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Les diagrammes suivants illustrent la mithode. 1 2 3 32X 1 2 3 4 5 6 Uup. 0) 3-?/- 3d Xoo\ J?A7, "2.oo\ ^ A THE INTERNAL PARASITES OP THE HORSE. '/ / (ENTOZOA.) BY I J. T. DUNCAN, M.D., CM, V.S., LECTURER ON THE ENTOZOA OF THE DOMESTICATED ANIMALS IN THE ONTARIO VETERINARY COLLEGE ; HONORARY ASSOCIATE OF THE R. C. V.S., LOND.; MEMBER OF THE ASSOCIATION OP AMERICAN ANATOMISTS, ETC. ILLUSTRATED. Toronto, presbyteeian news co. 189I. THE WllU^^^^O^^ ^^^^ ^°' 35 a* 10 Ve- Entered according to Act of Parliament of Canada, in tha year 1891, by J. T. Dunc/n, in thi office of the Minister of A^friculture, Ottawa. PREFATORY NOTE. I i! In teaching this subject, the want of a suitable text book has often been felt. Cob- bold's small volume has been difficult to obtain, Iwhile the larger works are too voluminous. In attempting to supply the need spoken of, the labor of the writer has been principally that of a compiler. The works of Cobbold, Leuckart, Robertson, Fleming, Williams, Law, and others have been drawn upon. In addition, the ex- perience of many Veterinarians has been availed of; the cases reported by them being exceedingly instructive. These ma- terials having been arranged in such a man- ner as to facilitate reference, it is hoped that the result as presented in the follow- ing pages will be found useful to the Veterinarian and horse owner. J. T. D. Toronto, 1891. B CONTENTS. Section I. — General Considkrations. Pef/<)//a/a and T. plicata .. 29 Symptoms 30 Epizooty in Wales 30 Post Mortem 31 Diagnosis 32 Prognosis 32 Treatment 32 Section IV. — Np:matoi)e.s, or Round Worms. Sub-Section i. — A scan's megalocephala. Form 34 Length 34 Habitat 35 Numbers 35 Development 35 Symptoms 36 Burneson's Case ....*. 37 Cases in England 38 Diagnosis 39 Prognosis 39 Preventive Treatment 39 Medicinal Treatment 39 Oil of Turpentine 39 Santonin 40 Prof. Robertson's Treatment 40 Tonics — Diet 42 Sub-Sect ion 2. — Oxyuris curvula. Form 43 'I I rape. Length . . 43 Habitat 44 Numbers 44 Development , 44 Symptoms 44 Diagnosis 45 Prognosis 45 Preventive Treatment 4^ Medicinal Treatment 4^ Enemata 47 Diet 47 Sub-Section j. — Filaria papulosa, or F. oculi. Form 48 Habitat 48 Numbers 49 Development 5° Symptoms 5° Diagnosis 5 ^ Prognosis 5 ^ Preventive Treatment 5 ^ Surgical Treatment 52 Mariott's Case 52 Danger of Delay in operating 53 Cocaine as Anaesthetic • 53 Filaria oculi attached to Iris 53 Sub-Section 4. — Strongylus armatus, or Sdtrostomum equinum. Strongylus armatus, Major and Minor 54 Most Important of Round Worms 54 > VI Form — Lengih 54 Habitat 55 Numbers 55 1 )evelo{)ment 55 In the Stomach 56 Immature in Coats of Vessels 56 Aneurisms 56 Symptoms if in the Intestines 57 Symptoms if Wandering 58 Symptoms if in the Coats of Vessels 58 Aneurism, Cause of 58 Aneurism, Pathology of 58 Rupture of Aneurisms 59 Colic Caused by Aneurisms 60 Lameness as a Symptom 63 Miller's Cases 63 I )iagnosis 65 Embolism of the Iliac Artery 65 Prognosis ... 66 Preventive Treatment 67 Medicinal Treatment 67 Sub-Section ^.—Strongylus tetracanthus. Mistaken for St. arniatus Minor 68 Form — Length 68 Habitat 68 Results when in the Intestinal Wall 6q Numbers 69 I )evelopment 69 Symptoms 70 1 1 \ VII. Paoe. Paralysis Caused by S/. teiracanthus 70 Taylor's C'ascs 70 Slocock's Case 73 Post Mortem Examination 74 Epizooty Caused by this Parasite 75 Rees Loyd's Cases 75 Diagnosis 76 Prognosis 76 Preventive Treatment 77 Medicinal Treatment 77 Professor Williams' 'I'reatment 78 Sub-Section 6. — Spiroptera tne^i^astoma. Form — Length 78 Habitat ... 79 Numbers 79 Development 79 Symptoms 79 Sperioptera microstoma 80 Size 80 Habitat 80 Section V. — Trematodes, or Fluke Worms. Fasciola hepatica 80 Size 80 Form 80 Habitat 80 List of the common Entozoa 81 Numerous " Guests " in " Hosts " 82 Fuix List of Entozoa ' 82 VIII. / Section VI. — Bots. Page. Form — Size 84 Numbers 85 Development 85 Position in Stomach 86 Position in the Intestines 86 Escape from the Bowels 86 Summary of Life History 87 Symptoms 87 Effects 87 T. Tegg's Case 88 Tetanus, Caused by 89 Bots in the Pharynx 89 Diagnosis 89 Prognosis 90 Preventive Treatment 90 Medicinal Treatment 90 General Symptoms of Parasitism 92 Illustrations. Figs. I. to v., to face page 94 Figs. VI. to X., to face page 96. Erratum. Page 61, line 14 from the top, read "one hundred" for "forty." Section I. GENERAL CONSIDERATIONS. It is a truth that the older countries are much more liable to parasitic diseases than are the newer. For instance, extensive outbreaks of these diseases are recorded in Europe, India and other eastern coun- tries, while in America we are only begin- ing to notice such attacks. So noticeable is this difference that a general rule may be thus given, ** the older the country the more numerous the parasites." Fortunately for our stock owners, this continent is as yet only to a small extent infested with parasites, but year by year the trouble is becoming more extensive. New districts are infected, a greater num- ber of animals are attacked. The reason for this mainly is that troubles of such a nature are overlooked or neglected. Means are seldom taken to prevent our valuable animals from becoming " hosts " to these unwelcome guests. 