our researches, that a mean inclination of 80 degrees fulfils all these desiderata in rapid motors. The obliquity in 240 THE EXTERIOR OF THE HORSE. the slow draught-horse may be more accentuated, since the coxa is less horizontal, but this modification is rarely observed. Ordinarily, in these horses, the femur is straighter at the same time that the croup is slanting, which thus increases this angle instead of diminishing it, so as to place the inferior parts of the member in a less defective position in relation with the vertical axis. Examinations of instantaneous photographs teach us that the limit of extension of the crural segment is situated but slightly pos- terior to the vertical line passing through the centre of the coxo-femoral articulation. In principle, therefore, the thigh should not be too straight when the animal is normally at rest, that is to say, when the line of direc- tion of the femur becomes confounded with the vertical line which extends from the centre of suspension of the limb upon the trunk. (See Vertical Axes.) When it is thus (Fig. 72, AB), the degree of extension of the femur is necessarily limited, the animal lacks action, and is incapable of utilizing the advantages of a long croup. Besides, his vertical axis becomes vicious, and the hock and the foot carried too far backward, render him camped behind. As to the muscles, the gluteals, HA, the extensors of the leg, mn, and the ischio-tibial muscles, Go, are short ; the flexors, iH, alone are long. When the femur, on the contrary, is too oblique, as CD, it is the flexion that is unduly limited. The arc which the foot describes at each step is too short ; the member, stationed too much under the trunk, works upward, and loses a part of its extension power in raising the body instead of projecting it forward, whatever may be the greater length of the gluteal muscles, HC, of the ischio-tibials, Go", and the extensors of the leg, win" '. On the other hand, the degree of inclination of the thigh being capable of modifying the value of the coxo-femoral angle, it may be questioned whether, for velocity, the obliquity of the croup would not be capable of compensating the excess of obliquity of the crural seg- ment in such a manner as to leave to this angle the same opening and, consequently, the .same degree of play. This compensation, as we have seen above, is possible, but only within very narrow limits, because the orientation of the articular angle soon becomes defective ; its bisecting plane assumes too horizontal a direction. Here, as in the arm, the principle is : to a horizontal croup should correspond a straight thigh. On the other hand, if it be necessary that the femur should pre- POSTERIOR MEMBER. 241 serve a suitable and efficacious opening of the coxo-femoral joint, it is no less obligatory that it should give a proper direction, as well as a FIG. 72. wide opening, to the angle which it forms with the leg. Observation demonstrates, in fact, that the femoro-tibial angle always has a wider opening in rapid motors ; this is the factor which prevents the tibia from assuming an excessive inclination which would place it in a posi- tion disadvantageous to its movements of extension and flexion and its effectiveness in progression. We therefore believe that a somewhat oblique thigh fulfils all these diverse requirements. It is the kind of thigh which is best for long strides, extensive and effective propulsive movements, and a normal 16 242 THE EXTERIOR OF THE HORSE. relation with the vertical axis. This is very different from the classical teachings of a certain school, that all the superior segments of the members should incline at an angle of 45 degrees with the horizon ! Finally, one more point of excellence in the thigh consists in its being well away from the median plane towards its inferior extremity. The region of the stifle, of which we will soon speak, will not, in this case, be exposed, in rapid locomotion, to come in contact with the abdominal parietes. If this separation, however, be too marked, it will cause an outward deviation of the inferior parts of the limb. Many horses, close behind and outbow-footed, owe the faulty direction of their posterior extremities to this cause. (See Vertical Axes.) Length. The length of the thigh, it can be plainly seen, must be in close relation with the amplitude of the oscillations of which it is capable ; besides, it governs the degree of the displacements of the tibia. In our opinion, it should be computed from the coxo-femoral articulation to the inferior part of the stifle. But its variations mani- fest themselves principally at the level of its posterior border. They are usually characterized by different expressions. Thus, such a buttock is said to be long or well descended (Fig. 73), which constitutes for this FIG. 73. FIG. 74. region a beauty of the first order, and of which the English thorough- bred, especially, offers a remarkable example. When the thigh is deficient in length, it renders the buttock round and short (Fig. 74), a defect which may also be due to too small a femoro-tibial an^le. The buttock is also named salient when its point POSTERIOR MEMBER. 243 is prominent in a horse in good condition, which signifies an easy rotation of the coxae on the posterior members. Width and Thickness. The width of the thigh is measured by a horizontal line which crosses it underneath the coxo-femoral artic- ulation. Its thickness, on the contrary, is appreciated, from side to side, either by viewing the animal from behind or obliquely from in front. It is almost superfluous to dwell upon the importance of these two dimensions, which show the muscular development of the region and, consequently, the impulsive force of the hind extremities. A thigh lacking sufficient thickness is designated as sharp ; when this deficiency affects the whole tlxigh, and is accompanied, moreover, by a lack of width, the thigh is styled flat, lean, or is called a frog's thigh; among horsemen the animal himself is known by the name froggy, by reason of the striking weakness of his hind quarters. The beautiful muscularity of the thigh can be summarized in a word : the animal is well rumped and strong-limbed ; his buttock is well furnished ; his muscles are firm, dense, and elastic. Peculiar Markings. The external surface of the thighs often presents cauterization brands, practised for the purpose of dis- tinguishing subjects, of recognizing their breed, and of testifying of their purchase, or of any prizes they may have obtained. Up to a recent date, horses in the French arrny were marked upon the left thigh as follows : with a grenade, if used by riflemen ; a C, by the cuirassiers ; a D, by the dragoons ; an H, by the hussars ; an A, by the artillery ; a hunting- horn, by the chasseurs ; a cross, by the lancers ; a T and an E, for the transpor- tation horses, etc. This practice having sometimes occasioned extensive slough- ing of the integument and disfigured the animals, these marks were subsequently made upon the side of the neck, where they were more or less concealed by the mane. Ultimately the accidents to the operators, the pain occasioned by the branding, and the complications and the blemishes resulting therefrom led to the adoption of a much wiser method, the marking of the hoof, which is alone practised nowadays. \ Nevertheless, in spite of the numerous disadvantages of the hot- iron brand, some large corporations have thought it advisable to pre- serve it. The Paris General Omnibus Company's horses are all marked with a number upon the left side of the neck ; those of the Paris " Petites Voitures" (or light-stage) Company, on the contrary, are marked on the hoof. There are cases in which one of the thighs bears likewise peculiar markings. Sometimes we find a number, sometimes a date, and at other times various letters, very often a P on horses that have won prizes ; again, figures of a special form, as in 244 THE EXTERIOR OF THE HORSE. the case of many Russian, Hungarian, and Andalusian horses, or those of certain studs. Diseases and Blemishes. The diseases of the thigh and the buttock consist in general of wounds, abscesses, and blood tumors, which are the result of blows, knocks, falls, or other purely accidental causes. There is, nevertheless, an important one for which we should keep a sharp w*atch ; this is an inflammation of the lymphatic vessels on the flat of the thigh. An examination of the course of these vessels reveals a hard, cylindrical, sometimes bosselated, cord, painful or painless to the touch, and of variable volume, which goes right up to the inguinal lymphatic glands in the groin. This elongated tumor, known under the name of corded lymphatics, is very often the symptom of glanders-farcy, and, for this reason, its existence is an ugly symptom. In other cases this condition is the consequence of diseases of the foot or of the inferior regions of the member. Whatever its cause may be, its presence always demands a most searching examination of the part by those who propose purchasing the animal. Let us also indicate the varix and thrombosis of the superior part of .the saphena vein, comparatively insignificant though they be, and, finally, the more or less numerous wounds and cicatrices which are the result of the cuts of the whip applied to this region. The thigh is a favorite spot, even as the breast, the axilla, the ribs, the sides of the neck, etc., for the application of setons. Traces of these indicate that the horse has been affected with chronic diseases of the foot, such as grease, canker, etc., or that these issues have been employed as counter-irritants against grave alterations of the encephalon or the spinal cord. Not infrequently, either, the external surface of the thigh shows marks of cautery in the vicinity of the coxo- femoral articulation. These reveal former cases of lameness where the seat of the malady has remained unascertained and all other methods of treatment have proved ineffectual. Their presence demands a minute examination of all the inferior regions of the member, even of the hoof. Many are the chances of locating the true cause of the lameness in those parts. B. The Stifle. Situation; Limits; Anatomical Base. The stifle corre- sponds to the femoro-patellar articulation, and is comprised between the inferior extremity of the thigh and the superior part of the leg. Externally, its outline represents two rounded, unequal eminences, one above the other. The upper, more voluminous, and due to the anterior crural muscles, overhangs the lower, which is smaller, and is caused by the patella. Below the I latter there exists a slight depression corresponding to the patellar ligaments and 1 the patellar adipose cushion. Finally, the cutaneous fold, known under the name of fold of the stifle, extends from the superior prominence of which we have spoken to the surface of the flank in the direction of the hypochondriac region. The stifle, in relation to its conformation, offers neither special points nor defects for consideration. It is important, above all, that its essential parts can be distinctly outlined. Its distance from the POSTERIOR MEMBER. 245 ground is ordinarily equal to that of the elbow, in swift horses as well as in others, whatever may have been said to the contrary. Whilst the neatness of outline of this region is a quality to be desired, its direction should not escape a careful examination. With good reason, a stifle which lies close to the abdomen, and is slightly deviated outward, is preferred to one that is low, deviated inward, or even parallel to the, median plane. The first direction, indeed;~rndi- cates great length and a beautiful obliquity of the thigh and great ease in executing the movement of flexion of this segment. In the second case, the stifle is liable to strike the abdominal parietes, a drawback which must needs have a certain importance in the modification of the rapidity of the gait, confining as it does the forward displacement of the thigh, the more so as it often coincides with a femur which is short and not sufficiently oblique. Nevertheless, too great a separation of the stifles will be defective, in so far that it will surely superinduce an outward deviation of the inferior part of the members and render the animal outbow-footcd. We will return to this point a propos of the axes. Diseases and Blemishes. The stifle presents various affections which deserve our attention. They are : 1st. Synovial dilatations, a kind of thorough-pins, which appear in the form of a soft tunior, more developed internally than externally, at the level of the patellar ligaments. They manifest themselves by a round, sometimes lobulated, fluctuating enlargement of a variable volume. When the distention is of large dimensions, the synovial membrane is bulged out above the patella underneath the extremity of the crural triceps muscle, where it forms a more or less accentu- ated swelling. Its prognosis is then rather serious on account both of the diffi- culty which is experienced in obtaining its resolution and of the lameness of the horse. 2d. Exostoses, located on the anterior surface of the patella, and resulting most frequently from external violence. 3d. Superficial or else deep wounds, inflicted by knocks or blows. They have no gravity so long as the skin alone is involved ; but the immediate conse- quence of such causes maybe/rac^re of the patella, a rare accident, fortunately, for it incapacitates the animal for work for a long time and induces nearly always a permanent lameness. 4th. Displacements, called luxations of the patella, common in young horses, and vulgarly designated under the name of foal's cramp. This bone, according to some, is supposed to be thrown out of its cavity of reception, that is to say, altogether dislocated towards the outer side of its trochlea ; according to others, it is supported, or rather held, by the very salient eminence which is formed by the superior extremity of the internal lip of the femoral trochlea. 1 1 See, for more details, Bulletin de la Societe centrale de medecine veterinaire, seances du 11 Aout et du 27 Octobre, 1881. (MM. Bouley, Chuchu, Cagny, Nocard, Trasbot, Weber.) 246 THE EXTERIOR OF THE HORSE. The latter opinion is nowadays most generally accepted. Be this as it may, the accident occurs but once, or again its reproduction may be intermittent and frequent, the bone becoming alternately dislocated and reduced spontaneously at the end of a variable period. In either case a very intense lameness supervenes, the chief diagnostic character of which consists in the attitude of the member, which remains in a state of forced extension, and can only be carried forward by a very marked abductive movement. A horse in such a state is, of course, not in a condition to be sold, unless, however, the sale should be made during the interval of two displacements of the patella, as we have had occasion to observe several times. 5th. Traces of blisters and cauterization denote that the region has been treated for one of the diseases of which we have just spoken, principally synovial dilatations. C. The Leg. Situation; Limits; Anatomical Base. The leg is the in- termediate region between the thigh and the hock ; the stifle and the buttock are also its upper boundaries. Two bones form its resisting, osseous base : the tibia and the peroneus. The latter is so rudimentary in the horse that it is hardly of any account so far aa animal mechanics are concerned. The tibia, on the contrary, strong and pris- matic, is situated obliquely from above downward and from before backward under the femur, to which it is joined by a very movable articulation. Two groups of powerful muscles cover it in front, on the back, and on the outside. Its internal face alone is subcutaneous, and therefore more exposed to- traumatisms. The function of the anterior tibial muscles is the flexion of the canon and the extension of the phalanges upon each other and upon the meta- carpus. The role of the posterior tibial muscles is precisely the reverse : with the exception of one, the popliteus, they are all extensors of the metacarpus or flexors of the digital region. They are, in a great measure, concealed externally by the inferior extremity of the ischio-tibial muscles which cover them. Lastly, most of them become inflected over the back part of the hock, that is to say, the summit of the tibio-tarsal angle, and by this very fact help to prevent the closing of this angle when the member is standing still. External Form. The tibial muscles, like those of the antibrachial region, have this peculiarity, that above they are constituted by a fleshy body, and below they are continued by a shorter or a longer tendon, destined to transmit their action to the canon or to the phalanges. The result of this is that the region, considered as a whole, presents a somewhat pyramidal or conical form, wider above than below, and compressed from one side to the other. Four faces may be recognized on this region, two of which, the external and the internal, especially merit our attention. The external face, almost plane superiorly, and confounded with the most declivitous part of the thigh and the buttock, shows quite distinctly the outlines of the muscles that we have mentioned above. Inferiorly, there is a change in its appearance near the hock : the external tuberosity of the tibia may be discerned in front, the anterior border of the calcanetis behind, and between these two eminences a depression which is called the hollow of (he hock. It is POSTERIOR MEMBER. 247 limited in front by the tibial crest and behind by the tendon of the gastrocnemius and perforatus muscles (cord of the hock, incorrectly called the hamstring tendon), which is inserted on the summit of the calcaneus. The internal face, almost plane and subcutaneous, is traversed by the saphena vein, which is accompanied by the artery of the same name and several lymphatic vessels, voluminous but not visible in the normal state. The very lowest extremity of this face displays in relief the internal tuberosity of the tibia, as well as the corresponding portion of the tendo Achillis, and, between these two, the concavity already indicated under the name hollow of the hock. Movements. The leg, owing to its mode of articulation with the thigh, is the seat of two principal movements, flexion and extension. During the former, the leg is carried upward and backward ; the femoro-tibial angle is closed in proportion to the length of the flexor muscles. Flexion commences in the latter part of the phase of con- tact, and is completed a little after the raising up of the foot. It does not entail much fatigue on the agents which execute it, as they have only to overcome the weight of the member to be raised. As soon as the thigh has effected its forward movement, the leg rapidly completes its own, and the amplitude of the arc of a circle thus described by its inferior extremity depends always (apart from the -length of the tibia itself) upon the degree of flexion which it effects and the distance at which the foot was raised above the ground. If the foot is not raised high enough at the moment when it is to come down on the ground, the hoof will be in contact again before the leg has had sufficient time to attain the maximum degree of extension of which it is capable. Indeed, it is evident that the length of the step is in direct ratio with that of the tibial extension. Length. The length of the leg is measured from the inferior part of the stifle to the fold of the hock. It is always equal to that of the forearm, and should be as extensively developed as possible in rapid motors. Upon it depends, indeed, the extent of the movements undergone by its inferior extremity, at the same time that it implies a proportional length of the muscles which belong to this region ; more- over, as these muscles are destined to move the canon, it follows that, for these two reasons, a long leg is indispensable to the velocity of the gait. If it be too short, the foot passes over less surface at each step ; the animal can only preserve his speed by dint of multiplying his move- ments and increasing his fatigue. It is needless to say that this con- formation offers nothing objectionable in slow motors, from which nothing more is expected than great muscular power. The length of the leg deserves, likewise, to be studied in relation 248 THE EXTERIOR OF THE HORSE. with that of the canon. In this connection, all authors are agreed that a short canon at the extremity of a long leg constitutes a great point. But why ? No one has explained it. Still, it is easy to account for it. The reasons are of the same nature as those which have been explained in connection with the forearm. Here, also, the metatarsus, at the time of contact, plays the part of a lever, at the superior extremity of which the weight of the body is de- composed into two secondary forces : the one, perpendicular to the canon, tending to carry the hock backward ; the other, parallel to this segment, showing the intensity with which the foot presses against the ground. The latter force, destroyed by the resistance of the soil, is for us void of interest. As to the former, it has the metatarsus for its lever-arm, while the extensors of this region are its antagonists. The shorter this arm will be, the less will be the muscular force required to counteract the tendency to flexion. Not only this, but, during the impulsion, the extension of the canon will equally be effected without any greater expenditure of force. A canon which is short -relatively to a long leg describes a less exten- sive arc of a circle, and is less heavy. These are additional reasons why the tibial muscles will have to contract with less intensity and to a smaller degree in order to produce the same effect. On the other hand, the metatarsus is covered only by tendons, in other words, by inert cords, simple agents of transmission. The tibia, on the contrary, is surrounded by the fleshy portion of the muscles, contractile organs, whose shortening gives the measure of the osseous displacements. Large dimensions should, therefore, be looked for in this region, which, it may be said, constitutes the active part of the segmented pendulum represented by the tibia and the metatarsus. The length of the canon not compensating the shortness of the leg, since its role in locomotion is absolutely passive, there is the best reason to select one that is short in relation with the leg when the object is to combine the best conditions for speed. This consideration in the draught-horse is of no importance. Width. The width of the leg is recognized at its superior extremity from before backward, and at the level of the enlarged portion of the extensors. It is always somewhat inferior to that of the fore- arm. It indicates the development of the muscles in this zone, and we know that the volume, density, and compactness of the muscles are, in the superior sections of the members, qualities of the first order. A horse with a leg thus muscled is called strong-limbed ; the calf of POSTERIOR MEMBER. 249 the leg is well outlined and powerful. In the opposite conformation, the leg is lean, flat, or frog-like, from analogy with that of the familiar batrachian. That is a grave defect, particularly in the draught-horse. The leg should also be wide in the vicinity of the tarsus. The calcanean cord must be distinctly separated from the tibia, for then the probabilities are that this separation is due to the length of the cal- caneum, that arm of the lever of the muscles which producer the impulsion, the extension of the hock. Nevertheless, let no error be committed here ; the separation in question may depend upon another factor : a more or less accentuated inclination of the tibia upon the canon. It is evident, from the mere examination of the diagrams of Fig. 75, representing two tibiaB, OM and ON, differently inclined upon their respective canons, that the wider leg is also the more inclined of the two, OM, although its calcanean lever, Q.C, may be absolutely of the same length as that, OD, of the straight leg, ON. FIG. 75, It is therefore requisite, at all times, to take into consideration the direction of the tibia in estimating the value of the width of the inferior part of the tibial region. Thickness. In order to estimate properly the muscular devel- opment of this region, it is necessary to consider its thickness, in other words, its transverse diameter. This can be appreciated by examining the horse obliquely from in front, or by viewing it from 250 THE EXTERIOR OF THE HORSE. before or from behind. The reliefs of the anterior muscles in either of these positions should be plainly marked and strongly convex out- wardj When the leg possesses but little thickness, it then lacks force, and is qualified thin, lean, flat, as we have seen above. Direction. The direction of the leg is as important a qualifica- tion with regard to the development of force as to the production of speed, for it favors the muscular action and facilitates the play of the articular angles, according to its obliquity. It is measured by a line joining two points situated the one above, the other below, the two external tibial tuberosities, superior and inferior respectively. The direction of the leg, like that of the thigh, should fulfil two principal requirements : 1st. It should not alter the regularity of the vertical axis, which axis affects the vertically of the canon and the tangency of the hock to the vertical line which falls from the apex of the buttock. 2d. It should secure a large opening and the proper direction of the femoro-tibial and tibio-tarsal angles. A mean inclination of 65 to 70 degrees, according to our researches, fulfils very well these conditions in swift horses. Indeed, instantane- ous photographs demonstrate that the limit of extension of the tibial section is situated very nearly on the vertical line which passes through the centre of the coxo-femoral joint. Remembering this disposition, as well as the fact that the femur is capable, during flexion, of surpassing posteriorly the vertical line through its centre of movement, it is only natural that the obliquity of the tibia should be more marked than that of the femur. When the leg is too straight, which is rare, its degree of extension is necessarily limited, and the step is short, whatever may be the length of the thigh ; the foot, being too far forward, causes the horse to be under himself behind. When it is too oblique, the flexion, on the con- trary, is reduced, and the hock, being carried too far backward, pro- duces the opposite defect, and the animal is said to camp behind. In speaking thus, we have supposed the direction of the femur and the metatarsus to be invariable, for it will be understood that the former of these segments, by modifying its inclination, might re-establish the normal axis of the limb. But given a proper obliquity of the femur, and, besides, the vertical direction of the canon as necessary, the posi- tion of the tibia has a direct influence upon the axes and the degree of aperture of the femoro-tibial and tibio-tarsal angles. Should it become more vertical, it widens the angles, lengthens the member, raises the trunk, diminishes the stability of the equilibrium, and POSTERIOR MEMBER. 251 favors speed ; should it become more inclined, it closes the angles, shortens the member, draws the body down to the ground, and favors the muscular insertions and the production of force. It is easy to understand that the more the tibia is inclined on the femur the more perpendicular is the insertion of the muscles upon their lever-arm and the more effective are their contractions. These two segments are never so oblique upon each other as to form a Bright angle, even when the member is in station. Although normally very obtuse, the more closed the femoro-tibial angle is the more favorably is it disposed for all the manifestations of force. It renders the buttock shorter without preventing it from being strongly muscled ; it diminishes the height of the animal without interfering with an increase of its bulk. Besides, is not this the form which this angle assumes when the draught-horse is called upon to move his load and to display great force ? Does he not incline the croup, the thigh, the leg, and the canon, close all the angles, bring the body to the ground, correct the muscular insertions, and, in a word, adapt his locomotory apparatus to the new conditions which are imposed on him ? In the rapid motor, the angle of the stifle should offer a greater amplitude. If, indeed, on the one hand we should seek in the abdomi- nal limb for a certain horizontally of the croup with a view of aug- menting the power and extent of the contraction of the muscles, the case is quite different with the inferior segments, the femur, tibia, and canon, which require but little obliquity to move one upon the other with a great amplitude when the foot is raised from the ground. It is for this reason that the femoro-tibial angle is much more open in the running-horse than in any other. A tibia excessively inclined in relation with the femur would not reach its limit of extension quickly enough ; too much time would be taken up, and the extension would not be terminated before the foot had touched the ground again. We have seen in discussing the thigh that the femoro-tibial angle is about 145 to 150 degrees in horses endowed with speed. This is a quality which we have recognized in the best running-horses, and which we will give only as a simple datum on which our judgment can be based, for this angle varies according to the type of the horse examined. In order to subserve speed, it is necessary, besides, that the tibio- tarsal angle be very wide, another condition which implies a small inclination of the direction of the leg. The canon can then be more strongly flexed, pass over more space, and take a long stride, particu- larly if the tibia be long and well muscled. Moreover, when the foot gets on to the ground again, the extension of the hock is at its full on 252 THE EXTERIOR OF THE HORSE. account. of the degree of closing which its angle has attained, and also because the extensor muscles of the canon are in a more favorable position to contract with intensity. A small tibio-tarsal angle depends upon one of two causes : an excessive obliquity either of the canon or of the tibia. In the first case, a portion of the force is expended in raising the trunk upward instead of propelling it forward. In the second case, the tibia, being too much inclined and too much directed backward, cannot execute its movements upon the femur with sufficient freedom, and limits the gracefulness and velocity of the locomotion. The tibio-tarsal angle, according to our measurements, oscillates about 156 to 160 degrees in the most beautifully constructed running- horses. It is never 136 degrees, as affirmed by the partisans of the theory of the parallelism of the segments, not even in the draught- horse, in which the angle is smaller, and in which, in truth, its exami- nation is of no importance. In this respect our observations are absolutely in accord with those of our colleague, M. Laulanie". Diseases and Blemishes. The diseases of this region, few as they are, are nevertheless capable of presenting characters of exceptional gravity. We will cite : 1st. "Wounds caused by kicks from other horses, received during work, out- door exercise, or in the stable. These wounds generally appear on the internal and the anterior faces of the tibia. They are less grave upon the external surface, because here the bone, protected by the muscles, is less predisposed to fractures. The intense lameness which accompanies these injuries usually prevents the animal from working or being presentable for sale. 2d. Osseous tumors, of about the size of a hen's egg, sometimes observed on the internal faces of the two tibiae, deserve the greatest consideration on the part of the buyer. Although their presence may be related to a simple external violence, yet they are often the sign of a veritable callus, that is to say, of the work of consolidation which has taken place at the point where the bone has been fractured in consequence of more or less intense traumatisms. Experience has demonstrated that incomplete fractures of the bone, imperfectly consolidated, may be rendered complete under the influence of muscular contraction alone. It is advisable, therefore, to defer the purchase of a horse which presents this blemish. 3d. Lastly, let us mention the lameness due to rupture of the tendon of the flexor of the metatarsus. This tendon, an integrant part of the muscle in question, extends from the inferior and external extremity of the femur to the supero-anterior extremity of the canon ; it plays a most important mechanical role, in so far as it establishes an intimate connection between the movements of the metatarsus and those of the thigh. This tendinous cord, under the influence of the energetic efforts made by the animals to free themselves from their bonds when placed under such restraint as is used by the blacksmith in shoeing a vicious POSTERIOR MEMBER. 253 subject, or when their limbs get entangled in the traces, when they are down on the ground, or again under the influence of a forcible gliding backward of the foot, etc., may not withstand the strain and may become ruptured. The simul- taneousness which at first existed between the movements of the two above-named segments at once disappears. The flexion of the canon is no more synchronous with that of the thigh ; the former sometimes remains pendulous or swings back- ward, and the tendo Achillis (cord of the hock) becomes relaxed and thrown into folds when the animal walks. As to the position of the limb in station, it is normal. This lameness, which must not be mistaken for a symptom of fracture of the tibia, in spite of its appearance, is ordinarily not serious ; it simply incapacitates the animal for his work for six or seven weeks. 4th. We need only mention, in terminating, the excoriations which are rather frequent upon the legs of kicking horses. They are common on the internal face in those subjects that struggle and kick to disengage themselves when the members have been displaced over the shaft or the pole of the vehicle or the traces of the harness. The presence of these wounds, or their traces on the skin, should be a warning to the intending purchaser of some bad and vicious disposition in the animal which is oifered to him. D The Hock. Situation ; Limits ; Anatomical Base. The hock, in the horse, is analogous to the knee. It corresponds to the tibio-tarso- metatarsal articulations, supports the bones of the leg, and forms the centre of the chief movements of the foot. Functionally, it is, more than any other, a region of dispersion of concussion as well as of propulsion. It is upon this region that the efforts of the extensor muscles which propel the body are concentrated ; it is on this point that the reactions of locomotion bear at the moment when the body, moving with great velocity, and projected forward, strikes the ground ; finally, this is the region on which, in the act of rearing, all the weight of the body presses down with such great force. Under these different aspects its study is full of interest, as much in relation to animal mechanics as to that of pathology. Let us examine with some detail the parts which compose it. The Bones. The tarsus of the horse is composed of six small bones, some- times seven, from a want of fusion of the median and small cuneiforms in one of them. Among these bones there are two whose volume and function are quite peculiar; these are the astragalus and the calcaneus. The first presents a very movable articular trochlea, or pulley, which is opposed to the inferior extremity of the tibia ; the second, more salient and elongated, is situated behind the preceding, continues, by its direction, the canon, and forms a powerful arm of a lever for the extensor muscles of the metatarsus. Underneath these two principal bones are found the four othero, flattened from above downward, with numerous facets. They are very solidly united to the 254 THE EXTERIOR OF THE HORSE. calcaneus and the astragalus, the three pieces of the metatarsus, and play the role of dispersing agents for the weight of the body in movement. Ligaments. The bones of which we have spoken are joined in a most intimate manner to the adjoining structures, the tibia and the metatarsus, by capsular and funicular ligaments, which allow perfect freedom in the tibio-tarsal hinge. Among these ligaments, two lateral, external and internal, unite the external and the internal tuberosities of the tibia to the head of the corresponding rudi- mentary metatarsal bones. They are elongated, rounded, unelastic, tortuous according to their length, and take successive attachments on the lateral surfaces of the bones which lie in their course. Two capsular ligaments of unequal resistance protect the tarsus in front and behind. The anterior, somewhat thin and stronger outwardly, extends from the anterior edge of the inferior articular surface of the tibia to the surface of the tarsal bones and the canon. It protects the synovial membrane in front. The posterior affects a general analogous disposition as to its attachments, but it is thin and membranous in its superior part in order to yield easily to movements of flexion, whilst in its centre and inferiorly it is reinforced by a plate of fibro- cartilage, which serves as a gliding surface for the tendon of the deep flexor of the phalanges. It keeps in position the articular synovial membrane behind. Articular Synovial Membranes. Of the five tarsal articulations, only one is interesting from an external point of view. This is the tibio-astragaloid, which is lined by a special synovial membrane. Although this membrane is firmly maintained on the sides by the lateral ligaments, and in front and behind by the capsular ligaments described above, nevertheless, it presents certain weak spots which may possibly yield under the influence of the interarticular pressure from an excess of synovial secretion. These spots are three in number : the one antero-internal, where the ligament is not protected by the anterior tibial muscles, the other two poste- rior, and situated above the reinforcing fibro-carti- lage of the posterior ligament. Pressure applied to any one of these swellings will cause the liquid to flow into the others, a fact which demonstrates con- clusively enough their intercommunication. Tendons and Tendinous Bursse. The ten- dons of the various muscles glide over the bones and the ligaments of the hock by means of synovial bursse, of which it is necessary to say a few words. In front and on the outside, the anterior capsu- lar ligament is maintained by the tendons of the anterior extensor of the phalanges and the flexor of the metatarsus, which is held by a fibrous aponeu- rosis in the bend of the hock ; their movements are effected through the intervention of the underlying connective tissue. On the outside is the tendon of the lateral ex- tensor of the phalanges, which a bursa of its own enables to glide through a duplicate of the external lateral ligament. On the inside we find the tendon of the oblique flexor of the phalanges (Fig. FIG. 76. POSTERIOR MEMBER. 255 76) having almost the same disposition along the internal lateral ligament, while below, supplied also with a special synovial bursa, the cunean tendon of the flexor metatarsi passes obliquely backward over the internal face of the hock ; this, when in a state of abnormal distention, is capable, according to Bouley, 1 of simulating a spavin by the enlargement that it forms under the skin at the very point where a spavin is located. Finally, at the back, the tarsus is transformed into a fibrous envelope known as the tarsal sheath. Its anterior wall is constituted by the posterior ligaments of the hock ; it is completed behind by an arch of fibrous tissue extending from the posterior border of the calcaneus to the inner side of the tarsal bones. It gives passage to the perforans tendon through the medium of a synovial membrane. The latter extends from the inferior fourth of the tibia downward to about the superior third of the canon. When this synovial membrane becomes dilated it forms two hernise superiorly in the hollow of the hock, one on the outer and the other on the inner side, posterior to the corresponding culs-de-sac of the tibio- astragaloid articulation. It is also prolonged downward along the flexor tendons in the shape of a tumor of variable size, sometimes simulating curb. The summit of the calcaneus also presents a little synovial gland, where the tendon of the gastrocnemius muscle is attached, to facilitate its gliding upon the aforesaid bones during extension and flexion of the metatarsus. This bursa, being very firmly sustained over its periphery, is not liable to become distended and form external dilatations. It is different, however, with the bursa which facilitates the play of the superficial flexor of the phalanges over the summit and along the posterior border of the calcaneus, and which almost entirely covers this surface. This tendon, after winding around that of the gastrocnemius, widens, becomes inflected over the head of the calcaneus, almost completely enveloping it, and is then continued in the region of the canon. Now, it is for a distance of about five centimetres along the perforatus tendon in front of the summit of the calcaneus that the enlargement manifests itself when, from excessive secretion of the synovial fluid, this membrane becomes distended. External Conformation. The hock is a centre of movement, whose perfect integrity is so important, as affecting the usefulness of the animal, that the eye should know and recognize its normal form in its least details. This region is divided into four faces: an anterior, a posterior, and two lateral. a. Anterior Face. The anterior face (Fig. 77, A) corresponds to the summit of the tibio-tarsal angle ; it has received the name of fold of the hock, and shows, on each side, the profile of the lateral faces. It presents, outwardly, above and behind, the summit, a, of the calcaneus ; below this, the external tuberosity of the tibia, b ; finally, below, the eminence, c, formed by the base of the calcaneus, the cuboid and the head of the external rudimentary metatarsal bone. On the inside, it offers the very prominent internal tuberosity of the tibia, d ; lower down, the internal tubercle of the astragalus, e ; finally, altogether below, the prominence of the head of the internal metacarpal bone, /; in its 1 H. Bouley, Nouveau Dictionnaire pratique, etc., t. x. p. 569. 256 THE EXTERIOR OF THE HORSE. middle is visible the tendons of the flexor metatarsi and of the anterior extensor of the phalanges, g ; inferiorly, the groove, h, of the pulley of the astragalus ; inwardly, the saphena vein crosses this face obliquely from above to below, i; finally, still on its internal part, the unsustained portion of the articular synovial membrane, k. b. Posterior Face. This face (Fig. 77, B] is angular and constituted from above downward : by the cord, I, and the point of the hock, a ; the posterior border, a', of the calcaneus and the perforatus tendon. But, viewed from behind, the hock also presents : the profiles of the lateral faces, b, n, c, and d, e, f (the same letters as in the preceding figure) ; the hollow of the hock, m. m, and the chestnut, o. c. External Face. This face is limited in front by a line which has, in its middle part, a summit, h (Fig. 77, C), corresponding to the astragaloid trochlea ; behind, the line, forming the profile of this same face, is very angular at the level of the summit of the calcaneus, a, at a point known, in external anatomy, under the name of the point of the hock. Between the latter and the canon are seen successively : the posterior border of the calcaneus, a' ; then the tendon, t ; above the point of the hock is detached, very prominently, the cord of the hock, I, in front of which is seen a deep depression, m, called the hollow of the hock. This face, for the remainder of its extent, is undulated in its middle by three superposed processes: the superior is formed by the infero-external FIG. 77. tuberosity of the tibia, b ; the middle one, more effaced, is constituted by the base of the calcaneus, n ; the inferior, c, corresponds to the cuboid and the head of the external rudimentary metatarsal bone. d. Internal Face. The internal face offers almost the same peculiarities as the external. It shows anteriorly the convexity due to the astragalus, h (Fig. 77, D) ; posteriorly, the point, a, the cord, I, and the hollow, m, of the hock ; in the centre and from above downward the infero-internal tuberosity of the tibia, d, the internal tubercle of the astragalus, e, and, finally, the large cuneiform and the head of the internal rudimentary metatarsal bone,/. But on this face are seen, besides : the muscular portion of the deep flexor of the phalanges, which POSTERIOR MEMBER. 257 is well outlined, p, over which are located numerous venous branches, r; the saphena vein, i ; the chestnut, o ; and, finally, the point, k, where the articular synovial is unsustained. Such is the conformation which the normal hock presents when it is examined on its four faces. We have insisted much upon this, in order that the beginner may not mistake for incipient blemishes nor- mal eminences and depressions which are only the indications of one of the primary qualities of this region, its neatness of outline. Examination of the Hock. The blemishes of the hock, as soon as they become apparent, modify at once the neatness of its lines, which cannot deceive the attentive and educated observer ; it is not the same, however, with the student. We would therefore advise the latter to examine the region with care in front, between the fore-legs, and behind, in order to determine the form of the profile of the lateral faces ; then to view it from the side, to see the profile of the anterior and the posterior faces. When he has acquired a certain skill, he can attempt a more complicated but more rapid examination, which is. called oblique or three-quarters, either in front or behind. The com- plexity and the greater rapidity of the oblique examination are readily understood, since, in such a case, the eye endeavors to appreciate, with the same glance, the two adjacent faces of the region. Some persons claim that it is ridiculous to examine the hock by viewing it from between the fore members ; others remark the same of those who, not contented with seeing with minuteness, insist, more- over, on feeling with their hands, the better to ascertain the facts. Such deference for the spectators' opinions would be very injudicious, and, moreover, a very bad example for beginners whose many-minded teachers are already so numerous. We are not aware that any one ever became possessed of science by intuition ; in order to know a thing a man must have given himself the trouble of learning it. Now, this book is especially prepared for the student, whom it is necessary to impress with this great truth, namely, that, in the pur- chase of horses, " he who does not open his eyes opens his purse wide !" Open your eyes wide, therefore, until you have acquired absolute cer- tainty concerning what you are examining, and by no means refrain from feeling with your fingers if needs be. We will never regret too much precaution in such a case, if we can thereby avoid committing an error ; and in any case the purchaser will not be the party who will complain of it. Whatever precautions may be employed, a careful examination of the hock always requires certain preparatory conditions in the animal. 17 258 THE EXTERIOR OF THE HORSE. He must stand in such a manner that each of the four members sup- ports its own share of the body-weight and lies in its natural axis. If this little detail is neglected, the eye will be deceived as to the true dimensions of the region and cannot compare the one side with the other, as we shall see in a future chapter. Movements. The hock is the seat of only two extensive move- ments, that of extension and that of flexion. The plane of these move- ments, on account of the obliquity of the astragaloid trochlea, is slightly oblique outward, a disposition which, coinciding with a certain obliquity of the femur, permits the member to be extended without being restrained by its contact with the abdominal parietes. There are, besides these principal movements, others, very limited, consisting of simple gliding of the contiguous bones, whose effect is to attenuate the locomotory reactions, and which are, in the case of the hock, an apparatus of dispersion analogous to that of the knee. When leaving the state of repose, the foot is always more abducted in flexion than in extension, and both are executed with the most per- fect regularity. When, however, the articulations of the member are diseased, whether those of the leg or those of the hock, as deduced from the observations of Rigot and from our own, flexion is sudden, jerking, exaggerated, and sometimes so extensive that the anterior face of the fetlock almost touches the parietes of the abdomen. This phe- nomenon constitutes string-halt or dry spavin ; but the hock offers no trace of external deformity. We will again revert to this on the subject of the gaits. Finally, when, at the moment of contact, the points of the calcanei are turned outward by a sort of rotation, of which the foot is the cen- tre, the horse is said to have rotating hocks. (See Gaits.) The Hock as a Centre of Amortissement and Impul- sion. This region is one of the most energetic centres of impul- sion in the posterior member. It is by its aid that the tibio-tarsal angle can suddenly open in order to project the body forward at the end of the phase of contact. The quantity of movement of the body, after being first dissemi- nated upon the bones and the ligaments of the coxo-femoral articulation, and secondly upon those of the femoro-tibial union, is then transmitted to the tibio-tarsal articulation, where, a certain portion having already been destroyed, it is again dispersed upon the tarsal bones and their ligaments. The combined action of the weight of the body and its velocity results in a diminution of the tibio-tarsal angle as well as of the other angles in the superior part of the member. In the hock, as POSTERIOR MEMBER. 259 elsewhere, the extensor muscles hinder this closing of the angle by acting in the manner of a lever of the second class, or that of force. The canon, which is a portion of the arm of this lever, takes its point of contact upon the soil by means of the foot, and receives the weight of the body upon the astragaloid pulley, while the power, represented by the gastrocnemius and the perforatus muscles, maintains the equi- librium of this weight by strong traction upon the extremity~bf the calcaneus. A fact here strikes the mind of whoever considers the nature of this power, that it has to overcome at every moment a resist- ance of more than 100 kilogrammes ! It is its relative feebleness ; it is the small volume of the fleshy body of the gastroc- nemius and the perforatus muscles, and even of the perforans, which can also sus- tain the tibio-tarsal angle ; it is the small volume of these agents, compared with the powerful muscles of the croup and the thigh, which Professor Lemoigne justly regards as a key to the rigidity of the member, a key without which all the other extensors would be deprived of their fulcrum or point of support. 1 It seems that there exists here an enormous contra- diction between the means at the disposal of the organism and the effects which it is to produce. This inconsistency is only apparent, and disappears as soon as we examine the mode of proceeding by which the extension of the hock is effected. By reason of the connections which exist between the femur and the calcaneus, through the interven- tion of the cord ab (Fig. 78), the opening of the femoro-tibial angle cannot take place without producing coincidently and in the same pro- portion the opening of the tibio-tarsal angle. As the opening of the former may depend upon the straightening of the femur or of the tibia, under the influence of their proper exten- sors, ef, cd, it follows that all muscular traction exerted on the summit, FIG. 78. A. Lemoigne, Note communiquee. 