12 Parasites of the Horse. So long as this state of indifference con- tinues, so long will loss from this cause gradually increase. This loss, in many cases, will not consist in the death of the animals. Comparatively few will succumb to the attacks of the parasites, but many will be weak, poor and unthrifty in spite of the best supply of food that can be given. The cause may be unsuspected, the owner may be adopting every means known to him to get his animals in condition, but without success* The loss on the fodder, the loss on the animals when sent to market out of condition, these are in many cases greater than if the animal had quickly suc- cumbed to the infection. If these losses are to be prevented, or reduced to the lowest point possible, and if this continent is not to become largely in- fested with these lower forms of animal life, it will be due to the well directed efforts of veterinarians, practical men, men of educa- tion and ability, who are now to be found in every part of the country. The parasites attacking the domesticated Parasites of the Horse. 13 animals either infest the outer parts of the animal, or obtain access to the intestines or other internal parts. This gives good ground for separating them into two great classes, viz. : Ectpzoa, so named from two Greek words meaning ''without" and "ani- mal," and Entozoa, which is similarly from the Greek '*ento" within, and "zoa" animal. The ectozoa then are the external parasites, such as lice ; the entozoa are those which are internal, such as tape worms. In this work there is no reference to the ectozoa, it is wholly devoted to consideration of the entozoa, and it is to this class of parasites that the previous remarks are more es- pecially applicable. Causation and Development. — The study of parasites, first, in regard to their origin, and then in regard to their life his- tory, has presented great difficulties. The total dissimilarity which so many of these present at different periods of their exist- ence particularly has rendered the study most puzzling. Of late years, howeveiv great progress has been made. Erroneous 14 Parasites of the Horse. theories have been swept away, and facts have been discovered and verified to such an extent as to place the study now on a sure basis, although much has yet to be accomplished before the life history of all parasites is understood. Before proceeding to discuss particularly the entozoa of the horse, some of the more general truths in regard to parasitism may be set forth. Some years ago the doctrine of ''spon- taneous generation " was held in regard to the entozoa by many scientific men. In other words, they held that the origin of these parasites was without cause ; — did not require any pre-existing ova or seed. But this theory is now entirely given up. Numerous observers and experimenters have proved beyond a doubt that these, as well as all other organisms, are always developed from ova. There is, indeed, no such thing as "spontaneous generation." Speaking now of round worms, their ova, or eggs, being formed in the parent worm, and passed from it into the intestine of the A Parasites of the Horse. 1 5 "host,"^ will not form an embryo while located there. They must escape from that position before they can pursue their round of existence. It may indeed be given as a general law that the eggs must be passed away with the faeces from the animal before the embryos will develop. Having escaped from the **host," and fallen upon damp earth or near a pool of stagnant water, embryos soon appear, and often these embryos swim about freely in the water near which they were dropped, growing and developing the while. For the most part, these embryos need to enter the body of some other animal before they can continue their life history. Suitable creatures are. found in the soft- bodied water snails, which are so often seen in stagnant water, and into these the embryos pass. Having found in them a suitable resting-place, they