260 THE EXTERIOR OF THE HORSE. e, of the trochanter, or on the summit, c, of the patella, is communi- cated also in the same sense and with an equal intensity to the summit, a, of the calcaneus. It is thus that, in spite of their distance of separation, the exten- sors of the femur and of the tibia participate in an indirect manner in the extension of the canon, that is to say, in the maintenance of the tibio-tarsal angle, owing to the mechanical role of the cord of the hock. This remarkable synergy or correlation in the extension of the articular angles of the posterior limb explains the vigor, precision, and sudden- ness of the propulsive movements of this member during locomotion. It also accounts for the true action of the gastrocnemius, the perfor- atus, and part of the tibial aponeurosis, which thus become agents of transmission in common with the muscles of the croup, the stifle, and the leg, enormous muscles, acting together and simultaneously to over- come the inertia of the body and to propel the latter forward. Thus the organization of this cord responds admirably to the function which is allotted to it. Being composed of two voluminous tendons, that of the perforates and that of the gastrocnemius, twisted one upon the other, reinforced by a thick lamina of the tibial aponeu- rosis, and, finally, attached to the summit of the calcaneus, this cord acts, besides, almost perpendicularly to the extremity of one of the longest lever-arms in the economy. The tarsus, from the number of its bones, the smallness of their dimensions, the strength of their means of union, the tenuity of their movements, becomes finally the instrument which receives the force, transmits it, attenuates it, dis- perses and decomposes it without inconvenience to the living machine, on condition, however, that this base be constituted according to the mechanical principles which we are about to explain. Beauties. The hock, to be well formed, should be neatly outlined, lean, wide, thick, well opened, and well directed. Neatness of Outline. The hock is said to be neat and nicely cut out when it reproduces exactly the shape which we have described above. It is, in this case, exempt from blemishes, and its hollow is very pronounced. Leanness or Dryness. This region is, moreover, qualified lean or dry when all its normal elevations and depressions are well marked and covered by a fine, supple skin, adherent to the adjacent parts. The neatness of outline indicates the soundness of the pieces of the tarsal apparatus ; its leanness, on the contrary, implies the pureness of the breed, the fineness of the constitution, and the energy and excita- bility of the individual. In subjects of a lymphatic tern erament, as POSTERIOR MEMBER. 261 in those of the North of France and some of the districts of the West, the skin and the hairs are thick, the subcutaneous connective tissue abundant, and all the osseous reliefs more or less effaced. These animals frequently have & fat, full, doughy hock. We must not con- found this state with an absolutely blemished condition of the parts, for we should thereby frequently be liable to discard many excellent horses, in which, on account of the race, the climate, and the soil, it is impossible to obtain the dry hock which is usually observed in horses of meridional countries, above all in the finer races. Width. The width of the tarsus is an absolute quality, but in order to appreciate the same it is indispensable that the members be stationed in their normal axis. It is measured from the point to the fold of this region. It will be readily understood that, if the canon be placed well under the trunk, for example, this dimension will appear more considerable in consequence of the diminished obliquity of the calcaneus upon the tibia. It is precisely on account of this possible error, resulting very frequently from d defect in the vertical axis or a variable obliquity of the leg, that deception as to the width of the hock may arise, and the latter is not always far from it the ex- pression of the length of the calcaneus, even as many think. With H. Bouley, we should recommend the intending purchaser not to be satisfied with the one dimension indicated above. He should, more- over, appreciate the distance comprised between the cord and the ante- rior profile of the leg on the one part, and the perforate tendon and the anterior profile* of the canon on the other. In other words, it is absolutely necessary to ascertain the width of the hock above, in the middle, and below. If these three conditions are not fulfilled the region cannot be qualified wide, for it is eminently defective from the very disproportion of its parts. It is ordinarily at the inferior extremity, at the level of its base, that the region shows an abnormal narrowness, owing to which it is styled strangled. The tarsal bones of the lower row are, in this case, not in relation, in their development, with the dimensions of the astrag- alus, the tibia, and the calcaneus ; above all, with the last, which loses none of its power and acts, by this very reason, with so much more force upon the ligaments which unite it to the metatarsal lever, of which it really constitutes the superior extremity. Such a hock, there- fore, becomes blemished very soon, and should be rejected for very severe services expected from the saddle- or the draught-horse. When the region is deficient in width over its whole area, it is called slender, narrow. This is, we believe, a serious defect, although 262 THE EXTERIOR OF THE HORSE. there are some authors who excuse it, and even class this form of hock among the good conformations. We can only admit one thing or the other : either the width is an absolute beauty or it is a defect. If the former of these opinions be adopted, it is plain that the same qualities cannot be attributed to the narrow hock as to the wide hock, which is exactly the reverse. This is, nevertheless, what the authors of whom we speak have done, unknown to themselves, although the inconsistency of such a theory is at once apparent. The width of the 4 hock, in reality (we suppose it well directed and well opened), implies : 1. The separation of the calcanean cord, which, in its turn, depends upon both the volume of the posterior muscles and the length of the calcaneus (superior width). 2. The antero-posterior diameter of the tibio-astragaloid articula- tion and, here again, the length of the calcaneus (middle width). 3. Finally, the antero-posterior development of the inferior row of tarsal bones (inferior width), which is tantamount to saying that a wide hock commands a well-muscled leg ; a well-directed tarsal cord in relation to the arm of its lever, which is, in addition, powerful of itself on account of its great length ; large articular surfaces securing, consequently, much amplitude to the movements of extension and flexion ; finally, a solid union with the metatarsal column, whose width is evidently correlative. The slender, narrow hock presents a conformation precisely the opposite. It is, therefore, for inverse reasons, defective, which is indeed confirmed by observation. A strange sophism would be com- mitted, unknown to himself, by the man who would argue the useful- ness of so powerful a hock associated with a weak croup and bad loins. 1 The solidity of one region, it is true, can sometimes exaggerate the feebleness of another ; but this is not the case in the example under consideration. If such a croup or such loins transmit the impulsion badly, what will the impulsion be with a narrow hock? The two defects will be superadded to each other without any chance of compen- sation ! Thickness. The thickness of the hock is measured from one lateral face to another. It is appreciated by examining the region in front, behind, or obliquely, if one has more experience and a more prac- tised eye. Like the width, we must view it above, in the middle, and below, in order to assure ourselves that there is a proper correlation 1 Merche, Nouveau Trait des formes extrieures du cheval, p. 447. POSTERIOR MEMBER. 263 between the development of each of these secondary parts. The thick hock merits this name and is truly beautiful only on condition of its great transverse diameter at the level of the tibia, the astragalus, and the superior extremity of the canon. The tarsal thickness indicates that of the leg, of the canon, of the fetlock, and of the pastern. It bespeaks perfect steadiness and equi- librium in every part of the hind limb ; while its breadth has the entire command of the extent of the movements, the latter taking place backward and forward and vice versa. It is evident, however, that this thickness in the draught-horse, for example, should not be compared to that of the thoroughbred, two types essentially different. In the one, the bones are voluminous, short, and the muscles powerful ; in the other, the bones are long, relatively slender, and the muscles long. If each requires, with equal propriety, wide and thick articulations, absolute beauties applying to all services, still it is necessary that the proportions and the general harmony should not suffer thereby. Extent of the Tibio-tarsal Angle. As the hock is practically only one articulation, the summit of an angle, it is not useless to inquire if its degree of openness is capable of influencing the functions of the parts, and if this angle, once determined, can owe the separation of its branches to a greater or lesser inclination of the one or the other of them. In other terms, what is the value of the tibio-tarsal angle, and what is its orientation on the member to be in the most favorable attitude for the development of force or the display of velocity ? Most writers have endeavored to answer this question by advancing theoretical views insufficiently based on facts. Hence their writings contain numerous contradictions. We think we have been more logical in studying first very beautiful models, with a view of reasoning afterwards more easily in the particular cases which present neither an absolute beauty nor a veritable defect, and which are so often met in practice. Dismissing for a moment the obliquity of the leg, let us remark that the angle of the hock undergoes more or less the influence of the three metatarsal directions, as follows : a. The canon remains vertical. b. It is oblique forward and downward. c. It is oblique backward and downward. We will suppose, in each of these instances, the point of the hock tangent to a vertical line which would start from the point of the but- tock, as we remark it in the member with a normal axis. (See Axes.} a. The Canon, Vertical. The canon in this case is tangent 264 THE EXTERIOR OF THE HORSE. throughout its entire length to the previously-cited vertical axis. This position of the member is the most favorable to the proper exe- cution of its locomotory function, as we will verify a propos of the vertical axes. It belongs, besides, to all properly-conformed horses, whatever may be the service for which they are destined. The tibio-tarsal angle, under this premise, can be more or less open according to the situation of the tibia which constitutes its superior branch. Whence, consequently, there follow two secondary proposi- tions with regard to the direction of the latter segment. 1st. The Tibia, Straight. We will designate thus a tibia whose obliquity is little marked (about 65 to 70 degrees). The hock which corresponds to it is called straight; the angle which it forms is very open (Fig. 79). A similar conformation is favorable to velocity or speed, for it allows long strides, during which the calcaneus becomes more and more perpendicular to' the muscles that have to move it. Besides, the foot, on arriving on the ground, is more strongly flexed upon the leg, which gives the hock a more energetic and ex- tensive impulsion. Running-horses ordinarily have this region thus disposed; their tibio-tarsal angle is about 155 to 160 degrees, as we have already seen in treating of the leg. The observer is easily deceived as to the width of the straight hock on account of the direction which the calcaneus here affects. On that account it is necessary to observe the length of this bone during walking. But it is an error to believe that this hock, implying but little inclination of the tibia, necessarily violates the vertical axis by placing the limb more under the trunk. It suffices, to convince ourselves of the contrary, to observe the thoroughbred horses, which have in nearly all instances a marked opening of the tibio-tarsal angle, and to make measurements, as we have done, upon their articular angles ; it will then be verified that their axes are perfectly normal on account of the suitable direction of the croup and the thigh. The straight hock, which it seems should produce much fatigue to the animal from the little perpendicularity of its cord upon the cal- caneus, is precisely so disposed in order that the deficient muscular contraction may not interfere in a great measure. As H. Bouley 1 has FIG. 79. H. Bouley, loc. cit., p. 580. POSTERIOR MEMBER. 265 remarked, "when the pieces of a freshly-dissected hock are moved, it is easy to recognize that, towards the limits of its movement of extension and flexion, the angle opens and closes by a sort of spring- like action, which cannot be better compared than to that of the blade of a pocket-knife upon its handle. The articulation, being once opened, the two segments will remain in this state of extension by the very fact of the manner of coaptation of their surfaces of contact, and the intervention of a muscular force .to maintain them vertically is not at all necessary." The straight hock, finally, possesses this advantage from a point of view of speed, that it is usually associated with long posterior members capable of taking long steps. Supposing the lengths of the crural, tibial, and metatarsal segments to be equal, it is evident that their superposition, in a more or less vertical manner, will give a more con- siderable total height to the member than if these pieces are joined in a more oblique manner. Whence it follows that a horse having his bones thus articulated will have his locomotory apparatus more developed relatively to the body, and hence will be endowed with greater speed. 2d. The Tibia, Oblique. The first eifect of such a direction is the closing of the tibio-tarsal angle, allowing less freedom to the movements of flexion than if this angle were more open. Another effect is a more perpendicular insertion of the cord of the hock, which places the latter in the best conditions for the proper utilization of its force. The last result is a lessening of the total length of the posterior member and a proportionate diminution of the aptitude of the organism in relation to speed. Thus conformed, the animal is closer to his base of support ; the hock is strong, and its muscles well disposed ; but the step is shorter on account of the smallness of the tarsal angle and the diminished length of the member. All things being equal otherwise, the gait will be less rapid, unless it makes up by the repetition of its movements for the space and time lost at each stride, which will fatigue the ani- mal and wear him out more quickly ; but if the step lacks amplitude and the member length, the muscles may be more voluminous, the body developed, and the total mass considerable. The animal being then capable of the most energetic efforts at a very slow pace, the quantity of movement (mv) produced will not be less, because it will displace a greater weight with more feeble velocity. Poorly adapted for the turf, he will be excellent for traction, provided that his confor- mation has been modified in the sense which we have indicated. 266 THE EXTERIOR OF THE HORSE. The hock with a small angle, which we will call common, because it is ordinarily met in horses for light-draught and rapid heavy- draught services, is, in our opinion, more favorable to the production of force. Does this mean that the straight hock is defective for all laborious services, and that it is only observed in long-striding horses ? By no means. It is rather frequently seen in our heavy, lymphatic horses, which our measurements have proved ; it should not, in such cases, be considered as defective unless it at the same time lacks width, which is not rare, or unless its deficiency is not compensated by a mus- cular and powerful leg. b. The Canon, Oblique forward and downward. This conformation, in which the canon is deviated in advance of the verti- cal line falling from the point of the buttock, has caused the hock to be qualified elbowed or angular (Fig. 80). This hock, says H. Bouley, 1 "always appears wide in its superior part, because its angularness results in a separation of the calcaneus from the tibia and, consequently, places the calcanean cord at a greater distance from the latter bone ; whence a widening of the external surface. This bending of the region, besides, also has the effect of placing the arm of the calcanean lever in the most favor- able condition for the production of force. "But, by the side of these advantages, real disadvantages present themselves, which give ample reasons for considering this conformation as being defective. First, the column of sup- port below the tibia being situated obliquely, it results that the press- ure of the weight of the body, instead of being transmitted to the ground by the bones exclusively, as in the vertical position of this segment, causes a strain, proportionate to the degree of the obliquity, on the ligaments which unite the tarsus with the metatarsus as a whole, and imposes upon them an abnormal function. In addition, these ligaments, during locomotion, are subjected to all the greater strain, because the muscular force finds, in the direction of the cal- canean lever-arm, more favorable conditions for its development. These are two causes which fatigue the apparatus of the hock more and hasten its premature ruin. Experience bears witness to this FIG. 80. 1 H. Bouley, loc. cit., t. x. p. 579. POSTERIOR MEMBER. 267 effect. Nothing is more common than to witness, at the base of elbowed hocks, the development of osseous tumors, which are the expression of the excess of its function, to which such hocks are pre- disposed from the very fact of their defective conformation. We can understand that this defect will tend to become more exaggerated when the hock, instead of corresponding to the vertical through the buttock, is situated farther under the centre of gravity. Horses whose hocks are angular are often animals of superior quality so far as energy for work is concerned, and are, consequently, predisposed to ruin themselves so much more quickly, as the apparatus upon which they apply their force possesses less favorable conditions for resistance." The learned author of this quotation might have added that the angular hock, by drawing the inferior part of the member towards the centre of gravity, by causing an exaggerated closing of the tibio-tarsal angle and too great a stretch of the foot forward under the trunk, determines, besides, an overloading of the posterior members prejudicial to their functions. It augments the work of the extensor muscles of the metatarsus during station, diminishes the amplitude of the step by restraining the movement of flexion, and, finally, expends to no pur- pose a part of the effort of impulsion to elevate the trunk instead of carrying it directly forward. Such a hock should, for these reasons, be rejected in spite of its apparent width, for it is the result of an imperfection in the axis of the member which will soon ruin it. c. The Canon, Oblique downward and backward. This direction of the canon places the posterior member in the attitude which is called camping, and which approaches somewhat that of the animal when he urinates. We will have occasion to return to this in discussing the axes. Let us say, for the present, that it places the members in a very unfavorable condition to fulfil, with ease, their functions as columns of support and as agents of impulsion, relatively to the trunk. It removes them too far from the centre of gravity, transfers a corresponding portion of the body-Aveight upon the anterior members and the loins, and renders the impulsion more feeble and less extensive ; it predisposes to gliding backward, fatigues the animal more, leads to sway-backedness, etc. (See Axes.) We must not confound this conformation with that which is proper to a straight hock. The femoro-tibial and tibio-tarsal angles, in the latter case, are open, but the natural axis of the limb is preserved, while, in the horse camping behind (only from the hock down), the tibia remains very oblique, whilst it leaves the tibio-tarsal angle very 268 THE EXTERIOR OF THE HORSE. large and disturbs the normal axes. Whence it follows that this angle is badly disposed for the functions of its branches during locomotion, and even tends to resist the efforts intended to draw them towards each other during station. Its bisectrix, if prolonged to the ground, meets the latter at a point insufficiently distant from that where the hind feet effect their contact, and the consequence then is that the angle is quite as badly opened for the production of speed as for that of force. Direction of the Hock. The direction of the hock must be studied from two different points of view : in relation with the median plane of the body and in relation with the axis of the member. 1st. Direction Relative to the Median Plane. Relative to the median plane of the body, the hock can assume three situations, namely : It is parallel and thus well directed. It is deviated inward and qualified close or cow-hocked. Finally, it is deviated outward, which renders the horse open behind. In order to have its normal direction, the hock should be parallel to the median plane, for its branches are flexed and extended upon each other in a plane equally parallel, not to speak of the normal devi- ation which the inferior part of the member affects during flexion. In this case the impulsion given by the posterior limbs is transmitted, without lateral oscillations, to the spinal column, whose direction it follows, and there is no waste of force in the projection of the body. The play of the extremities is easy ; the feet are not predisposed to interfering ; their contact with the ground is uniform ; the gait is free, regular, brilliant, and the tarsal apparatus will withstand a prolonged service. When the hocks are close or crooked (Fig. 81), their points, when viewed from behind, converge, and the inferior part of the members is deviated outward. The horse is then designated cow-hocked, or close- hammed; his movements are without elegance, although the conforma- tion is often associated with very great qualities. If, on the contrary, the points of the hocks (Fig. 82) are diverging, the lower part of the member is turned inward ; the animal is open, or too open behind, in view of the great separation of the two calcanei. We will explain, when treating of the axes of the members, the dis- advantages of these defects, which give to such subjects the most ungraceful gaits imaginable. 2d. Direction Relative to the Axis of the Member. In POSTERIOR MEMBER. 269 order that the tarsal apparatus may fulfil its functions well, it is not enough that it should be in a plane parallel to the axis of the body, but it is also necessary that the median line of the member divide it into two very equal moieties. If this condition be not realized, the FIG. 81. FIG. 82. region of the hock is displaced inwardly or outwardly, and becomes the seat of irregularities in its contact more or less prejudicial to the integrity of the locomotory machine. When the hocks are strongly convex on their internal face from above to below, they are most ordinarily angular in front, and the animal is close behind. The deviation opposite to the latter, and common in horses too open behind, consists in a rather strongly-marked concavity of the whole of the internal surface of the member, in virtue of which the calcanei become very diverging, while the two hoofs, nearer each other than they should be, converge and even touch each other in the region of the toes. A horse offering this conformation could be called bow- legged, on account of its analogy to the aspect of the man whose legs are thus directed. In both forms the hock does not give the natural impulsion to the body, and the members move in a very ungraceful manner. (See Axes of Members.) Diseases and Blemishes. The alterations of which the hock may be the seat, says H. Bouley, 1 are numerous, varied, and often of extreme gravity. They may affect any of the constituent parts of H. Bouley, loc. cit., p. 586. 270 THE EXTERIOR OF THE HORSE. this complex apparatus : the bones, the synovial membranes, the liga- ments, the tendons and their sheaths, and, finally, the subcutaneous tissue. The skin itself is sometimes affected, but only in a mild degree, as compared with the intrinsic pieces of the region. The number and gravity of these lesions are readily explained by the important role of the hock in the function of locomotion. Following the method of H. Bouley, we will study them by passing from without to within. They exist, in fact, upon the skin, the con- nective tissue, the tendons and their bursae, the bones, and the tibio- tarsal articular synovial membrane. a. The Skin. The point of the hock is quite frequently the seat of denuda- tions and excoriations, whose presence should attract the attention. Such wounds, by reason of their locality, are often an index of the vicious character of the animal, or of his irritable disposition. They result from blows, kicks, kick- ing, and are particularly common in irritable mares which are continually uri- nating. They are sometimes followed by accidental white markings in subjects with dark-colored extremities ; at other times by cicatrices of a variable con- figuration, visible on the outside, covered by the surrounding hairs, or fraudulently hidden by a colored coating. Traces of cauterization, in points or in lines, which are seen on blem- ished hocks should induce one to ascertain whether the affection for which the cauterization has been employed has entirely disappeared, or whether the region is improved in a manner to permit of a better utilization of the animal. It is in the fold of this hock that the most serious cutaneous lesions are observed. They consist of transverse fissures, known under the vulgar name of sallenders, occasioned by external irritation, con- tinual friction, or the application of a vesicant. Pri- marily benign, sallenders soon becomes complicated in consequence of the irifcessant movements of the parts, and also other causes, such as the humidity, the eleva- tion of the temperature, uncleanness, etc. It then becomes a wound, rebellious to cicatrization, with thick, indurated borders, covered with scabs, and always very painful during the hot seasons. b. Connective Tissue. The subcutaneous con- nective tissue at the point of the hock, under the in- fluence of contusions and repeated frictions, becomes infiltrated with serum, and forms at the end of a cer- tain time a soft, fluctuating, sometimes oedematous, non-inflammatory tumor designated under the names FIG. 83. capped hock and capellet l (Fig. 83). Capped hock is nothing else but hygroma of the summit of the calcaneus. Its greatest inconvenience is the deformity of the point of the hock, but it occasions no lameness. It constitutes none the less quite a 1 " The first of these names is without doubt derived from the fact that the tumor has been compared to a small cap adorning the head of the calcaneus." (H. Bouley.) POSTERIOR MEMBER. 271 serious blemish in pleasure-horses, on account of the deformity which it produces and the tenacity with which it resists the means employed for its resolution. It must not be confounded with the purely accidental O3dema of this part in horses standing in the stable for a long time, which disappears promptly under the influence of exercise. c. Tendons and Tendinous Synovials. We will mention, in passing, the rupture of the tendinous portion of the flexor metatarsi, of which we have already spoken in the article on the leg, and which gives rise to a lameness of a special character. We will also name an accident, an exceptional one, indeed, luxation of the calcanean attachment of the perforatus. In the two known cases, the tendinous portion of this muscle had ruptured its insertion on this bone from a very violent effort of traction, was dislocated externally to the point of the hock, and produced so visible a deformity that the animal could not have been offered for sale. It is the same with the ossification of this calcanean cap, as well as of a portion of the tendon itself, which we have observed, on one occasion only, in an old horse that was sacrificed for dissection, and whose hock we deposited in the Department of Collections at the Alfort School. These lesions have no other interest than their rarity. A different case, how- ever, is that of the abnormal dilatations of the synovial sheaths which facilitate the gliding of the tendons in the region of the hock. These are, on the contrary, most common, always very grave (some of them at least), with regard to the de- preciation in the value of the animal. They are known under the generic name of tendinous hygroma or thorough-pin. The most serious among them is undoubtedly that of the tarsal sheath, which, for this reason, has received the name of tarsal or tendinous thorough-pin. It is characterized by subcutaneous tumors, which appear at the superior or at the inferior part of the hock, at the points where the synovial membrane has no support. The superior dilatation is situated in the hollow of the hock, immedi- ately in front of the tendo Achilla or cord, and along its course. More salient on the internal side, it is sometimes bilobed, and may reach the inferior fourth of the leg. When it is very voluminous, pressure exercised upon it will not force the liquid to the anterior face of the hock, because the tarsal sheath does not communicate with the articulation ; but such pressure, being transmitted to the swelling at the inferior part of the hock, renders them more apparent. These tumors, less developed than the preceding one, and less distinctly out- lined in consequence of the thickness of the walls of the sheath, follow the course of the flexor tendons to the superior third of the canon. " Tarsal thorough-pin," says H. Bouley, " is susceptible of acquiring enormous dimensions, particularly on the internal side. It has been seen to be enlarged in such proportions that the space between the two members was no longer suffi- cient for their normal movements, and the skin over its surface was excoriated from the constant friction against the opposite hock during the movements of locomotion." The synovial bursa which facilitates the gliding of the expansion of the perforatus upon the summit of the calcaneus is also capable of becoming dilated to an abnormal degree. Although very strongly attached here, it can yield to the pressure of the liquids from within, forming along the cord of the hock an 272 THE EXTERIOR OF THE HORSE. elongated, cylindrical tumor, ordinarily of a small volume, and about ten centi- metres in length. This is called calcanean hygroma. H. Bouley observed with justness that the synovial cul-de-sac which permits the gastrocnemius tendon to glide upon the summit of the calcaneus, during the movements of extensive flexion, is so powerfully supported by the expansion of the perforatus that it is absolutely impossible for it to dilate in the form of external enlargements. He adds, with equal accuracy, that this synovial cannot in any manner give rise to the tumor which we have studied above under the name of capped hock. Finally, it is also possible to meet hydropsy of the small bursa which facilir tates the gliding of the cunean tendon of the flexor of the metatarsus over the surface of the internal lateral ligament. It presents a small, soft, fluctuating tumor of the size of a large bean, situated in front of the point where the exos- tosis of a spavin usually forms and for which it is sometimes mistaken. This dilatation has received the name of cunean hygroma, on account of its location in relation with the tendinous branch under which it is developed. d. Articular Synovials. It is rather common to meet upon the astrag- aloid pulley and in the corresponding grooves of the tibia more or less deep multiple striae or fissures, perfectly regular, and all of them parallel to the lips of the astragalus. These strice of the articular surfaces are most common in old horses. They are, without doubt, due to some slow and obscure irritation of the tibio-tarsal joint, and correspond probably to a special irregularity of its move- ments ; but clinicians at present have not determined in a precise manner the external symptoms of this variety of lesions, which should consequently be investigated. (See Defects of the Gaits : String-halt.} The most serious alteration of the tibio-astragaloid articulation is consecutive to a hydropsy of its synovial membrane. The synovia, under the influence of an excessive functional activity on the part of this membrane, is secreted in larger quantity in the articular cavity, and, in the long run, exercises pressure from within which, little by little, dislocates the parietes of the articular cavity. But as the latter are not equally sustained everywhere, the places which offer the least resistance to the internal pressure are distended beyond their physiological limits and produce a hernia, by forming under the skin three tumors whose posi- tion is stationary, whose volume and tension alone change according to the intensity of the alteration. These three tumors constitute what is called articular thorough-pin of the hock. The first of these is located in the fold of the hock and a little to the internal side. It modifies the profile of the anterior face of this region by the presence of an abnormal curve, yielding, and always more tense to the finger when the member is on the ground. The other two articular dilatations are situated behind and above the lateral ligaments, between the tibia and the perforans tendon. They have a variable volume, which ranges from that of a walnut to that of a child's head; the internal is most frequently larger than the external, which is sometimes absent. The presence of one of these constantly coexists with that of the anterior swell- ing, and that is what we might expect, since all three are only diverticula of the same cavity. Pressure exercised upon one of them is communicated to the others. The synovial dilatations are, in general, less grave than the osseous tumors. POSTERIOR MEMBER. 273 They may for a long time remain compatible with the liberty of the movements. They (the articular especially) lame the animal only in cases of abundant hyper- secretion of synovia and excessive tension on the surrounding tissues. Their parietes, in long-standing cases, become thickened and calcined in places, restrain- ing greatly the tarsal movements. When the calcification is very extensive, it constitutes a false anchylosis of the articulation, which renders rapid locomotion absolutely impossible. e. The Bones. The osseous blemishes in the region of the hock have received different names. They are: curb, spavin, andjarde. 1st. Curb. Curb (Fig. 84, B, and Fig. 85, A) is a periostitis of the infero- internal tuberosity of the tibia, which is developed under the influence of external violence or excessive strain of the articulation. It is characterized by the forma- tion of osseous layers, which are disposed in regular strata upon the tibial tuber- osity, over the surface covered by the attachment of the internal lateral ligament. FIG. 84. FIG. 85. This formation offers a longitudinal groove in which the tendon of the oblique flexor of the phalanges glides and manifests itself externally by a curve, more pronounced than in a normal state, when this face is viewed from in front, behind, or obliquely. At the beginning, it is often difficult of recognition from its feeble dimensions, which render the comparison of the two hocks necessary. Unless they are both blemished, it is generally easy to determine the presence of such a neoplasm, for it is exceptional that the two enlargements should be absolutely identical in relation to their form and volume. Curb only occasions, lameness during its formation ; when it is once developed, the lameness disappears. Nevertheless, there are some which from the volume which they attajn cover up the margin of the tibial articular surfaces and interfere, more or less, with the freedom of the movements ; in such cases they are all the more grave, as they are rebellious to all means of treatment. 2d. Spavin. The term spavin should be reserved to denote a periostitis at the lower and internal part of the hock (Fig. 84 and Fig. 86, A). It involves 18 274 THE EXTERIOR OF THE HORSE. FIG. 86. most usually certain bones of the tarsus and of the metatarsus covered by the expansion of the inferior extremity of the internal lateral ligament of the ar- ticulation, that is to say, the head of the rudimentary metatarsal bone, a small portion of the principal metatarsal, the cuneiforms, the scaphoid, and even the base of the astragalus. Frequently, however, it is much more circumscribed, which has led H. Bouley to specify as metatarsal, or low, the spavin which is situated at the upper extismity of the canon, and as tarso- metatarsal, or high, that V 7 hich affects the bones of the tarsus as well as those of the metatarsus. The first is manifested externally as an exaggeration of the eminence formed by the head of the internal splint bone, or, again, when it is more anterior, by the greater vol- ume of the tuberosity of insertion of the flexor muscle of the metatarsus. Sometimes it is complicated by a splint on the canon, in consequence of the abnormal ossification of the in- lerosseous ligament which unites the rudimentary to the principal metatarsal bone. Whatever may be its exact seat and its volume, which are susceptible to variation, metafarsal spavin ordinarily occasions only a temporary lameness, which ceases, in most instances, after a certain lapse of time, when the work of ossification is completed. As to tarso-metatarsal spavin, its gravity is very different and its frequency much greater. It constitutes, in fact, a kind of exostosis which solders the inferior bones of the tarsus to one another and to the metatarsus. It is at first limited to the periphery of the articular margins, but progressively invades the articular surfaces themselves. The latter complication, whose evil effects are easily under- stood, in one word, true anchylosis, does not always exist, even in the case of very voluminous exostoses. We have examined the articular surfaces in a number of instances in old horses, and found them still intact. Such a lesion does not, as can be perceived, completely annihilate the movements of the tarsal articulations, and, consequently, lessens the gravity of the prognosis which may have been deduced from it. Bone spavin, at the beginning of its formation, and before the appearance of the external tumor, determines a lameness, generally very intense, upon the nature of which it is almost impossible to decide with certainty. The lame- ness which follows has no pathognomonic character, even when it is accompa- nied by the jerk of string-halt. It is only at the end of a certain time that the exostosis is manifested in profile upon the internal side of the hock. Its volume and its seat are, in such cases, very variable. Som3times scarcely distinct, some- times very well defined, it projects inward, forwa/d, or backward from the ar- ticulation. In rather frequent cases the lameness at this period diminishes in intensity or disappears entirely ; but in most instances it persists and remains in relation with the extent of the tumor. Its characteristics are no longer the same ; the animal suffers less pain and the limp seems to be due more to the mechanical difficulties which the tarsal bones experience in their displacements. However it may be, it is apparent that the gravity of the prognosis varies with the nature of the articular lesions, the obstacles offered to locomotion, and the persistence and tenacity of the rational symptoms to which the blemish is heir. POSTERIOR MEMBER. 275 FIG. 87. 3d. Jarde. 1 Jarde (Fig. 87) is not, as every one wrongly believes, an osse- ous tumor, reproducing identically, upon the external side of the hock, the enlargement which a spavin forms on the internal side of the same region. It is simply a more or less extensive periostitis of the head of the external rudimentary metatarsal bone. This lesion is very often complicated by a splint, as in the case which we represent (Figs. 88 and 89) ; at other times, and this is perhaps the most frequent circumstance, nothing is found but a tumor developed at the superior and external side of the canon, that is to say, a simple splint. This is at least the opinion which we have acquired as the result of our re- searches for a period of observation extending over more than forty years, in conditions altogether exceptional in so far as the abundance of the specimens studied was concerned. Jarde is never situated at the same height as spavin ; it is always lower, which already implies that the external tarsal bones are not the seat of it. Besides, it remains con- fined outwardly or posteriorly, and does not extend forward as spavin does ; finally, it is rather inclined to descend along the rudimentary metatarsal than to ascend upon the cuboid or the base of the calcaneus, additional reasons which mili- tate in favor of its metatarsal origin. It should, therefore, neither in location, lesions, nor gravity, be considered as the homologue of spavin. We also sometimes meet, on the outer side of the hock, a tumor localized on the base of the calcaneus, the scaphoid, the cuboid, and the head of the external metatarsal bone, a tumor sufficiently circumscribed to merit a special name other than that of osteophyte, of which we shall speak farther on. (It could be called external spavin.} In 1852, M. Gillet 2 represented the true jarcle with great exactness, although, by a singular deference for the erroneous opinions of his predecessors and his contemporaries, he would not abide by his own observations alone. His draw- ing, altogether similar to our own (Figs. 88 and 89), differed, for good reasons, from all the other more or less fantastic representations which have been made of the blemish in question. We will add that it is very rare to meet lesions of this nature, and we are certain not to be contradicted upon this point by those who have taken the trouble to search for them. The anatomical facts explain why the periostitis of which we speak can really only take its origin upon the head of the external splint bone and not otherwise. It is necessary first to recall that exostoses resulting from usage appear only at points of insertion of the large articular ligaments. It is at these points that tractions and irritations are conveyed to the periosteum and inflame it. The irritation, spreading little by little, invades ultimately all the bony sur- faces covered by these ligaments. It is according to this process that curb, spavin, and exostoses of the bodies of the vertebrae are produced ; this same pro- cess we shall find again as the primary factor in the formation of splints or 1 This is the "curb" of English authors. 2 Gillet, Des Tares osseuses des membres du cheval, in Recueil de memoires et observations sur Phygiene et la mgdecine v6terinaires militaires, t. iv. p. 317, chez Dumaine, Paris, 1852. 276 THE EXTERIOR OF THE HORSE. exostoses of the canon. The formation of a jarde is no exception to this prin- ciple. FIG. 88. Jarde upon the dissected hock. It commences at the head of the external metatarsal bone (Fig. 90), that is to say, at the inferior insertion of the powerful calcaneo-metatarsal ligament, b, so much more exposed to traction on its component fibres as the efforts which POSTERIOR MEMBER. 277 produce it are exerted at the extremity of a calcaneus longer and more oblique upon the tibia. Hence it has always been considered as coexistent with angular FIG. 89. Jarde upon the macerated hock. hocks. The tumor, once formed, has no tendency to ascend ; it remains localized at the place which we have just indicated, or, perhaps, is complicated by a splint upon the tract of the interosseous ligament, which unites the principal meta- tarsal to the corresponding rudimentary bone. With regard to its seat, it may 278 THE EXTERIOR OF THE HORSE. be defined as a periostitis of the calcaneo-metatarsal ligament, b (Fig. 90), and the external tibio-tarsal, a (Fig. 91), and spavin as that of the astragalo-meta- tarsal, b (Fig. 91), and the internal tibio-tarsal, a (Fig. 90), ligaments. FIG. 90. Dissected hock viewed inwardly and posteriorly. FIG. 91. Dissected hock viewed inwardly and in front. Whatever may be its situation, it occasions a very characteristic deformity of the profile of the base of the hock. The line which passes from the summit of the calcaneus to the fetlock, instead of being perfectly straight, describes, on the contrary, a curve with the convexity posterior, at the level of the head of the splint bone and most frequently a little below. The enlargement is also per- ceived upon the hock viewed from behind or obliquely. When the jarde assumes the form of a splint, it sometimes elevates the suspensory ligament of the fetlock by developing in the posterior gutter, which serves as a cavity of reception for the latter. In this case it is the line of the tendon which loses its rectitude and becomes more or less convex behind. Before leaving this subject, we should warn our readers against a tendency which is quite general among horsemen, particularly in the army: it is the mania of jardes, if we may use such an expression. Many jardes exist often only in the imagination of those who speak of it, and who, to a certain degree, cannot inspect a horse without seeing this lesion. The head of the external metatarsal bone, in our opinion, has not always the same configuration ; it is sometimes very angular, and may, in this case, alter externally the posterior profile of the tarsus, above all, if the hock is cow-hocked, without justifying thereby a conclusion of the existence of a blemish, because the structures still are and will remain perfectly normal. POSTERIOR MEMBER. 279 A jarde is far from offering the same gravity as spavin. This is simply due to the fact that it never terminates in anchylosis of the inferior tarsal articula- tions ; the latter remain absolutely intact. The lameness which it determines, when the work of ossification has been completed, depends upon the want of freedom experienced by the small metatarsal arthrodia or the compression of the suspensory ligament of the fetlock and the flexor tendons. Osteophytes. The hock does not always present so clear a delimitation of its osseous blemishes ; in old horses it is quite frequently the seat of dissemi- nated bony deposits whose point of origin may be in the thickness of the ante- rior capsular ligaments, that of the lateral ligaments, or again in that of the articular and tendinous synovial membranes. This condition, as we have seen, is the ultimate complication of synovial dilatations, and, consequently, is nothing remarkable. The normal profiles of the hock, in such instances, are completely changed. At the level of these osseous tumors the region presents more or less voluminous, hard, and irregular reliefs, which have a great tendency to join and eventually encircle the tarsal apparatus. These are always conclusive evidence of ruin and of usage driven to its utmost limits. E. The Chestnut. The chestnut, o (Fig. 77, B and D), in the posterior member, is situated on the inferior part of the internal surface of the hock. It responds anatomically to the small cuneiform, and is sometimes wanting. Huzard the elder has mentioned its absence, and we have also verified it in several instances. In such a case the description of the horse should mention the fact. As in the anterior member, its area and volume vary in a great measure according to the race ; it has, besides, nothing of special interest. (The chestnut, anatomically, is the rudiment of the hoof of the fifth digit or thumb, which it represents. Its absence is most fre- quently noticed in meridional horses, probably the descendants of the African horse, which, of all the equine races, is the most closely related to the ass. It is smaller in well-bred horses. Harger.) F. The Canon and the Tendons. Situation; Limits; Anatomical Base. The canon is the region of the members which extends vertically from the knee or the hock to the fetlock. Its anatomical base consists of the three metatarsal or metacarpal bones, the tendons of the different motor muscles of the phalanges, and a very strong liga- ment, known, on account of its functions, under the name of the suspensory ligament of the fetlock. 280 THE EXTERIOR OF THE HORSE. Of these three bones, one, the principal metatarsal or metacarpal, is much more developed than the other two, which are altogether rudimentary. The latter (Fig. 92) are united to the sides of the principal bone by means of a very resist- ing interosseous ligament which ossifies with age, save at its two extremities. FIG. 93. The superior part, or the head of these small styloid bones, is articulated by two diarthrodial facets with the extremity of the median bone of the canon ; their inferior extremity, slightly dilated and button-shaped, almost free and tangible to the finger, is united by a fibrous ligament to the region which we will study as the ergot. Thus constituted, the canon is articulated above, through the intervention of its component parts, with the lower row of carpal or tarsal bones, from which it receives and transmits impressions ; below, the middle bone forms with the first phalanx a very movable joint, which is completed, behind, by the two sesa- moid bones. No muscles worthy of attention exist in this region. The tendons of the extensor muscles of the phalanges are found on its anterior surface, and those of the flexors, perforans, and perforatus on the posterior. We must mention, be- sides, the carpal and the tarsal check tendons, fibrous, unelastic laminse, which emanate from the posterior ligament of the carpus and the tarsus; and ter- minate, after a more or less extensive course, in the deep flexor tendon of the digit. Two large synovial membranes exist, one above, the other below, upon about a third of the length of the canon. The superior we have already studied : it belongs to the carpal or the tarsal sheath. The inferior will be studied with the POSTERIOR MEMBER. 281 fetlock : it is that of the metacarpo- or metatarso-phalangeal sheath, also called the great sesamoid sheath. They both facilitate the gliding of the flexor tendons of the phalanges, the first against the posterior face of the hock or the knee, and the second over the angle of the fetlock ; both permit, besides, the movements of the two cords upon each other. Finally, against the posterior face of the principal bone of the canon, in a sort of gutter formed by the splint bones, is lodged the vast ligamentous brace of the fetlock, a (Fig. 93), which is bifid interiorly and terminates upon the sesamoid bones. It is not without interest to note, in passing, a somewhat infrequent fact of which science, nevertheless, has a certain number of examples ; we refer to the existence of supernumerary digits l on the internal face of the canon of one, two, or all four of the members of the horse at one time. This anomaly consists in the abnormal and almost complete development of the internal digit, which, in ordi- nary conditions, is simply represented by the corresponding but aborted meta- tarsal or metacarpal bone. The external digit occurs much more rarely. Professor R. S. Huidekoper has observed a very remarkable case in a Texas horse. The animal had, in all, ten hoofs, three on each anterior member and two on each posterior. The an- terior supernumerary digits were formed each of three phalanges ; their hoofs descended almost to the ground. The supernumerary digits on the posterior members existed only on the internal side ; their phalanges were rudimentary and their horny covering only reached to the middle of the pastern. 2 Role and Action of the Canon. The canon is a locomotory lever which plays a most important role in progression, station, and impulsion. Let us examine it rapidly from these diverse relations. It is primarily the seat of two principal movements, flexion and extemion. The first, much more pronounced in the anterior member, elevates the foot and places the canon in a favorable position to accomplish the second, which it is desirable should be as extensive as possible. The length of the forearm and that of the tibia are, as we know, in relation with the amplitude of these displacements. The movement of the canon in the two members is of an inverse order, on account of the opposite positions of the articular angles. When that in the anterior member is extended, it simply passes over the ground, places itself in prolongation with the radius, arrives thus on the soil, and preserves this attitude as long as the foot remains on the ground. In the posterior member, its extension commences a little before the foot is in station, and continues during the whole period that 1 Supernumerary digits constitute simply an example of the law of reversion to the penta- dactylous or five-toed type of the foot of the ancestral forms of the horse, as the eo-hippus, in which four digits exist. (Harger.) 2 R. Huidekoper, Note communique^. 