here encyst themselves, and, if the snail in which they * The term "host " is applied to the animal which carries the mature form of the parasite. " Intermediary bearer " is used to indicate the animal bearing the immature form. i6 Parasites of the Horse. now reside be not swallowed by another animal, the embryos will die a natural death after a time. On the other hand, a horse may, in drink- ing of the water in which they are, or eating the grass around the pools, swallow the snail containing the embryo parasite. The snail, having been thus swallowed, its soft body is soon dissolved by the active fluids of the stomach (gastric juice), and the em- bryo is set free. Not so easily destroyed as the soft-bodied snail, this embryo is gener- ally carried into the intestine, where it finds a suitable resting-place. There development takes place with more or less rapidity, the v/orms attain maturity, and, male and female being present, fecundation takes place, thus completing the life history. ''^ In regard to the tape- worms, t the sexes *While the above may be accepted as a fair statement of what is held by the majority of helmiothologists, it is proper to say that excellent authorities differ widely from them. Thus, Davaine holds that nematodes do not need an inter- mediary bearer, although they certainly migrate from one host to another. t Tape-worms— resembling a tape in appearance. See page 2b Parasites of the Horse. 17 are not distinct. Each segment, indeed, possesses male and female organs. The male organ belongs to the dorsal surface, or back of the segment, the female opening (vagina) to the ventral. Sometimes both of these organs are close to the edge of the seg- ment. Copulation takes place by the in- troduction of the male organ into the vagina of the same segment. The de- velopment of the ova proceeds rapidly, and the uterus becomes crowded with them, so much so as to show very prominently its outlines when a ripe segment is examined. These segments, when they become thus full of eggs, are being constantly passed off from the parent worm (which lies anchored to the mucous membrane of the intestine of the animal), and come away with the faeces. Dropped upon the pasture, or in the stable, they are broken up, and the ova scattered far and wide. These, in food or water, are conveyed to the intestine of another animal (intermediary bearer), where the eggs are hatched out, the embryos escape and wan- der free in the intestine. But not long do i8 Parasites of the Horse. they thus wander. In this intermediary bearer they are immature and must find some place in which they can rest before proceeding in their development. These embryos pierce the walls of the intestine, and wander through the tissues until they arrive at the proper place. What a curious instinct — if it may be called so — it is which leads these embryos to certain definite localities of the body. Thus, one species does not rest until it reaches the brain, an- other is not satisfied outside of the liver, while still another prefers the muscles of the host. Whatever locality it may be that the individuals of the species desire, they wan- der till they reach it, then form there a ** limited settlement " or colony. Having reached this resting-place de- velopment goes on, and soon a minute tape- worm head is formed. In addition to the head, a rudimentary neck appears, and these parts are both enclosed in a bladder, which really represents the caudal appen- dage, or tail. The head and neck are not properly " inclosed " in the bladder, but are Parasites of thb: Horse. 19 surrounded by it, and may be protruded from it* These little bladder worms, consisting, as has just been said, of a little sac filled with fluid (serum) with the head and neck of the future tape worm pressed down into it, are often spoken of as cysts. But they are not usually left without an additional covering, for the connective tissuet of the organ in which they lie forms around them a cap- sule, very thin at first, but gradually in- creasing in thickness until it is well marked. Here then we have the future tape worm as yet immature enclosed in a capsule, and supplied with nourishment from the small vessels which go to its capsule. But al- though thus enabled to develop slowly, it is only if some other animal should eat the infected part of this intermediary bearer, that the embryo can become mature. I f, however, it is so taken, the gastric juice of the animal which has swallowed it dissolves off its cap- *In' this matter I follow Moniez, not Leuckart. diagrams, Figs 12 and 13. ^Vide Leuckart, page 359. See JO Parasites of the Horse. ) sule, the caudal appendage disappears, and the now freed head passes to the intestines, where it anchors, and proceeds to throw out the segments of which we have previously spoken. In this position the parasite re- <:eives no nourishment from blood vessels, nor by devouring the mucous membrane on which he merely holds. The nourish- ment here is from the intestinal juices, which are often so abundant as to permit us to say that the tape- worm ''swims" in them.