282 THE EXTERIOR OF THE HORSE. the foot is on the soil in such a manner that, at its termination, when the foot is elevated, the tibia and the metatarsus are in a straight line. It is apparent from this that the anterior canon, in this action, is espe- cially utilized as an organ of support, whilst the posterior becomes a veritable agent of impulsion. This region, however, only fulfils a passive role in locomotion. It is an inert lever having no influence in itself upon the movements which follow or precede it, since it is traversed in its length only by tendinous cords, organs of transmission, and not by contractile muscles. It is the same during station : its vertical direction and its inertia make it a veritable column of support for the weight of the body, whose total pressure accumulates upon it. It is therefore very appro- priately disposed to fulfil this end. Besides being vertical, it also has an almost cylindrical form ; its median bone has parietes of great thickness ; the tissue which constitutes it is extremely compact ; finally, by the concurrence of the rudimentary bones attached to its lateral faces, it augments the area of the superior articular surface and serves as an important apparatus of breaking concussion in virtue of the double articulation which is found there and the obscure movements which are produced there. Its tendinous cords, even, and the posterior ligament, from their peculiar relations, present a special disposition to serve with .efficacy as an apparatus of support. The carpal or tarsal check tendon relieves the former by displacing a large share of the weight upon the bones, while the obscurely muscular nature and the mode of intercrossing of the fibres of the suspensory ligament of the fetlock 1 make this lig- ament a veritable elastic brace, which disperses the effects of the weight in such a measure as to render them compatible with the resistance and integrity of the tissues. Finally, the action of the canon in relation to the impulsion is not the same in the two members. This function, as we have seen, is more particularly imparted by the posterior members. The extensor mus- cles of the metatarsus are also provided with more powerful lever- arms. The calcaneus, by its length and by the prominence which it forms above and behind the centre of the tibio-tarsal articulation, places these muscles in very favorable conditions relative to the inten- sity of force and the rapidity of speed. 1 From the point of view of comparative anatomy, the suspensory ligament of the fetlock is, in fact, only a modified muscle which has its full development in the species whose hand and foot approach, by the number of their digits, the conformation which is observed in man. Thus, it occurs in quadrumana, carnivora, rodents, and many of the insectivora. POSTERIOR MEMBER. 283 Form. The canon is subdivided into four faces : an anterior, a posterior, and two lateral. They offer some slight differences according as they are examined in the anterior or in the posterior biped. Viewed from in front, the region is rectilinear in its length, rounded trans- versely, and widest towards its extremities. The lateral faces are flat, and leave the parts under the skin, which we already recognize, tangible to the eye and finger, namely, in front, the borders of the principal metacarpal or metatarsal bone; behind and above, under _the hock or the knee, the eminence -of the corresponding rudimentary bone ; below and a little above the fetlock, the button of this bone ; posteriorly and in the middle part, a groove augmenting in depth and width down to the fetlock, which separates the suspensory ligament from the principal canon bone ; it is in this groove that hernise or dilatations of the synovial membrane of the metacarpo- or metatarso-phalangeal articulations appear ; more posteriorly, the suspensory ligament of the fetlock, whose prominence increases from above to below ; then a second groove, less deep than the preceding, separating this ligament from the flexor tendons, and lodging the synovial dilatations of the great sesamoid sheath ; finally, the cord of the flexors, known in the exterior under the name of tendon, strong and resisting, which falls perpendicularly from the supra-carpal bone or the calcaneus upon the fetlock. The tendon, an eminence rectilinear from above to below, narrow and round from side to side, forms exclusively the posterior face. The skin of the canon, as well as the layer of the subcutaneous connective tissue, is more or less thick, according to the fineness of the race. These minute but important details which we have described are not observed in all subjects. They are the characteristics of horses of fine breeding and of good qualities. The hairs on the posterior face are always longer, more abundant, and coarser than the others, except in animals of the finer races, the Aryan or the English thoroughbred, for example. Coarse, sluggish, and lymphatic horses are remarkable, on the con- trary, for the abundance and the length of these hairs, which are only the origin of those of the footlocJc. Horsemen and many horse-owners have the habit of cutting, clipping, or singeing them, in the preparation of the animal for sale, in order to give to the members an appearance of fineness and of good qualities ; they are spared in draught-horses to make the limbs appear more voluminous. We will again have occasion to return to this practice in discussing the toilet. Beauties and Defects. The canon, in order to be beautiful, must be vertical, short, wide, thick, fine, and neat of outline ; its pos- terior part, or the tendon, must also be fine, unblemished, firm, and well detached. It is defective in opposite conditions. Direction. We have only one word to say on the subject of the direction of the canon, which should be perpendicular to the ground 284 THE EXTERIOR OF THE HORSE in order to duly sustain the body-weight, particularly in the anterior members, in view of their function and their closer situation to the centre of gravity. The least displacement forward, backward, out- ward, or inward makes the horse appear deficient in the axes; its articulations in certain regions are surcharged ; their constituent parts and the ligaments which unite them show signs, in the long run, of the concussions, of the violent tractions, a necessary consequence of the mode of superposition of the locomotory segments. Finally, the muscles themselves, supposing that the articulations are sound, are obliged to display more force in order to maintain the bones in a good direction, which in normal conditions claim but little of their co-opera- tion to preserve their equilibrium. The deviations of the canon are less prejudicial to the integrity of the locomotory apparatus when they are confined only to the posterior members; the animal is not less defective for this reason; only the effects of these alterations are slower in manifesting themselves. We will return to all these facts when we discuss the direction of the axes. Length. The absolute length of the canon merits to be taken into consideration in the case of rapid motors. It has not much im- portance in the draught-horse. In well-formed subjects, whatever may be the race to which they belong, the metatarsus is always longer than the metacarpus. We will say that, all things being equal, the latter are constantly longer in animals of speed, when compared in this relation to those of the draught-horse. With equality of form, the canon of the draught- horse is shorter than that of the thoroughbred; the body of the former is nearer to the ground and more voluminous than that of the latter, which, to use the comparison, appears, to a certain degree, mounted on stilts. It is easy to verify this statement by measure- ments which we ourselves have been careful to make before abandoning the classical opinion which claims that race-horses have their hocks as low as possible. We see, then, all proportions being of course consid- ered, that their canons are always longer than is believed. Hence these animals possess more speed, for necessarily they embrace at each step a longer expanse of space. The relative length of the canon should be studied with regard to the region which surmounts it, the leg or the forearm. We know already that the length of the broken radio-metacarpal or tibio-metatarsal lever in rapid motors is due to the development of the superior bone, the radius or the tibia. It is necessary, therefore, that the canon be in such cases short. When it is thus, we know that POSTERIOR MEMBER. 285 FIG. 94. the muscles experience less fatigue and contract to better advantage. A short canon is less heavy, oscillates more freely, unfolds itself more, and does not necessitate the same elevation of the member above the ground to reach the limit of its movements. Hence it is advisable to seek, in the pendulum under examination, a great ex- tent for the display of what we have already designated its active function ; in its passive func- tion the canon is inert, being incapable of accel- erating or slackening the movement which is communicated to it. (See Forearm and Leg.) Width and Thickness. The width of the canon is measured from before to behind, considering the animal in profile. It proceeds from the separation of the principal bone of this region from the flexor tendons of the phalanges, which procured also to the latter the designation well detached (Fig. 94). It is due, in the ante- rior members, to the volume of the antibrachial muscles ; in the posterior, to the width of the hock, which carries the summit of the calcaneus more behind. In each of the members it results, besides, from a more or less marked prominence of the sesamoid bones behind the fetlock articulation. Is it necessary to say now that this width is an absolute quality for all kinds of services ? Evidently not, since it is itself derived from other good points which we have already de- scribed, such as the volume of the muscles, the width of the articulations, and the length of the lever-arm. If, however, in theory, the width of the canon in the anterior member coincides generally with that of the fetlock, it is possible, notwithstanding the development of the latter, that the former may be deficient from ex- cessive narrowness at its superior part. The flexor tendons, being then too strongly tensed in the fold of the knee by the tarsal sheath, descend obliquely upon the sesamoids by gradually separating from the metatarsus, a vice of conformation which renders the tendons weak, less effective FIG. 95. 286 THE EXTERIOR OF THE HORSE. (Fig. 95). The horse affected with this fault appears slender in its build, which, in fact, lacks strength. Horse-dealers, in order to con- ceal it, leave the hairs at the upper part of the canon in arranging the toilet, while below they cut them off very closely, a deceitful procedure which it is easy to detect. The tendon in the posterior members is never weak, thanks to the particular disposition of the tarsal sheath. The thickness of the canon is measured, on the contrary, from side to side, viewing the parts either in front or behind. This dimen- sion, which indicates the transverse development of the principal bone, and, consequently, that of the regions between which it is placed, is always greater in the fore-limbs, columns of support, than in the hind, agents of impulsion. This is a fortunate adaptation of a part of the locomotory apparatus destined to fulfil such different functions. A thick canon, therefore, constitutes an absolute beauty, which denotes great strength of the members ; and because this is not the same in the well-bred as in the common horse of equal forms, because the meagreness of the canon in the former is not indicative of any weak- ness, it does not follow, as several authors have advanced, that such a conformation is not to be taken into account. H. Bouley has very forcibly elucidated how unwise this theory is, by saying, " The bones of the canon should be developed proportionately to the mass which they support" This conception is important. The slenderness of this region not only implies its feebleness of support, but it also involves that of the adjoining bones and of the tendinous apparatus which is annexed to it. A slender canon means a narrow knee ; the phalanges, the sesamoids, and the tendons lack proper development. In these con- ditions, the members wear away in a very short time, and so much more quickly as the body is heavier, as the animal is endowed, from his race, with greater energy. It is common to meet this defect in horses of poor conformation which are the product of injudicious selections or crosses. (H. Bouley.) When the region lacks width and thickness, the canon is called meagre, narrow, slender ; when to these characters is added an excessive length, the animal is said to be mounted upon matches; finally, this same horse has nothing under his knee when the tendons are not suffi- ciently developed, while the member is qualified well cast when the tendons of the flexors are strong and well separated from the bones which constitute its lever-arm. Fineness. The fineness of the canon is characterized by the thinness of the skin and the spareness of subjacent connective tissue, POSTERIOR MEMBER. 287 which expose to external view, in all their details, the bones, the sus- pensory ligament* the tendons, and the blood-vessels. This state indi- cates a noble ancestry ; it is found in horses of the distinguished races and those of their race which show their lineage. This quality can habitually be perceived by a glance of the eye ; but many also endeavor to appreciate it by passing the hand over the lateral faces of the region, a manner of procedure which has primarily the advantage of betraying the existence of blemishes. It is necessary to attract the animal's attention before practising this manipulation upon the posterior members, in order to avoid his kicking or biting. In common subjects, even in the best, the skin is thick and the connective tissue abundant. When carried to the extreme, these char- acteristics cause the canon to be spoken of as round and the tendons as fleshy, defects essentially prejudicial in pleasure-horses, in which the distinctness of the lines and the fineness of their extremities are the indispensable conditions of their value, while in draught-horses no importance is attached to them. Density. The firmness of the tendons denotes the density of the tissues, the energy, the quickness of movement, the blood, the race, and the resistance of the constitution. This is ascertained by the sense of touch and not by striking the cord of the flexors with . the foot, which some persons practise to judge of it as well as of the solidity of the member. It is easy to comprehend that such a method can give no positive information, since it is the surprise and not the weakness of the parts which causes the horse to flex the limbs. Neatness of Outline. This neatness that is to say, the absence of blemishes is the most important qualification to be realized in the examination of the canon. It is indispensable that to the inspection and to the touch the outline should be normal ; that the ridges and grooves of this region, which we have described, should be quite marked without any alteration. Diseases and Blemishes. First among these are skin wounds resulting from contusions and kicks given or received by the animal. When these are the result of the repeated contact and friction of thie opposite feet during locomotion they receive the name speedy-cut, and the animal is said to overreach himself, strike himself, cut himself. We will again return to them when treating of the defects of the gaits. It is not rare, either, to see blood-tumors, hot abscesses, and inflammatory enlargements of the subcutaneous tissue or of the lymphatic vessels on the internal face of the canon. Lymphangitis of a malignant type, often symptomatic of a glandero-farcinous diathesis, has a favorite seat in this region. Let us also indi- cate the enormous indurations of the skin and the subjacent connective tissue, 288 THE EXTERIOR OF THE HORSE. very common upon the posterior members and completely deforming the regions between the hock and the hoof. These indurations, known under the name of fibrous elephantiasis (Trasbot) on account of their analogy with elephantiasis in man and of the aspect which they give to the members, are sometimes compli- cated by lesions of the bones. In spite of their hardness, their volume, and the pressure exercised on the organs which they cover, they do not occasion very great inconvenience in walking and permit the utilization of the animal at a slow pace. They are rebellious to all treatment, and the very means employed to combat them have no other result, in most instances, than the development of an activity analogous to that which is observed in similar cases in the forma- tion of neoplasms, which may have with them, according to our colleague, Professor Trasbot, a closely-related origin. We will also cite the hard and indolent enlargement of the tibial aponeurosis at the point where it terminates on the tendons of the extensor muscles of the phalanges. This induration, which is located at about the superior third of the anterior face of the hind canon, is susceptible of ulceration under the influence of friction, and seems more particularly confined to English thoroughbred and other horses of great speed. Eczema (grease, water in the legs}, a chronic affection of the skin, somewhat scarce to-day, consisting of an abundant and fetid exudation on the very lowest part of the member, may ascend to the posterior region of the canon when it is of long standing. Although not disabling the animal from work, this should nevertheless be considered serious, from the uncleanliness which it engenders and the care which it necessitates. Contusions and ruptures of the tendons of the canon are frequent in the anterior members, while in the posterior they are, so to speak, at least from our own experience, almost unknown. Designated under the name over-stretching, or, better, strains of the tendon, they result from traction or partial lacerations of the tendinous fibres during the violent efforts of locomotion at great speed. This alteration of the tendons or of the structures situated more deeply (check tendon) is followed by a more or less acute inflammation accompanied at the beginning by a severe lameness and succeeded soon by an enlargement, which renders the organs knotted and always very sensitive. The symptoms, at the end of a certain period, ameliorate, but the swelling and the lameness persist, while the contraction of the tendons and the consecutive deformity of the angle of the fetlock take place. For these reasons, over- stretching is a grave accident. It depreciates so much more the value of the animal as he is intended for pleasure and parade, and as it is neces- sary to employ the most energetic means of treatment against it, such as tenot- omy or the actual cautery, whose indelible traces have all the characteristics of the most permanent blemishes. It is vulgarly said of the hippodrome horse which meets with the accident on the race-course, that he has snapped a tendon or that he is broken down. The most common blemish of the canon, involving the bones themselves, manifests itself by the presence of osseous tumors, known under the name of splints. These exostoses, in the majority of cases, have their seat on the interosseous ligament which unites the rudimentary metacarpal or metatarsal to the principal bone of the canon. Those which exist on the anterior face of the latter are the POSTERIOR MEMBER. 289 result of contusions and have little gravity ; they are in most instances absorbed spontaneously, are much more rare, and only appear accidentally at all periods of life. Splints occur more often upon the anterior members than upon the posterior, and on the internal side than the external. This is due to their cause of develop- ment. They proceed, in fact, from tractions exerted on the interosseous ligament under the influence of the vertical pressure which is exercised on the head of the splint bones during rapid locomotion. As long as these small bones axe-not soldered to the principal bone in consequence of the normal ossification of their ' ligament of union, they tend to glide up and down in a measure proportional to the weight which they sustain. Whence results rupture of the ligamentous fibres, which is propagated to the periosteum, irritates the latter, and causes a periostitis with the appearance of one or more tumors upon the tract of the rnetacarpal or metatarsal synarthrodial articulations. It is easily understood from this that tne formation of splints is a disease more frequent in young horses used too young, and without moderation, for heavy work, than in old horses, in which the process of co-ossification of the bones of the canon has already been completed. It can also, without difficulty, be perceived that they should be more common on the anterior limbs, nearer to- the centre of gravity, which receive, more especially, the effect of the quantity of movement at great speed. Finally, it is equally easy to explain their habitual presence upon the internal side if we only recall : first, that the weight of the body presses more upon the internal side of the articulation ; second, that the pressure sustained by the bones is proportional to the area of compressed sur- faces. Now, in this connection, it is to be remarked that, all proportions being considered, the articular surfaces of the internal metacarpal or metatarsal bones are larger than their homologues of the external side; whence it follows that these bones are more disposed to glide against the median piece which supports them than the external, and, consequently, to lacerate their interosseous ligament. Splints, the volume of which varies from that of a small hazel-nut to that of a hen's egg, are characterized externally by the relief which they form under- neath the skin, and by a sensation of hardness which is conveyed to the hand on palpation. They are readily perceived if the canon be viewed from in front. 1 Their disposition is very variable : sometimes only one exists (simple splint) ; sometimes there are two, situated almost on the same level on each side of the region (pegged splints) ; at other times there are several in succession from above downward, upon the same face, and of an almost uniform volume (chain splints) ; finally, there are some which, in relation to size, form a decreasing series from above downward, on the one side or the other (spindle-shaped splints). Whatever may be their form, these tumors are more grave as they are situ- ated towards the carpal or the tarsal articulations, or are developed in the posterior gutter destined to lodge the suspensory ligament of the fetlock. In this case they cause an evident constraint and induce too often a persistent lameness. Most ordinarily a splint lames a horse, only at the first, when the inflammatory process of the periosteum is still in full activity. The lameness disappears as soon as the tumor is quite developed. * 1 The buttons of the rudimentary metatarsal or metacarpal bones should not be mistaken for splints. 19 290 THE EXTERIOR OF THE HORSE. Fractures of the canon, though rather common, are, so far as our study is concerned, absolutely deprived of interest. We should, nevertheless, mention some: they are those of the rudimentary metacarpal or metatarsal bones. Kesulting from traumatisms, they give rise to a complication, similar to the for- mation of a splint, at the point of union of the two osseous segments. As to the synovial dilatations of the canon, they properly belong to either of the regions between which the canon is situated. The superior have already been pointed out with the knee ; they are due to an abnormal distention of the carpal sheath. The inferior, known under the name of windfalls, consist of a hydropsy of the synovial membrane of the metacarpo-phalangeal articulation, or of the great sesamoid sheath, and will be studied with the fetlock. Finally, there are also found, along the length of the canon, traces of actual cautery of varying area and configuration, which indicate, according to their situ- ation, that the animal has been treated for disease of the osseous apparatus, the tendons, or the synovial membranes. In spite of these markings, the alterations of which they are the evidence may not have disappeared, and it is wise, conse- quently, to submit the member which presents them to a minute examination. In any case, the horse has none the less lost at least a part of his value, for he is blemished, and so much more gravely as the treatment to which he has been subjected has been less efficacious. G. The Fetlock. Situation ; Limits ; Anatomical Base. The fetlock is situ- ated between the canon and the pastern. It supports, at its posterior part, a horny production, the ergot, and a tuft of hair to which has been given the name of footlock. It has for its anatomical base the metacarpo- or the metatarso-phalangeal articulation, which results from the apposition of the inferior extremity of the principal bone of the canon and the superior extremity of the first phalanx, complemented behind by the great sesamoid bones (Fig. 96). These bones are united by numerous ligaments : an anterior or capsular ; two lateral funicular, a; a posterior, the suspensory of the fetlock, which has already been mentioned, and whose two branches terminate upon the sesamoid bones, a (Fig. 97); finally, the group of inferior, b (Fig. 97), and lateral, b (Fig. 96), sesamoid ligaments, short and strong, which fix these bones to the first phalanx and the canon. The two sesamoid bones are, moreover, intimately united to each other by means of a fibre-cartilaginous mass which transforms their poste- rior face into a pulley, c (Fig. 97), upon which the flexor tendons of the phalanges glide. This ligamentous apparatus, of great strength, is, in addition, reinforced by the extensor tendons of the phalanges in front, and by the flexor tendons behind, which also fulfil the role of suspensors like the superior sesamoid ligament, fdiose function they supplement. Three distinct synovial membranes exist in the region of the fetlock : one articular and two tendinous. The first, firmly maintained in front and on the sides, can become dilated POSTERIOR MEMBER. 291 behind and above, between the canon bone and the suspensory ligament of the fetlock ; behind and below, upon the sides of the first phalanx. The largest of the tendinous synovials, posterior to the articulation, subserves the gliding of the tendons against the sesamoid pulley ; it is known by the name FiG. 96. FIG. 97. of great sesamoid sheath. Extending from the inferior third of the canon to the superior part of the second phalanx, and unequally sustained by the surrounding tissue, it sometimes forms a dilatation on each side, above the fetlock, between the suspensory ligament and the flexor tendons. It presents, also, along the length of the pastern, two weak points, of which we will only make mention, and whose enlargement is always much less marked than that of the preceding. The second and the smallest of the tendinous synovials is found in front, underneath the tendons of the extensors of the phalanges, and permits their gliding upon the anterior face of the capsular ligament. It is extremely rare that it communicates with the articular synovial membrane. It is susceptible of becoming distended over its whole periphery, unsustained by the tendons, and even of rupturing its parietes into the surrounding connective tissue under the influence of internal pressure. Mechanism of the Articulation of the Fetlock. By rea- son of the oblique direction of the first phalanx and of its superior articular surface, which play, with regard to the weight of the body, the role of an inclined plane, the principal bone of the canon constantly 292 THE EXTERIOR OF THE HORSE. FIG. 98. tends (Fig. 98) to press on the sesamoid bones, A, and tends to effect a closing of the angle PEC. The ligamentous apparatus, however, and the tendons which exist behind this angle, constantly re- sist this tendency and, by their tenacity as well as their elas- ticity, transform the articular joint into a veritable elastic spring admirably adapted to the sustentation of the body, the dispersion of the reactions, and the impulsion of the mass. The suspensory ligament of the fetlock, being resisting and elastic, thanks to the few mus- cular fasciculi which enter into Its composition, yields more or less, according to the intensity of traction which it undergoes, to the lowering of the great sesa- moids, and through its attach- ments upon the bones of the canon distributes upon the latter a portion of the pressure of the weight of the body, in such a measure as is compatible with their integrity. As to the cord T, of the flexor tendons, though much less elastic, it acts in the same manner upon the extremity of the lever-arm AB, in order to limit to some extent the movement of descent of the fet- lock and prevent the elasticity of its suspensory ligament from being strained beyond its limits. But as it is continuous, superiorly, with the fleshy portion of the corresponding muscles, and as an intermission in the action of all these contractile organs is necessary, there exists, behind and below the carpal and the tarsal articulations, a strong lig- amentous band emanating from the posterior capsular ligaments of the latter, which permits the flexor tendons to perform the role of passive organs of suspension, by giving them a function completely independent of their respective muscular portions. The carpal and the tarsal check ligaments therefore transfer to the superior part of the canon bone the remaining pressure of the body-weight which has not been completely overcome by the elasticity of the suspensory ligament of the fetlock. Hence their force of resistance is in relation with the intensity of the tractions which they must support, and it is for this reason that the POSTERIOR MEMBER. 293 carpal check tendon always has a greater volume than its homologue in the posterior member. The function of the fetlock is deduced from the preceding consid- erations. It is a veritable elastic mechanism or spring, which consti- tutes, for the weight of the body, an apparatus of sustentation and an apparatus of dispersion ; it relieves the muscles charged with the sup- port of the body, at the same time that it prevents, by its elasticity, the effects of the concussion of the latter against the ground. External Form. Viewed in front, the fetlock forms a spheroidal relief circumscribed laterally by two convex lines which are continuous above and below with the lateral faces of the canon and of the fetlock. Viewed in profile, it is limited, on the contrary, in front by a concave curve which continues symmetrically the profile of the anterior face of the adjoining regions, while, behind, it presents a salient angle whose superior branch is tangent to the tendons, and whose summit corresponds to a tuft of hairs, the footlock, containing in its centre the horny production called the ergot. A fine skin with short hairs covers it and, to a certain point, enables one to conjecture its anatomy in highly-bred horses. In horses of the common races, on the contrary, the external details are more or less masked in consequence of the thickness of the integument and the quantity and coarseness of the pilous production. The region is also, in such cases, the object of special care on the part of dealers, which consists in removing the hairs of the footlock in order to give to the animals an appearance of fineness and distinction which they do not in reality possess. We will again return to this in the chapter on the toilet. Beauties. The fetlock, like all the articulations, in order to be beautiful, should be wide, thick, well directed, fine, and free from blemishes. Width. The width is given by the extent of the antero-posterior diameter, and is appreciated, consequently, by examining the horse in profile. It depends upon two elements : the volume of the inferior extremity of the canon and that of the sesamoid bones (Fig. 98) ; whence it is apparent that it should be ample, for it is proportional to the firm- ness of contact of the members, to the extent of the movements, and, finally, to the length of the arm of the lever AB, whose development favors the action of the suspensory apparatus of the tendons and of the suspensory ligament of the fetlock. When the articulation is narrow, the tendon is close to the canon, the animal has little firmness of step, lacks force, and is ruined all the quicker as the members are weaker as columns of support in relation to the body. 294 THE EXTERIOR OF THE HORSE. Thickness. The thickness is the transverse diameter. It indi- cates the large development, from side to side, of the inferior extremity of the canon and of the corresponding part of the first phalanx. It is needless to insist upon the advantages of these peculiarities ; it stands to reason that they denote large articular surfaces, and firmness and sureness of the step, important conditions to exact whatever may be the service. The fetlock which is deficient by lack of width and thickness, by lack of volume, in a word, is called small, round ; the animal is also said to have thin, light wrists, to be wanting in the wrists, to have weak pins, etc. Direction. To the two preceding qualities it is important to add a third, that is, the good direction of the segments which concur to the formation of this articulation. We know already that one of them, the canon, should be vertical ; as to the other, it implies a certain obliquity which we will determine when we treat of the pastern. Suffice it to say for the present, that this obliquity would be greatly exaggerated if it attained only 40 or 45 degrees with the horizon ; in any well-conformed horse it attains at least 55 degrees. When the branches of the spring represented by the fetlock straighten themselves one upon the other, their angle becomes more and more obtuse and even tends to become effaced. The animal is then said to be straight in the members, in the fetlocks. In certain cases, however, the deviation of the segments is such that their obliquity takes place in a sense inverse to that which they normally affect ; the summit of the articular angle is directed forward while its sine looks backward. This is a somewhat common deformity to which the name knuckling has been given. We will treat of this with the pastern and the axes of the members. At other times, an accidental, momentary deviation results from fatigue, and exists only in the fetlock of the posterior members, which are suddenly projected forward when the animal stands still and reassurae their proper situation as soon as he steps out again. This singular attitude, which is manifested also in the stable, is expressed by saying that the horse is at roost. Finally, when this deviation, instead of being parallel to the median plane, in front of or behind the axis of the member, is situated in an oblique plane, outward or inward, in relation to the median plane of the body, the horse is qualified splay-footed or parrot-toed. It is a vice of the axes of the members which we will study in a future chapter. Fineness. The fineness or dryness of the fetlock implies a POSTERIOR MEMBER. 295 delicacy of the skin and of the hairs which cover it, spareness of the subcutaneous connective tissue, and the precise and clean delimitation of all its parts. It is considered as an index of quality, temperament, energy, and vigor. When it is not thus the region is called puffy. In this respect, horses of the finer races approach those of the common races according to the condition they are kept in. We have known a rather large number which, working in low and moist countries, or-npon muddy and filthy soil, had in the long run acquired long and abundant hairs and more or less thickened extremities. Absence of Blemishes. The fetlock is dean when it is exempt from blemishes and from diseases. The rationale of this beauty will be apparent from what follows. Diseases and Blemishes. From the situation which the fetlock occupies, numerous diseases, acute and chronic, as well as accidents, may affect it, which depreciate the animal in different ways. The skin, first, is often the seat of excoriations, contusions, and wounds, most frequent on the inner side, and resulting generally from injuries which the sub- ject inflicts on himself during locomotion. It is then said that the horse over- reaches, interferes, cuts himself, strikes himself; he is usually affected with a defec- tive axis of the parts, and ordinarily has an ungraceful gait. (See Defects of the Gaits.) Like the knee, the fetlock becomes more or less gravely lacerated on its anterior face in consequence of falls upon hard and irregular soil. At other times it presents cicatrices, callosities, or traces of the actual cautery in points or in lines of a variable extent and configuration. The integument sometimes, but more rarely, offers an abundant, fetid exuda- tion, which transudes from warty excrescences called fid, and agglutinates the scattered hairs over the diseased surface. This disease, known under the names of water in the legs, grapes, fid, and grease, etc., is an index of a soft constitution and a lymphatic temperament, dependent most often upon bad hygiene. It is regarded as grave on account of its chronic state, its tendency to ascend into the region of the canon or descend towards that of the foot, of the putrid odor which it gives off, and of the tenacity which it offers against all means of treatment. The connective tissue is frequently the seat of oedema, cysts, hcematoma, (blood-tumors), abscesses, lymphangitis, fistulous wounds, etc., occasioned by very diverse causes, to concern ourselves with which would be beyond our province, the acute character of all these affections being given. It is not the same, however, with cystic tumors, which are met either on the internal or on the anterior face, and which proceed nearly always from repeated contusions during locomotion. The cyst on the anterior face, sometimes very voluminous, produces an abnormal convexity of the region, when it is viewed in profile. This swelling is indolent, uniformly fluctuating and somewhat tense, whatever may be the attitude of the member, which permits it to be diagnosed from a synovial dilatation. It is not serious, but constitutes a decided blemish in pleasure-horses, in consequence of the deformity which it entails. 296 THE EXTERIOR OF THE HORSE. The cyst on the internal face, always much smaller, lies upon the tract of the internal lateral ligament of the metacarpo- or metatarso-phalangeal articula- tion. Its symptoms are the same as those of the preceding, but the blemish which it occasions is less grave. A propos of the canon, we have spoken of the enormous indurations of the subcutaneous connective tissue which Professor Trasbot designates under the name of fibrous elephantiasis of the members. In the region of the fetlock they acquire at times colossal dimensions. H. Bouley * has seen some that extended from the inferior half of the canon to the hoof, which they enveloped like a hood. Measuring more than a metre in circumference, they touched the ground behind, with the foot in station, and rubbed, in walking, against the opposite member, into which they had made a deep cut. Two tumors of this nature, of which Prudhomme' 2 has given the description, weighed twenty-one kilos, and twenty-seven kilos, respectively. The deep base of these enlargements is ordi- narily formed by extremely-developed vegetations from the periosteum. The most common lesions of the fetlock, those which indicate at a glance the excessive function of this articulation and the premature wearing away of the member, are without doubt the tendinous or articular synovial dilatations, which have received the generic name windgalls. One of these dilatations, however, that of the synovial bursa, facilitates the gliding of the extensor tendons over the superficial surface of the anterior cap- sular ligament of the articulation, and could with equal propriety be called anterior windgall. In relation to its development, it is absolutely identical with the others. It must not be confounded with the anterior cyst, of which we have spoken above. Like the latter, it determines an abnormal swelling upon this region according to the degree of the synovial hydropsy ; but what will always permit it to be differentiated from the preceding is its relative situation with the tendon. In the first case, the tendon is never located upon the surface of the tumor ; in the second, on the contrary, it is most usually the reverse, unless, under the effect of extreme distention, the somewhat weak parietes of the synovial membrane allow some of the contents to escape into the interspaces of the surrounding connective tissue. Before things have gone so far, however, over the middle of the anterior face of the tumor is seen a vertical gutter which renders it bilobed, and which is due to the compression exercised by the anterior extensor tendon of the phalanges. Rarely does the anterior windgall of the fetlock communicate with the articular synovial. Still, such a communication may be present (Kigot), and it is easy of appreciation, for other lateral dilatations will be found coexist- ing with it, pressure on which is integrally transmitted to the former (Bouley). The true windgalls are of two varieties : articular and tendinous. It is impor- tant to be able to distinguish them. Articular windgalls appear above the fetlock in the form of two small, round tumors, one on each side, tense when the member is in station, and softer when it is elevated. They are situated exactly in the angular space comprised between the border of the principal canon bone and the corresponding branch of the suspensory ligament of the fetlock. It is only when they have attained a large 1 H. Bouley, loo. cit, p. 580. 2 Prudhomme, Hecueil de mexlecine vSterinaire, 1844, p. 589. POSTERIOR MEMBER. 297 volume that there appears, against the first phalanx, in the fold of the pastern and on each side, the outline of two other tumors, always much smaller, whose fluctuations are transmitted to the preceding. We have seen that these are the points of the synovial membrane which are only feebly supported. Tendinous windgalls, formed within the great sesamoid sheath, are more voluminous and ascend higher than the articular, behind which they are located. Their exact position is the space comprised on each side between the suspensory ligament and the tendons ; it is the point which corresponds to the superior, culs- de-sac of the sheath in question. Below the fetlock there are two other smaller tumors, in the fold of the pastern and along the latter border of the flexor tendons ; they communicate with the superior, but are only visible in a state of extreme dilatation of the sheath. The parietes of windgalls in time become thickened, indurated, and ossified. The accumulation of a large quantity of synovia in their interior renders the movements less easy, and occasions painful pressure upon the surrounding tissues; and, in consequence, the articulation itself becomes deviated from its normal direction owing to the mechanical restraint which it experiences and the pain which it causes during station. The tendinous cords, relieving themselves instinctively, so to speak, from their habitual tension, retract and tend to produce, little by little, a more or less complete eifacement of the angle of the fetlock, a complication always grave by reason of the vicious axis of the members which it occasions, knuckling. It is then that the articular extremities, deprived of their apparatus of dispersion, manifest the violence of the concussions which they experience during locomo- tion by the appearance of osseous formations upon their periphery. The exos- toses, whose formation is excited under the influence of these causes on the anterior and the lateral faces of the fetlock, have received the name osselets. Generally speaking, the chronic diseases of the region, which we have enumerated, are compatible with the normal function of the joint. But the hard indurations of the tissues and the formation of osseous vegetations around the articular margins produce a certain restraint of the movements. In spite of the variable stiffness of the members, the animal is still utilizable. A decided lame- ness, save in exceptional cases, appears only after a long time, when, for example, the synovial membranes are very distended and the articular surfaces notably altered. H. The Footlock and the Ergot. The footlock is a tuft of hairs situated behind the fetlock, around the ergot. Properly speaking, it merits but little attention when a horse is examined for soundness. It is small and formed of hairs of fine texture in the finer races, while in the common races, whose pilous system at the inferior part of the member is, in general, thick, coarse, and very extensive, especially if the subjects inhabit low and damp localities, it presents the opposite characters. It is not rare to see, in these, the hairs of the footlock touch the soil and often ascend to the posterior part of the knee. Many horse-merchants, in doing up the hairs, do not fail to cut the 298 THE EXTERIOR OF THE HORSE. footlock to the form of that in the English thoroughbred, in order to give to their horses an appearance of fineness and quality which they do not really possess. The ergot is a more or less voluminous horny production, which occupies the posterior part of the fetlock in the middle of the hairs of the footlock. In relation to comparative anatomy, by reason of its situation, its connections, and the structures which form its base in some species, it is considered as the vestige of an aborted digit. It is, however, with- out interest from an external point of view. Like the footlock, it acquires quite a great length in common horses. It is sometimes seen to divide under the influence of desicca- tion, and in the end is shed off 1 . When it is too voluminous, it is cut when the hairs of the footlock are being arranged, a useless practice in well-bred animals, for with them it always has very feeble dimensions. The ergot, in spite of its apparent insignificance, plays none the less a certain rdle of protection, in locomotion at great speed, in relation to the posterior part of the fetlock, which the violence of the reactions tends to lower to the ground. It is common to see on the race-course, after a race, horses whose ergots are covered with blood from their use, an evident proof that the fetlock must go down to the ground at each time of the contact. It is always, in this case, the diagonal biped upon which the horse gallops that is most injured, a result easy of ex- planation, since the feet which constitute this biped support, in succes- sion and singly, all the weight of the body multiplied by the velocity of the locomotory movements. I. The Pastern. Situation ; Limits. The pastern is situated between the fet- lock and the coronet; it is the narrowest part of the member of the horse, and owes without doubt to this characteristic the name wrist, by which it is also designated in ordinary language. Anatomical Base. Its osseous base is formed by the first pha- lanx, which gives to it, consequently, its oblique direction from above downward and behind forward. We have made mention above (see Fetlock) of all the mechanical advantages which depend upon the inclination of the superior articular surfaces of this bone ; others will be noticed when we discuss the obliquity of its great axis. We will also revert to them in describing the function of the pastern as an inclined plane receiving the weight of the body and transmitting it to POSTERIOR MEMBER. 299 the hoof, besides disseminating it in part upon the environing reten- tive apparatus. The first phalanx is united behind to the sesamoid bones ; above, to the principal bone of the canon through the medium of ligaments which we have already enumerated. (See Fetlock.) Inferiorly, it is firmly articulated with the second phalanx by the lateral ligaments, e, c (Fig. 96), which are common also to the articulation of the foot. These means of union are completed, anteriorly, by the tendon of the ante- rior extensor of the phalanges ; posteriorly, by the cord of the flexors, separated from the inferior sesamoid ligaments, b, b, b (Fig. 97), by the inferior cul-de-sac of the great sesamoid sheath. Movements. The pastern is the seat of two movements, flexion and extension. Each of these modifies the opening of the metacarpo- or metatarso-phalangeal angle, which, in a state of repose, can be con- sidered as in an attitude of extreme extension. They have, however, not the same value. Almost insurmountable anatomical obstacles, as we have seen, hinder a greater extension ; these reside in the presence of the suspensory ligament and the flexor tendons upon the summit of this angle ; a fortunate disposition, in virtue of which the bones main- tain their function in sustaining the body, without being exposed to too violent effects from the tractions of the extensive displacements of the latter. The flexion of the pastern, on the contrary, has, so to speak, no definite limits. The articular movement is capable not only of causing a disappearance of the primitive angle, but even of giving it a disposition inverse to that which it occupied at first. In this case, the obstacle to the closing of the new angle is entirely mechanical ; it is due to the presence of the sesamoid bones and the soft tissues, which interpose their thickness between the canon and the phalangal segment. At the moment of the contact, when the body-weight is thrown on the member, the fetlock is pushed backward and downward, and the pastern tends to become horizontal. It then gradually becomes straightened upon the canon until towards the termination of this phase. The two segments are now almost in a straight line. The pastern then becomes strongly flexed, elevates the foot, and is finally placed in prolongation with the canon to commence again the phase of contact with the ground. These diverse attitudes have been accu- rately recorded by MM. Marey and Pages by means of instantaneous photographs. 1 Form. The anterior face of the pastern is slightly constricted in its middle, particularly in horses in which this region is somewhat 1 Marey et Pages, Analyse cinmatique des allures du cheval, in Comptes-Rendus des stances de 1' Academic des sciences, Paris, 27 Septembre, 1866. 300 THE EXTERIOR OF THE HORSE. long ; the posterior face, less extensive, and known under the name fold of the pastern, is the centre of the movement of flexion of the hoof upon the phalanges ; finally, the two lateral faces, almost subcu- taneous, are crossed from above downward, and from before backward, by a ligament of constraint which the suspensory of the fetlock sends to the tendon of the anterior extensor of the digit. The skin which covers this region is more or less thick according to the race ; the hairs also have a variable abundance and texture. Beauties. The pastern should be wide, thick, of medium length, well directed, fine, and free from blemishes. Width and Thickness. The width is measured in an antero- posterior sense, viewing the animal in profile ; the thickness, on the contrary, is appreciated from side to side, examining the subject in front. Great importance is attached to the development of both of these dimensions. The width gives the measure of the volume of the first phalanx and of the tendons which pass over its two faces. The thick- ness indicates the transverse development of the articular surfaces, which, we know, is correlative to that of the fetlock and that of the coronet. Now the principal condition to be realized in the solidity of the members of the horse is the volume of the bones and the ligaments which unite them, in order to maintain their locomotory angles ; we judge of it, therefore, in relation to the body, as a whole, keeping in view the thickness of the segment and the abundance of the hairy productions which cover them. Length. -To assign an absolute length to the pastern would oblige us to enter into too many minute details, as the excess or the deficiency of this element can be, and quite frequently is, compensated by a more or less oblique direction of the phalanges under the canon. The various differences in this respect can be quickly recognized by the practised eye. We will therefore refer to them only to show the advantages and the disadvantages dependent upon these variations, with regard to the particular service which a horse is destined to perform. A horse whose pasterns are too long is called long-jointed; he is short-jointed in an opposite sense. Each of these conformations is regarded as an absolute defect, if it be not compensated, in part at least, by a proper direction, as we shall see farther on. Until now, and for convenience of demonstration, the phalangal segment was considered as an almost rigid column extending from the fetlock to the ground. POSTERIOR MEMBER. 301 This view, too absolute in its character, has been recently opposed by our colleague, M. Pader, 1 who has pointed out with reason the articulation of the foot that is to say, the last inter-phalangal artic- ulation, and not the hoof as the centre of the movements of rotation of the phalangal lever upon the soil. This statement being made, the phalangal segment may be repre- sented schematically, during station, by the angular lever A OB (Fig. 99), which rests by its point, B (fixed point), upon the third phalanx, and receives at (fetlock) the weight of the body, OR, transmitted through the canon, OC. The muscular action, M, exercised upon the sesa- moid bones, A, must there- fore, at each instant of the contact, in order to main- tain the equilibrium, an- tagonize the force, J?, and counterbalance it, so that the fetlock, 0, where it is applied, may remain in its normal situation. Let us now draw, from the point of support, B, the per- pendiculars BF and BE upon the direction of the two forces, M and R; these lines, it is seen, are the respective lever- FIG. 99. arms of each of these forces, and it will be seen that here, as in all levers of the second class, the arm, Bf\ of the power overcomes that, BE, of the resistance. It is known, besides, that a lever is in equilibrium when the movements of the two forces are equal. Whence, since equilibrium does exist, we have the following formula : M X BF (mom. of the force M) = EX BE or ///(mom. of the force K). This being laid down, let us now lengthen the pastern, and make it OD, for example. The new arms of the lever will be DG and DL Both will be lengthened by the same quantity, HD, which will necessarily disturb the equilibrium, for the arm of resistance will have augmented, relatively, by a greater quantity than that 1 Pader, De la ferrure normale, in Bulletin de la Soc. cent, de raed., vet. annee, 1888, p. 497. 