^ The head holding its position, there is growth by segmentation of the neck," (Leuckart), the earlier developed of these segments being constantly pushed further from the head by the development of new •ones. The segments are at first without sexual organs, but gradually these appear, the male organ first, being dorsal in posi- tion, and then the female, which is ventral. Each segment having now both male and female organs, impregnation takes place, * Vide Leuckart. — These remarks in regard to the nourish- ment of tape-worms in the intestines apply also to nematodes in the same position. PARASITtS OF THE HORSE. 21 and the round of life history is complete. Before proceeding with a notice of the separate parasites, one can not but be im- pressed with the provision which nature has made; on the one hand to ensure the propagation of every species, and on the other to guard against the excessive multi- plication of parasites. On the one hand we see provision for propagation by the enormous fecundity of nematodes, some females bringing forth sixty-four millions of eggs, or ova annually.* Undue multiplication is guarded against in several ways. In the first place the ova must pass from the host in order to de- velop, and many millions of these ova perish by being dropped in a dry pasture *We may givfe this instance of remarkable fruitfulness in addition to that of the nematodes (mentioned above). In Tance it is stated that many of the cases resulted fatally. In one instance twelve hundred of these worms were counted, and in a similar fatal case Mr. Lewis reports that he found the small intestines literally crammed, some thousands of worms being huddled together in large masses. Parasites of the Horse. 39 r Diagnosis. — Usually this is easy, as the animal has generally passed several worms before being brought for treatment. Also, the symptoms are fairly well marked as a rule. Certainty, except in rare cases, can be attained by the administration of a cathartic and examination of the faeces. Prognosis. — Favorable. Treatment. — Preventive.-CohhoXd says, " So long as the water supply is good, and the fodder clean, there is no possibility of infection." Especially should horses be prevented drinking from foul road side pools. Treatment. — Medicinal -T\i^ diagnosis having been made, the bowels(if not already empty) must be cleared before administering a v^ermifuge. This may be done by a suffi- cient fast (over night) and an aloetic ball. The vermifuge must then be adminis- tered in the morning, before any food is given. If oil of turpentine is the vermifuge selected, a drench composed of that medi- cine ; one to two ounces in a pint of gruel or raw linseed oil may be carefully given, 40 Parasites of the Horse. followed in the course of an hour by a bran- mash, on account of its laxative character. (Indeed, for the few days the animal is under treatment, hard food should be avoided ; mashes, boiled barley, carrots, etc., may be substituted.) The turpentine and oil may be repeated on the second, or even on the third morn- ing, if necessary, followed in twenty-four hours by a moderate purge of aloes and calomel. Santonin in half, or one drachm doses, made into powders with linseed meal may be given for two or three mornings in suc- cession, followed by a cathartic, using the precautions above stated as to diet, etc. Professor Robertson speaks highly of the following combination : — R Pulv. Antim. Tart, . . . .ij4 drachms. Hydrarg Submur, .... J^ drachm. 01. Filix Mas. Ol. Sabinse aa i drachm. Pulv. Zingiber, i drachm. Terebinth Venet, q. s. Ft. bolus. ; ^ Parasites of the Horse. 