302 THE EXTERIOR OF THE HORSE. of the power. The absolute augmentation, however, being equal for both, the preservation of the equilibrium will demand that the power or the muscular contraction be more intense to counterbalance the resistance, or the weight of the body, whose arm has lengthened beyond the limits required by the mechanism of the parts. Whence it follows that the elongation of the pastern increases the force R at the expense of the force M, because its effect is to lengthen the arm of the lever by the same quantity, instead of in an inverse ratio to the forces which move them. During locomotion, when the foot has reached the ground, it is no longer the first two phalanges that constitute the phalangal segment, as M. Pader 1 believes, but it is the entire digital re- gion, the hoof included. These form, it is true, a broken lever composed of two pieces (1st, the first two phalanges ; 2d, the hoof), but their successive movements, always in the same direction, are so closely associated as to give to the total displacement a unity analogous to that produced by a rigid lever, OB (Fig. 100), extending from the soil, B, to the fetlock, 0. With a quantity of movement that varies ac- cording to the weight of the body and the velocity of the gait, the extremity, B, of this segment comes, at each step, in contact with the ground, xy, which necessarily reacts in proportion to the action which it communicates to the hoof. It is easy to convince ourselves that this action is also modified by the variations in the length of the digital region. Let the line BH represent the force which, acting at the extremity, B, of the lever, BOA, tends to rotate it around the point 0, and, consequently, to close the FIG. 100. Pader, loc. cit. POSTERIOR MEMBER. 303 angle BOO, by antagonizing the muscular action, M, which is exercised at the extremity, A, of the same lever. In this case, the fetlock becomes the fixed point or fulcrum and the lever belongs to the first class. Let us determine, as above, the arms of the lever of the forces, BH and AM, by inserting from the fixed point a line perpendicular to their direction; these arms evidently are OH and OA. Now let us lengthen the lever OB to OD, and we will see that the arm of the force, Bff, becomes 01, while that of A M will always remain OA. Thus, the longer the pastern the more the reaction of the soil against the weight of the body augments and fatigues the tendons and the ligaments which are inserted, at A, upon the sesamoid bones. The causes which tend to augment the length of the phalangal region are very significant, exception being made, of course, of the dimensions of the bones. First among these we will place the elongation of the hoof, re- sulting from the normal growth of the horn in a horse whose shoe is not sufficiently often reset ; secondly, the error of the farrier in not sufficiently paring the foot; finally, the tendency which farriers or proprietors have, according to their interests, of applying too thick a shoe in order not to have the trouble or the expense of re- setting them at proper intervals, as often as the state of the hoof re- quires it. Deficiency of the length of the pastern evidently has inverse draw- backs. The short-jointed horse surcharges his bones beyond measure ; he lacks suppleness in consequence of the insufficiency of the fetlock as an apparatus of dispersion, and has, from this fact, hard reactions ; besides, he is more predisposed to osseous blemishes of the bones of the members, as ring-bones. The inconveniences of the long joints and the short joints have not, by far, the same importance in the anterior as in the posterior mem- bers, on account of their unequal distance from the centre of gravity. It is beyond a doubt that the anterior extremities, incomparably more loaded than the posterior in the sustentation of the body, show more quickly and more gravely the injurious consequences of these defects. In fact, experience has demonstrated this ; blemishes of the anterior members are more common than those of the posterior, and the part which the pastern takes is more marked in the former, this region being always longer in the fore than the hind limbs, and also more oblique, doubtless on account of their proximity to the centre of gravity. Direction. The direction of the pastern is intimately allied to its length, that is to say, a long pastern is in most cases too horizontal, 304 THE EXTERIOR OF THE HORSE. FIG. 101. FIG. 102. while it becomes more vertical when it is too short. In the first case, the horse is low-jointed ; in the second, he is qualified straight- jointed (Fig. 101 and Fig. 102). The close relationship which associates long-jointedness with low- jointedness is easy of comprehension, the pastern becoming less and less a column of support, and more and more an elastic spring in proportion as its length in- creases. We have seen above that the arm of the lever of resistance (weight of the body) elongates and imposes greater eiforts upon the muscles and the ligaments. A spring also gives all the more as it is more elastic and as the pressure which it sup- ports is greater. This is precisely what takes place in a long-jointed pastern, which is at the same time nearly always low-jointed, because it is relatively weak and flexible under the weight and the reactions of the body. Some horses, nevertheless, are exceptions. Either from the great resistance of the fibrous ligaments or the tendons to traction, the mode of articulation of their bones, a greater energy of their muscles, an intensity of action which is more effective from the length of the arm of the lever and the perpendicular incidence of insertion, or, finally, for some other cause, these animals redeem the excess of the length of the pastern, and mitigate the evil effects by a less oblique direction. These instances, however, are rare, which is nothing but natural, as we have just seen. Most authors who define the direction of this region estimate it at about 40 to 45 degrees, in such a manner as to form with the fetlock an angle of 130 to 135 degrees. Vallon and M. Lemoigne are the only ones, to our knowledge, who seem to have measured this inclination with some care upon the living horse or upon the skeleton. Aside from the purely theoretical idea that the pastern should have a direction inter- mediary between the absolutely vertical and the horizontal, it has been believed to be good logic to recommend a mean obliquity of 45 degrees, without perceiving that this argument is faulty, first of all, in its premises, since it is not based upon facts. The mean obliquity, in our opinion, oscillates around 60 degrees upon the horizon, in the anterior members, and 65 degrees in the pos- POSTERIOR MEMBER. 305 terior, which are always more vertical to the fetlocks. An inclina- tion of 45 degrees is not observed in well-formed horses provided with good axes ; it constitutes, on the contrary, a low-jointedness quite marked. Let us now see the disadvantages which accrue from an^excess or an insufficiency of obliquity ; they are of the same nature as those which fol- low an excess or an insufficiency of length. There are several ways of ex- plaining this : Let us first re- gard the pastern as an inclined plane of surface and of segment in the de- composition of forces parallel to the weight. Suppose OS and OD (Fig. 103) are two pasterns of the same length, but unequally in- clined upon the canon OC. From the fact of this inclination, the weight of the body, which we will represent in quantity and direction by the line OR, is decomposed, at the level of the fetlock O, into two forces, one of which is parallel to the phalangal region, and is overcome by its own resistance ; the other is perpendicular to the preceding. The latter is exerted upon the sesamoid bones, and tends to lower the angle of the fetlock against the summit of which the tendons are applied. These two components of the resultant OR are, by constructing the parallelo- gram of forces : for OB, Oe and Of; for OD, Og and OD. They indicate, for each inclination, the role which is intrusted to the bones and the muscles. The sole inspection of the figure shows that with the pastern OB (straight-jointed), the component Of exceeds Oe, and therefore likewise OD, which corresponds to it in the other case. 20 FIG. 103. 306 THE EXTERIOR OF THE HORSE. Therefore the straight joint surcharges the bones and relieves the muscles AM, which antagonize the force Oe, while the long joint favors the bones at the expense of the tendons which it exhausts. The pastern plays a no less important part as a lever, whatever way we examine it. Being still given the two pasterns OB and OD (Fig. 104), of the same length, but unequally inclined upon the canon OC: They form with the great FIG. 104. FIG. 105. sesamoids, A, two angular levers, A OB and AOD, of the second class, whose point of contact or fulcrum is on the ground at B and D, whose resistance, R, is at 0, and whose power, M, is at A. It is apparent that by drawing the perpendiculars BF and DE from the points of contact upon the direction of the force R, that is to say, the arms of the lever of resistance for each of these inclinations, this force will act at the extremity of an arm longer in the case of the low-jointed pastern than in that of the straight-jointed one. The obliquity of the phalangal lever, therefore, obliges the mus- cles AM, whose lever-arm remains invariable, to make more energetic POSTERIOR MEMBER. 307 contractions, in order to maintain the equilibrium of the fetlock which receives the weight of the body, whose lever-arm has augmented. Finally, the results are identical when the animal machine, moving at great speed, strikes the ground at each step of the gait. When the levers AOB and AOD (Fig. 105) are of the second class, the power is always applied at A, the fulcrum is at 0, while the resistance becomes the reactions, DE, BF y of the soil against the weight of the body, whichTare per- ceived at the points B and D. By drawing the perpendiculars OF and OE from the fulcrum, or point of relation, upon the direction of the vertical forces BF and DE, it is found, as in the preceding figure, that the greater the inclination of the pastern the more the lever-arms OE and OF augment at the expense of the arm, OA, of the muscles, AM. This implies that the obliquity of the phalangal region renders the reactions of the soil against the quantity of movement with which the body is animated at great speed more laborious and fatiguing for the tendons. It results from the preceding that the inconveniences of low-jointed- ness are of the same value as those of long-jointedness, and hence it follows that they will be superadded to each other in horses suffering simultaneously from these two defects. The same may be said of the straight and the short-jointed pastern. These conformations, nevertheless, do not offer the same gravity in all services. The long and oblique pastern renders the horse more supple and more pleasant to ride ; it enables him to disperse more easily the violent reaction of locomotion at great speed, and it would be very desirable in the saddle-horse, the driving-horse, and the race- horse, were it not a source of danger to the integrity of the tendons. The short and straight pastern is strong ; it has no very prejudicial influences against heavy-draught services, but it renders the reactions hard and jeopardizes thereby the integrity of the osseous apparatus ; hence it unfits a horse for the riding-school or for fast riding. To recapitulate, numerous disadvantages and sometimes advantages may accrue from a pastern erring in its length and in its direction. If both sides be compared, it will be seen that it is injudicious to extol too much any one of these conformations in preference to that which we have indicated as the beautiful : the long, low, straight, and short joints will always constitute defects. Neatness of Outline and Freedom from Blemish. The pastern is called neat when its skin is thin, the subcutaneous connec- tive tissue rather scarce, the hairs delicate and short ; the bones and the tendons are then apparent in their special form and direction. \ 308 THE EXTERIOR OF THE HORSE. Here, also, neatness is a characteristic of quality and distinction, which the thoroughbred horse presents in the highest degree. Com- mon horses, like the draught-horse, have this region more or less thick, and the hairs of the footlock almost cover its posterior face. It is the custom to cut these hairs in the lighter variety of horses which are somewhat lymphatic and lack in breeding, so as to make the mem- bers appear more slender and render the form and outline of the extremities more apparent. This procedure is not practised in heavy horses, in which these hairs fulfil the rdle of protecting organs against mud and dust. The neatness of outline of the pastern implies, as in the other regions, the absence of diseases and blemishes. Diseases and Blemishes. Many diseases are observed upon the pastern or extend there from other regions : such are contusions, excoriations, superficial wounds of the skin, cuts, fissures, collosities, redema, abscess, grease, lymphangi- tis, fibrous elephantiasis, etc. We will only mention them in passing. However, there are some diseases and blemishes whose seat is entirely confined to the pastern. Let us cite first the effects of halter-cast, a transverse or oblique wound which is occasioned in the fold of the pastern by the friction of too long a strap fasten- ing the horse to the manger. This accident is produced when the animal, in endeavoring to rub the mane with one of the posterior bipeds, or the pastern of one of these with the teeth, carries the posterior member forward, which then becomes entangled in the halter-strap. The latter, strongly tensed by the inverse actions of the neck, which is straightened, and of the foot, which is carried backward, moves to and fro over the skin, whence result more or less profound wounds. 1 Sometimes the animal loses his equilibrium, falls down, and twists the neck, which determines a permanent deviation of the latter. 2 Such a mishap can also be produced under other circumstances, when, for example, the horse is tied to a post, or to a cord with a fetter fixed to one of the anterior pasterns ; when he is cast for the purpose of undergoing a surgical operation ; when he is obliged to eat from the ground, and being in harness, accidentally entangles one of the members in the reins, etc. The symptoms and the gravity of this accident vary according to the qualities of the rubbing body, its hardness, the intensity of the friction, and the nature of the lesions. We will not expatiate on these. Let us merely say that a cicatrix follows these lesions, which, in most instances, is permanent, and upon which the hairs are not replaced. At times, the cica- tricial tissue is so abundant that the region remains permanently enlarged and deformed ; the movement of flexion of the foot is rendered less easy and the skin is much more sensitive to causes capable of irritating and excoriating it. Finally, there are cases in which cicatrization never follows, and the wound con- 1 H. Bouley, Nouveau dictionnaire de m^decine, de chirurgie et d'hygiene ve"te>inaires, t. v. p. 662. 2 This accident, caused by the struggles of the animal, often gives rise to wryneck or partial luxation of the cervical vertebrae. POSTERIOR MEMBER. 309 tinues to discharge. The latter is then converted into an incurable fissure, often with an eczematous condition of the surrounding parts. Fissures on the pastern are more grave than in any other region by reason of the movements and the difficulty of maintaining the wound which they occasion in a proper state of cleanliness. The soft tumors which are observed here are synovial dilatations belonging to the great sesamoid sheath, or to the articulation of the fetlock. They appear on each side of the flexor tendons, but usually do not acquire a large-volume. However it may be, they accompany windgalls, and only show themselves when the latter are largely developed. Linear cicatrices are met on the lateral planes of the pastern, indicating that the animal has been subjected to neurotomy for a chronic disease of the organs contained in the hoof, or for osseous tumors of the coronary region. It is there- fore necessary to ascertain if the malady against which the treatment has been employed has disappeared. Exostoses of the first phalanx receive the name of osselets. Some incor- rectly call them ring-bones, this appellation being reserved for the osseous tumors of the coronet or of the complementary fibro-cartilages of the third phalanx. The osselets may or may not cause lameness, according to the restraint which is experienced by the tendons or the articulation ; they generally result from hard usage, and occur more frequently upon the anterior members, upon short and straight pasterns oftener than upon any others. Sometimes they result from blows, and are even the consequence of fractures of the first phalanx, accom- panied by the formation of a callus. Finally, let us mention traces of actual cautery, in points or in lines, used as a means of treatment against osseous tumors, indurations of the skin, or all other chronic affections of this region. These blemishes are, however, in most in- stances, only an extension of those which are dependent upon the cauterization of the fetlock or the coronet. When they are present, it is imperative to examine with care the adjoining parts of the member in order to assign to these blemishes their just value in the depreciation they cause to the animal. J. The Coronet. Situation; Limits; Anatomical Base. The coronet, a region rather difficult to delimitate, is situated between the pastern and the hoof. Its anatomical base is that part of the second phalanx not contained in the horny case, covered anteriorly by the tendon of the anterior extensor muscle of the phalanges, posteriorly by that of the deep flexor, and laterally by the supe- rior portion of the complementary fibro-cartilage of the third phalanx as well as by the glomes of the plantar cushion. Rounded from side to side on its anterior face, wider below than above in consequence of the presence of the coronary band, and depressed on its posterior face at the level of the concavity which separates the two bulbs of the aforesaid cushion, the coronet also presents on each side the tuberosities which give attach- ment to the lateral ligaments of the first inter-phalangal articulation. It is 310 THE EXTERIOR OF THE HORSE. covered by a thick skin provided with hairs more or less abundant and coarse, according to the fineness of the animal. Before presenting a pleasure-horse for sale, they usually clip his hairs in order to give to the members a certain appearance of lightness. But neither horses of the finer races nor heavy-draught horses are, as a rule, subjected to this practice, because in the former the hairs are short and fine, and in the latter they constitute an apparatus of pro- tection of which it is unjust to deprive the horse. In the army it is prohibited to dress the hairs over the parts cor- responding to the pastern, in order to protect them as much as possible against the injuries so frequent during the manoeuvres. Beauties. The only points of this region are the width, the fine- ness, and the freedom from blemishes. The first implies a correlative width of the phalanges and the firmness of the member. The second consists in the thinness of the skin and the delicacy of the hairs ; it indicates the ancestry, the tem- perament, the energy, and the vigor of the horse. As to the third, it implies a perfect regularity of the parts and the absence of diseases and blemishes. Diseases and Blemishes. The coronet, like all the other infe- rior regions of the members, shows numerous alterations which involve either the skin and the subcutaneous connective tissue, the tendons, or the bones. Their gravity necessarily depends upon the nature of the lesions, their location, their period of existence, and the interference which they offer to the locomotory function. These are first calks, deep wounds of the skin, of a variable extent, which result from the contact of the feet in some circumstances, as on the race-course or in leaping over obstacles, for example. Grease or water in the legs, already cited in the description of the canon, the fetlock, and the pastern, often begins at the coronet, whose hairs it agglutinates into small pencils of a bristly aspect which is quite peculiar, and which is vulgarly compared with a comb. Contusions and other traumatisms produce, at times, deep alterations of the lateral cartilages, the tendons, the glomes of the plantar cushion, or even the skin, and give rise to a partial necrosis of these structures, known under the generic name quitter. A quitter may be tendinous, cartilaginous, or cutaneous, according to the tissue involved. In general, they should be considered as being grave, for they incapacitate the animal from service for a long time and com- promise his very life by the complications which accompany them. (See Foot.) The anterior face of the coronet is sometimes the seat of an affection called crapaudine, which is characterized by a peculiar modification of the secretory function of the coronary band, which becomes fissured and cracked after the manner of the bark of an old tree. (See Foot.) POSTERIOR MEMBER. 311 The osseous tumors of the region have received the name ring-bone, and are located on the anterior and the lateral faces. Clinically, they are distinguished as coronary and cartilaginous, according as they are developed upon the second phalanx or in the thickness of the lateral cartilages of the foot. 1 They are usually, to whichever variety they may belong, the consequence of violent percussions received by the bones during locomotion, or of contusions of the cartilages. They also follow inflammatory conditions of a diverse nature, such as abscesses of the coronet, tendinous or cartilaginous quitter, the prick_of a nail, etc. ; finally, they are frequently sequelae to fractures, in which case it is observed they are persistent. Short-jointed horses, young horses with a precocious consti- tution, which are subjected to laborious work, and full-grown horses which are employed in severe labor on the pavements of large cities are much more pre- disposed to such formations than others. The influence of heredity has been recognized for a long time ; certain families of horses, from injudicious selections or crossing, invariably transmit these blemishes to their descendants. Ring-bones are recognized by a hard, resisting tumefaction, which covers the anterior or lateral faces of the coronary region, and manifests itself as an abnor- mal convexity when the animal is examined from in front or in profile. Although the enlargement is most often apparent to the eye, it is sometimes concealed by the thickness of the integument and the abundance of the hairs ; it is therefore necessary to complete the examination by the use of the hand, especially in horses whose coronet is not very distinct in its outlines. A ring-bone most usually at its beginning occasions lameness ; but when the tumor is once formed the lameness disappears, unless the exostosis has reached the contour of the articular surfaces. Knuckling also appears as a complication of old ring-bones ; to this symptom may be added contraction of the hoof, due to the deviation of the coronary band. These exostoses always constitute a serious blemish, but the degree of the gravity nevertheless varies. It is clear that the depreciation of the value of the animal is greater as he is one of luxury or a rapid motor, and as the interference with the locomotory functions is more pronounced. Many horses are but little depreciated even by a voluminous ring-bone which is not accompanied by lame- ness, or whose lameness does not interfere with their utility as draught-horses. It is entirely different with pleasure-horses, in which the perfectness of conforma- tion and the cleanness of the members form one of the essential conditions of their acquisition. Finally, these exostoses are, from their hereditary tendency, an absolute reason for condemning such horses as are destined for breeding purposes. The coronet rather frequently presents on its surface traces of the actual cautery in points or in lines. We will repeat here the advice we have so often given in such cases : it is necessary to ascertain by a minute examination that the diseased processes against which this treatment has been employed have really disappeared. Certain horse-dealers, indeed, have applied, with fraudulent intent, the actual cautery upon the member for the concealment of a lameness whose seat is more or less distant from the cauterized parts. Let us remark, in terminating, that there is a particular variety of scabies or mange affecting the inferior extremities of the members of the horse ; it is qual- ified symbiotic or chorioptic mange, because it is caused by an acarus named sym- 1 These are ordinarily called side-bones. 