41 1 S. — One to be given for two or three mornings in succession, followed by a laxa- tive if purging does not ensue. In many cases it will be found that the second ball causes purging and nausea, in that case the third ball, or a laxative, should be withheld. Many other vermicides and vermifuges might be mentioned, but there are few cases in which either of the above three methods of treatment will not be successful. The first is the most commonly used, and is exceedingly successful in the majority of instances. The second method (by santonin) has this advantage, that it is more easily given than turpentine. Santonin is nearly taste- less, therefore the animal will rrcen take the powders in his mash. It is very de- structive to round worms. Professor Robertson's method of treat- ment is backed by the weight of his authority. In some cases it is necessary to repeat the treatment after a suitable interval. k ^ 42 Parasites of the Horse. In other cases a change, as from the turpentine to the second or third Hnes of treatment, is advisable. Another plan may be mentioned. It consists in using mechanical irritants for the purpose of clearing the bowel of parasites. The sub- stances used are iron filings, tin filings, finely powdered glass, cowhage, etc. This line of treatment is happily out of date. It is not a safe method for the horse, and also uncertain as to the parasite. It should not be used. In severe cases, a free use of tonics after the parasites have been expelled, is advis- able. Iron is the best of such tonics, but it may be combined with others thus : — ** Sulphate of iron, gentian and quassia, of each two drachms, treacle (molasses) and linseed meal to make a ball. One to be given night and morning." — (Finlay Dun). Or drachm doses of the iron may be given in powders along with the food, three times a day. In addition to the generous laxative diet spoken of, and the medicinal treatment, all Parasites of the Horse. 43 I animals should have free access to rock salt, which they may lick at will. SUB-SECTION II. Oxyuris airvula* or Pin Worm. — *'This worm, of frequent occurrence in the horse, is often considered of trifling importance clinically, but it has power to induce irrita- tion, indigestion, and lowering of the vital force, which ought not to be overlooked. Steady marasmus and impairment of health may, in many instances be directly traced to the presence of these worms. Form. — Very distinctly made up of two portions, body and tail. The body is smooth, the head cone-shaped, and the mouth armed with horny plates, or bars. The tail, which starts rather suddenly from a gradually attenuating body, is prolonged, in awl fashion, to a length equal to the body." — (Robertson). The worms meas- ure about one and three-quarter inches in length, that is, males — the longest of them ; the female may measure as much as four * These parasites are improperly spoken of by some veterin- arians as ascarides. 44 Parasites of the Horse. inches. The species is easily recognized by its long, awl-like tail. Habitat. — *'The large intestine, colon, caecum and rectum. In the latter in par- ticular they are often found, occasioning much irritation." Numbers. — Occasionally found in great numbers. Development. — "The ova, on extrusion from the parent worm, and from the bowel do not require an intermediary bearer in which to lodge previous to settling in the canal of the horse." It seems probable *' that they are conveyed to their host in a direct manner, by food or water. In the stomach, or small intestine, the embryos are set free. In this situation they seem to abide for two to four weeks, until they reach sexual maturity, when they proceed onwards to the large intestine, where they remain until discharged in the usual manner. " Symptoms. — With this parasite present in sufficient numbers to disturb the health of the animal, we have the general symp- toms of worms, a depraved appetite, de- Parasites of the Horse. 45 vouring of strange materials, as lime, sand, manure, etc., very often in enormous quan- tities. There is a dry, rough coat and scurfy skin, alternate constipation and diarrhoea, with general wasting, and inability to do ordinary work. In addition there is an irritable condition of the skin at the exter- nal openings, viz., at the nostrils and anus, the latter causing rubbing of the tail. There is also a yellow colored incrustation around the anus, which is formed partly of mucus and partly of the eggs of the worms. Diagnosis. — The unthriftiness of the animal would cause suspicion of worms, and the great tendency to rub the tail, showing irritation of the parts, would lead to examination of the anus. The presence of the yellow incrustation spoken of above is presumptive evidence of the irritant being oxyurides ; the diagnosis being con- firmed if necessary by examination of the faeces, either with or without a purgative. Prognosis. — Generally treatment is suc- cessful, therefore the owner may be assured f n I i I 46 Parasites of the Horse. of the recovery of the animal, so far as these parasites are concerned. Treatment. — Preventive. —''No horse properly looked after can be infested