312 THE EXTERIOR OF THE HORSE. biotes or chorioptes spathiferus. It resides in the coronary band, the fold of the pastern, and the footlock, which are soon covered by an abundant scurfy desqua- mation of the epidermis and gradually deprived of their hairs. This mange is benign, in consequence of its very slow spreading and the little tendency of the acarus towards migration ; it passes easily from one anterior or posterior mem- ber to the other, whilst it is more rarely seen to be communicated from one anterior member to the corresponding posterior. However it may be, this variety of mange occasions decided itching, which prevails during the night or after work and induces the animal to rub and bite himself. From this symptom, it disturbs their rest, worries them unnecessarily, and exposes them to wounds which are to be dreaded on account* of their situation. It is only contagious from horse to horse, and not at all from horse to man. CHAPTER III. THE FOOT. Definition. The foot, in its relation to comparative anatomy, is all that part of the member which is below the forearm or the leg. This definition, on the contrary, much more limited so far as the exterior is concerned, is here applied only to the extremity of the members which rests upon the ground, the nail, properly so called, the horny box, vulgarly known under the name of the hoof, which contains and protects living, sensitive tissues of variable texture and properties. Distinction. Four in number, the feet are qualified fore or hind, according to their relative situation with the centre of gravity. All have the same general organization; they differ, nevertheless, in several external characters which we will soon explain. In each biped, anterior or posterior, they are distinguished as right and left'; their conformation otherwise is absolutely identical. A. Organization of the Foot. The foot has always been considered as one of the most important regions to study. This will be the better appreciated when we learn the part it plays in station and in locomotion, the influence of its beauties and defects upon the aptitude of the animal for diverse services, and, finally, the gravity of its diseases. More than twenty-two centuries ago, Xenophon said that the mem- bers are the very first parts to be examined in the horse : " A house cannot serve any purpose, however perfect it may be in its superior THE FOOT. 313 parts, if it has not a good foundation ; it is the same with a war- horse ; he will be good for nothing if, being perfect otherwise, he has bad legs (members) ; for he is unable to use whatever good points he may have. " In the examination of the legs, look first at the foot !" l This is the same idea which is reproduced, in our days, in the forms of aphorisms in all treatises on the exterior : " No foot, no horse !" said Lafosse. " No foot, no horse !" repeat the English. Bracy-Clark has only translated the thought of Xenophon when he said, " Incerta basis instabile sedificium !" The foot is formed by a certain number of internal parts, covered by a modified skin admirably adapted to its special functions, as well as by a horny envelope known under the name hoof. Let us examine them rapidly. i. Internal Parts of the Foot. These parts are complex and numerous ; their relation can be clearly recog- nized in a vertical and antero-posterior section of the organ (Fig. 106). Three bones form its osseous base and permit it to accomplish its various movements. These are : the third phalanx or pedal bone (a) ; the second phalanx, or coronary bone (b) ; finally, the navicular, or small sesamoid bone (c), situated behind the preceding and complementing the articulation which the other two form. Short, strong ligaments consolidate the joint on the sides, while two wide fibre-cartilaginous plates, lateral cartilages of the third phalanx, intimately united to this bone, seem like two elastic and diverging springs, placed on the outside and on the inside of this bone, to prevent it from descending or rocking too sud- denly in the hoof at the moment when the latter strikes the ground. Two strong, expanded tendons terminate upon the third phalanx : the anterior (d) carries it into extension; the posterior (e) permits, on the contrary, the flexion of this bone upon the os coronse ; it glides over the inferior face of the navicular bone by means of a synovial sheath designated under the name small sesamoid sheath (better called the navicular sheath). Finally, a voluminous fibro-elastic cushion (g), called the plantar cushion, bifurcated behind and pointed in front (Fig. 107, B : c?), is placed under the flexor tendon, to which it serves as a flexible buffer when the foot has reached the ground. All pressure upon the hoof from below upward tends to depress it and force it against the lateral parts, where it is maintained by the two elastic carti- lages indicated above. Cutaneous Envelope of the Foot. This is the skin, modified in its functions and external characters, which covers the surface of all these organs. The proof of this can be easily obtained by maceration of the hoof, or the arti- ficial removal of the hoof and the hairs of the digital extremity, in order to see 1 X6nophon, De 1'Equitation, traduction du baron de Curnieu, chap. i. p. 7. Paris, 1840. 314 THE EXTERIOR OF THE HORSE. the integuments in direct continuity with the living parts which might, at first sight, be mistaken for tissues consisting of an entirely different organization. Let Fig. 107 represent, by A, the normal foot before maceration ; by B, the same FIG. 106. Longitudinal and median section of the foot. foot after prolonged soaking in water. The epidermic productions, the horn and the hairs, naturally detached, leave the cutaneous covering intact. The latter, vulgarly known under the name fleshy envelope, flesh of the foot, is remarkable for its great vascularity and the abundance of its nerves. Hence it is very susceptible of congestion and inflammation as soon as the hoof, which surrounds it, has lost its physiological properties. All its lesions, of whatever nature they may be, are always accompanied by intense pain, the tumefaction of the living parts becoming impossible, incased as they are in a resisting, almost inextensible, envelope. THE FOOT. 315 The cutaneous envelope of the foot, also called the keratogenous membrane, is subdivided into three important regions. These are : a. The coronary band or cutidure (Fig. 107, B : a) is an enlarged, cir- cular band or ridge, crowning superiorly the living parts and terminating behind B A FIG. 107. A. The normal foot before maceration. B The foot after maceration. by a continuity with the glomes, c, of the plantar cushion. It offers along the entire length of its superior border a much smaller secondary convexity, known under the name of perioplic band, to which are intrusted special functions. It is covered over the remainder of its surface by a multitude of filamentous prolongations, papillae, easily perceived when immersed in water. These pene- trate, by so many foramina, the superior border of the wall. Endowed, physio- logically, with the elaboration of the latter, the cutidure constitutes also, by its villosities or papillae, very rich in nerve filaments, a veritable organ of tactile sen- sation for the horse, which can thus recognize, with all the perfection desirable, the quality of the surface upon which his foot rests. b. The podophyllous, laminated, or lamellar tissue (Fig. 107, B:b) comprises the whole periphery of the cutaneous envelope situated below the coro- nary band. This tissue, which owes its name to the numerous laminae or longi- tudinal leaves which it presents, also forms a whitish, soft horn, composed of 316 THE EXTERIOR CF THE HORSE. laminae intimately united to the horn which descends from the coronary band. This adherence of the two horny productions is so strong that it resists the most prolonged maceration. Behind, the lam- inae are reflected into each of the lateral lacunae of the plantar cushion, and are in relation with that part of the parietes of the hoof which is called the bars. c. The villous or velvety tissue (Fig. 107, B : d), whose aspect approaches that of a bushy sod, in consequence of the innumerable villosities over its sur- face, covers the whole of the plantar sur face of the third phalanx and the plantar cushion or fleshy frog. Like those of the cutidure, these papillae are received into the numerous foramina of the subjacent horn which is produced by the most superficial layer of the velvety tissue. 2. The Hoof. The hoof, as we know, is the exter- nal horny envelope of the foot, or, more properly speaking, the nail of the horse. Its form is that of a cone with its base downward and the summit truncated obliquely from above to below and from before to behind (Fig. 108). Its conical disposition, however, being always very slight, is only very apparent when it is examined from in front or behind. Viewed in profile, it has more the form of a cylinder, as has been remarked by Bracy-Clark l (Fig. 109). Concave below, cleft behind, and bordered superiorly by the skin of the coronet, the hoof is composed of three distinct pieces intimately united to one another. These pieces can be separated the one from the other by prolonged maceration or boiling; they are designated under the names watt, sole, and frog. We must enter into a special study of each in order to understand the mechanism well. a. The Wall. The wall or paries forms, as its name indicates, the circum- ference of the hoof, and includes all that portion of the horny case which is visi- ble when the foot rests upon the soil. It represents a large crescent of horn, curved on itself (Fig. 110), placed against the anterior face of the foot on which FIG. 108. Foot viewed in front. 1 Bracy-Clark, Recherches sur la construction du sabot du cheval. THE FOOT. 317 it is moulded, and folded from behind forward at its extremities. The latter ter- minate in a point, converge towards each other by en- circling the frog, and unite at the point of the lat- ter. 1 The wall is divided into sev- eral important re- gions bearing vari- ous names (Figs. 109 and 111). The toe, a, is the median and anterior fifth of the circumference. The mammas, b, include the fifth on each side of the toe. The quarter, c, also double, constitutes the posterior fifth of the lateral sur- FIG. 109. Profile of the hoof. 1 FIG. 111. Inferior face of the hoof. k face, immediately behind the preceding. x The heel, d, situated altogether behind, corre- c sponds to the point where the wall becomes inflected inward to constitute the bars. Finally, the bar or stay, e (Fig. Ill), visible only on the raised foot, is the re- flected portion representing the extremities of the wall, placed between the frog and the sole. The wall offers for study, also, besides these subdivisions, two faces and two borders. The faces, distinguished as external, e (Fig. 109), and internal, q (Figs. 112 and 113), diminish gradually in height from the toe to the extremity of the bars. 1 This statement is entirely erroneous, because the bars do not extend beyond tbe posterior two-thirds of the lateral faces of the frog, which I have repeatedly observed. (Harder.) 318 THE EXTERIOR OF THE HORSE. The first, convex transversely, rectilinear from above to below, is smooth, polished, and shiny. It is more oblique anteriorly than on the sides, which are themselves unequally inclined and incurvated. The internal quarter is always more straight and less round than the external. The second, concave from side to side, is covered by numerous longitudinal laminae, q, of white horn (ker aphyllous tissue), which are solidly dovetailed into those of the podophyllous laminae on the pedal bone. As to the borders, the inferior (Fig. Ill), the longest, rests upon the ground, whose friction and wear it sustains, particularly at the toe and the mammae, in the unshod foot. On the con- trary, bearing upon the superior face of the shoe in the domesticated horse, this border is removed by the farrier at each shoeing ; and the latter should, in this connection, endeavor to imitate the natural condi- tions of wear and tear. Its thickness diminishes from the toe to the heels, and then augments sud- denly at this point to form the bars. Finally, it is intimately united along its whole periphery to the contour of the sole. The superior, thin and oblique, shorter than the preceding, and bounded ex- teriorly by the periople, p (Figs. 109 and 117), is transformed, inwardly, into a semi-cylindrical gutter, g (Figs. 112 and 113), which traverses its entire length and lodges the cor- onary band. It is at the region of this gutter, called the cutigeral cavity, which becomes effaced towards the region of the bars, that the parietal horn is elabo- rated by the cutaneous thicken- ing in question. b. The Sole. The sole is a large horny plate (Fig. Ill), deeply notched behind for the FIG. 112. Antero-posterior and vertical section of the hoof (internal face). in D FIG. 113. Transverse section of the hoof (anterior part). reception of the frog, which oc- cupies the inferior face of the foot. Concave inferiorly and convex superiorly, it fills the interval which exists between the inferior border of the wall, the bars, and the point of the frog. Its superior or internal face (Fig. 114, a) is studded with porosities in which are embedded the numerous papillae of the velvety tissue, and receives the pressure of the third phalanx. The inferior,/ (Fig. Ill), excavated, arch-like, and in contact only with the inequalities of the ground in the wild horse, is hard, dry, and scaly. THE FOOT. 319 Of the two borders, the external or anterior describes almost a semi-circum- ference, and unites intimately with the inferior border of the wall. The internal or posterior, on the contrary, much less extensive, simulates a re-entering angle, like the letter V, whose sides are adherent to the bars and the frog. c. The Frog. The frog is a wedge or pyramid of soft horn, which covers the plantar cushion, whose form it reproduces. Lodged in the angle formed by the bars and the posterior border of the sole, it is seen to be single in front and bifid behind; two faces and two extremities are thus assigned to it. The superior or internal face, b (Fig. 114), is the reverse of the in- ferior face of the plantar cushion; it presents, consequently, a marked relief on the median line, known under the name frog-stay, m (Figs. 113 and 115), and on each side two gutters, n, n, converging in front, which respond to the branches of the plantar cushion. Like the sole, it is covered by a large number of perforations, which receive the cor- responding villosities of the velvety tissue. The inferior or external face (Figs. Ill and 116), much more important with regard to the exterior, is hollowed in its middle by a cavity, h, called the median lacuna, separating the two branches, i, i } from each other. Between each branch, i, and the bar are the lateral lacunae, j,j (Figs. Ill, 113, and 115) ; finally, the body of the frog is the point of juncture of its two branches. In the wild state, the inferior face of FIG. 114. Interior of the hoof. e j i h i j e FIG. 115. Transverse section of the hoof (posterior part). FIG. 116. Frog and periople. the furuncular branches, in conditions of nature, is upon the same level as that of the heels and the bars; it consequently rests upon the ground, as can be 320 THE EXTERIOR OF THE HORSE. readily observed by the examination of the transverse sections represented in Figs. 113 and 115, practised upon unshod feet. The frog, at its anterior extremity, terminates in a point (Figs. Ill and 116), which is lodged in the sum- mit of the re-entering angle of the sole. Its posterior extremity bifurcates and terminates by two enlargements, o, o (Figs. 109, 116, and 117), called the glomes, which overhang the heels and become con- tinuous along the superior border of the wall by a thin, soft, flexible band of horn, jo, little pervious to water. "The latter produc- tion, known under the name of periople, and secreted by the perioplic band of which we have already FIG. 117. Hoof whose perioplic band is detached. FIG. 118. Fore-foot. A' Profile. B. Posterior view. C. Inferior face. spoken, is nothing else than the prolongation of the cutaneous epidermis upon THE FOOT. 321 the hoof, for which it forms a sort of protective varnish against the variations of dryness and moisture. Such is, in a summary manner, the anatomical construction of the foot of the horse. Let us now see the peculiarities concerning this organ if it be examined in the two sorts of members. Differences between the Fore- and Hind-Feet ; the Left and the Bight. These differences are secondary, altogether super- ficial, and do not modify the preceding details which bear on the general organization. The fore-foot (Fig. 118, A, B, C) is more round, more spread out, less concave, and a little wider than the hind; the heels are less separated ; the wall, in profile, is more oblique ; the frog is less long, but more voluminous, thicker, and closer to the ground. B A FIG. 119. Hind-foot. A. Profile. B. Posterior view. C. Inferior face. The hind-foot (Fig. 119, A, B, C), on the contrary, is oval, con- cave, with higher and more separated heels, and a more vertical wall ; the branches of the frog are less thick and more separated ; the bars, finally, are somewhat stronger. Nothing is more easy than to distinguish a left from a right foot, 21 322 THE EXTERIOR OF THE HORSE. whether they belong to the anterior or the posterior biped : the external side of the wall is constantly more inclined and more convex than the internal ; also, the inferior border of the wall is always rounder and stronger on this side than on the other. B. Properties and Mechanism of the Foot. The foot of the horse, such as we have described, is an organ which enjoys certain properties inherent both to the nature and disposition of the tissues which compose its internal parts and to these same qualities possessed by the horny envelope. It is on account of these properties that the foot can fulfil, with all the desirable perfection, the important functions which devolve upon it. The Horn : Properties. The horn is a hard, compact, resisting, elastic, and tenacious substance, which is softened by contact with water or the influence of dampness, and hardens by evaporation. It is very combustible, and gives origin, when burning, to abundant fumes of a characteristic odor and a carbonaceous adherent matter which protects the living tissues against the action of the heat. a. Origin. The diverse regions of the cutaneous envelope (kerato- genous membrane, flesh of the foot) of the foot do not contribute in the same manner to the formation of the horn. As our colleague, M. Arloing, 1 judiciously remarked, some are keratogenous and others keratophorous. Upon the first (coronary band, velvety tissue, perioplic ring) is imposed the elaboration of the nail, properly so called ; upon the second (podophyllous tissue) more particularly devolves the role of support, consolidation, and union. Analogous to a sort of physiologi- cal cement, the latter establishes the relation and adherence between the horn and the living parts. Its production is represented for this pur- pose by the white, horny laminse situated on the deep face of the wall, to which we have made reference above under the name keraphyllous tissue. Thus the wall, the sole, and the frog are formed by the keratogenous regions of the ungual matrix. b. Structure. Under the microscope, the horn appears consti- tuted by a great number of parallel tubes, rectilinear (wall, sole) or undulating (frog), which originate from the vascular papillae of the cutidure or the velvety tissue by enveloping them in the most intimate manner. Altogether comparable to hairs of a large calibre placed side by side, these tubes are composed of a multitude of horny (epithelial) i S. Arloing, Foils et Ongles, these d'agre"gation, 1880, p. 111. THE FOOT. 323 cells, disposed concentrically around the axis in numerous layers in an imbricated manner. The most superficial of these layers affect a dif- ferent disposition : the cells become perpendicular to the direction of the tube instead of remaining parallel, and in this manner is formed the intertubular horn, a veritable cement substance which agglutinates the hair cylinders to one another. c. Color. The horn cells, being epithelial in nature and jformed from the cells of the epidermis of the skin, the hoof assumes a white or black coloration according as the parts which form it are or are not provided with pigment. When the skin of the coronary band is red, the wall is white for an equal extent ; in the opposite case, it remains black. The same considerations are applicable to that of the sole and the frog. , d. Consistency. The consistency of the nail is in direct rela- tion with the degree of humidity of the horn, and this humidity is obtained by the foot either from the surrounding atmosphere or from its own tissues. The temperature of the soil, the quality of the pasture, the hygro- metric state of the air, the season of the year, the nature of the climate, are so many causes whose influence is evident and which it is needless to dwell upon. Likewise, the horn becomes more supple and softer as it is exam- ined closer to the living tissues ; it is, on the contrary, more resisting, brittle, and difficult to cut as it is more distant. The superficial parts of the frog, the sole, and the wall, the inferior border of the latter, are always excessively dry compared to the deeper parts of these structures. These diverse conditions of the hoof, when existing in extremes, offer serious evils from the double point of view of the preservation of the foot and the use of the animal. We will revert to this in the chapter on defects. Growth and Wear of the Hoof. New layers of horn are incessantly secreted at the level of the villous papillae of the kerato- genous apparatus, pushing down the older layers to repair the loss occasioned by use. It is clear that each portion of the hoof grows according to the direction of its own fibres : the wall in its height, the sole and the frog in the sense of their thickness. This growth is effected slowly. It requires about eight months for the production of a completely new hoof. All loss of substance to the wall is therefore reproduced very slowly ; whence the lesson is taught that we should avoid this loss as much as possible. 324 THE EXTERIOR OF THE HORSE. In the wild horse the continual growth, always compensated by a proportional loss from wear, does not induce a deformity of the nail but the case is different in horses which we utilize as motors, on account of the shoe, which restrains the elasticity of the foot and disturbs the normal growth of the hoof. In such cases the wall may acquire an excessive length if the farrier does not take the care to shorten the whole extent of its inferior border to the limits required by the natural wear. As to the sole and the frog, their mode of exfoliation is such that their thickness never becomes excessive ; they become dried, cracked, and peel off spontaneously in more or less voluminous scales. The secretion of the horn is exaggerated by certain influences, as the external temperature, the state of health or of disease, the nourish- ment, etc. We know that the process is more active in w T arm than in cold countries, in summer than in winter, in the healthy animal, abun- dantly nourished, than in the diseased animal, suffering from bad hygiene and an insufficient alimentation. This is so true that the hoof itself often testifies, by the unequal zones of which it is the seat, of the physical conditions or suffering which the horse has endured. Certain rammy or circled hoofs have in most instances no other origin. Elasticity of the Foot. The digital extremity of the equidse, below the pastern, is disposed so as to disperse or break the con- cussions and the pressure which it receives during locomotion at the moment when the body, at great speed, comes in contact with the ground. Not only is the quantity of movement with which the body is animated dispersed and decomposed by the inclined planes of surface and of segment, but it is destroyed also by the intervention of the elasticity of several organs which we will recognize. It is there- fore already considerably lessened when it arrives at the hoof, where it meets several elastic apparatus, whose mode of functional activity we must rapidly review. These apparatus are : the perforans tendon, the lateral cartilages, the plantar cushion, and the diverse parts of the nail (the wall, the sole, and the frog). The first effect of the contact of the foot Avith the soil is the dis- placement of the third phalanx from above to below in the interior of the horny covering (Fig. 106). This movement of the bone is coun- teracted by the mechanical action of three very evident causes : ante- riorly and peripherally, by the adherence of the podophyllous and keraphyllous tissues ; above and laterally, by the resistance of the lateral cartilages ; finally, below, by the presence of the plantar apo- neurosis and the plantar cushion. THE FOOT. 325 The remarkably solid union between the hoof and the sensitive tissues is due, above all, to the intimate dovetailing of the sensitive laminae with the horny laminae. 1 These two sets of laminae, however, are not simply placed in juxta- position in a parallel manner,' but they interdigitate with one another by the numerous secondary prolongations which they offer on their lateral faces and which are disposed after the manner of the barbs of a feather upon its stalk. This construction admits of a very slight gliding of the keraphyllous laminae of the wall upon those, soft and flexible, of the podophyllous tissue, whence, in consequence, the first decomposition of force at their level. Besides, the wedge formed by the third phalanx not only descends parallel to the wall, but describes a sort of vertical rotation, from the pressure transmitted by the second phalanx to the navicular bone. This pressure is first exercised upon the plantar aponeurosis, e, which maintains the articular angle, and, secondly, upon the elastic plantar cushion situated immediately below. Following this, there exist also at this place two new structures whose elasticity, now called into activity at the moment of the contact, notably diminishes the intensity of the reactions. But the phenomena do not cease here. The plantar cushion, strongly compressed from above to below by the weight of the body, tends to depress the plantar arch at the same time that it elongates transversely, where it is maintained by the two lateral cartilages. The latter, flat, wide, supple, and very elastic, overlap behind the superior border of the wall and sensibly separate from each other under the influence of the eccentric pressure which they receive from the plantar cushion. They are therefore opposed, in their turn, to the rotation of the third phalanx in the interior of the hoof. Thus, little by little, the internal parts of the foot decompose the reactions of the weight, by changing their form and relative situation, and, finally, by concentrating their action upon the diverse parts of the hoof, especially the frog, the quarters, and the sole. The sole is flattened and becomes less concave inferiorly ; its 1 M. Fader has recently called attention to the remarkable manner in which the horny case is attached to the living parts. According to him, in a horse of medium form, the laminae of the foot being supposed to have an area of a square decimetre, the total surface of the principal and secondary laminae, which he has had the patience to compute, should attain about one square metre ! It can then be readily understood how this system of dovetailing of the laminae is cal- culated to insure the intimate union of the horn and the flesh, to decompose the concussion, at times enormous, which the ungual extremity receives, and to distribute uniformly the pressure upon the whole of the internal face of the wall. (See, for more details, Bulletin de la Soc. cent, de med. vet