with these worms. Local washings and stable cleanliness being secured by an attentive groom, the animals are safe. Prophylactic measures of this kind are ail powerful against infection," (Cobbold). But it is also neces- sary to see that the fodder and water are clean, and uncontaminated by ova. The method of infection spoken of by Professor Robertson, viz. : one horse receiving the ova by licking them off from around the anus of another may be almost completely prevented by attention to the local means spoken of above. T RE ATM ENT. — Medicinal. — In speaki ng of treatment it will only be necessary to refer to what is said under Ascaris megalo- cepkala {-^Agit 39). Either of these agents may be employed with success, following the directions there given."* In conjunction with these remedies, how- *Dr. Cobbold says santonin is not successful for oxyurides. I / ; Parasites of the Horse. 47 ever, enemata of solution of common salt, tobacco, or turpentine may be given with the greatest benefit. If the turpentine be used, two to three ounces may be dissolved in a pint of raw linseed oil. An infusion of tobacco may be made for the same purpose (one drachm to one pint of hot water), or the old-fashioned tobacco- smoke clyster may be used. The latter "is most conveniently given by filling a common barrel syringe with smoke drawn from a tobacco pipe. Three or four syring^e- fuls are sufficient at a time." Whichever enema is preferred, its use is to be persever- ed in for some weeks, two or three times v/eekly; so as to destroy those parasites which gradually pass back to the rectum. In all severe cases also, the use of sulphate of iron, as a tonic, is advisable. In many cases it is useful to change the diet ; giving soft, laxative food. Salt should be given freely in mashes, also placed within the reach of the animal. 48 Parasites of the Horse. n ■ I I SUB-SECTION III. Filaria oculi, OX F. papulosa. (Rudolphi). Form. — It is a round worm. " The head is broad, the mouth opens widely, surround- ed by a ring of chitine, with two prominent denticles, one on either side, also two papil- lae (Fig. 7). Males attain a length of three inches, females of seven. The tail of the male is spirally twisted, that of the female only slightly curved." (Cobbold). The caudal extremity shows sixteen papillae, eight on either side. Habitat. — This has usually been thought to be the eye — the anterior chamber. Cer- tainly it is occasionally found in that situa- tion, moving freely about in the aqueous humor, but from the specimens sent in from all parts of the country I am convinced it is much more commonly found in other parts of the body. Cobbold speaks of it as having been found in the thorax, abdomen, mem- branes of the brain, muscles and cellular tissues. It is not uncommonly found in the peritoneal cavity, as shown by speci- mens found in the dissecting room of the Parasites of the Horse. 49 Ontario Veterinary College. In fact these Filaria papulosa appear to be the most common parasite to be found in this posi- tion. But, although not unfrequent out- side of the intestines they are never found in the lumen of the bowel. On the other hand, Ascaris megaloceptala and Oxyuris ctirvula, inhabitants of the intestines, are never seen outside of it. Speaking again of F. papulosa, Dr. Manson, an authority on entozoa, considers that the eyeball is not really the proper habitat for this parasite, but it reaches there as an accidental result of its wanderings. It is a fact that they are often found in nests, several being together. The same authority explains this curious circumstance by stating that, when one comes across the track of another in his wanderings, sexual instinct impels it to follow up the track. These tracks are of a yellow color, and sometimes may be readily seen by the naked eye. Numbers. — If in the eye, usually single, although not necessarily so. One operator 5° Parasites of the Horse. removed three of the worms from an eye. In other parts of the body, not numerous. Development. — Not yet fully under- stood. Symptoms. — (a) Eye. — The worm at first sets up no irritation, no symptoms therefore appear, but it may chance to be seen moving freely in the aqueous humor. Soon, however, " the symptoms seem to be conjunctivitis, the cornea obscured by nebulous effusion, the eyelids closed, and intolerance to light."'"' (b) In other parts. — As the parasite has been found in many parts of the body, it is possible that it sets up irritation in any of these localities, thus causing the most diverse symptoms. So far, however, there is no record of it having been found in sufficient numbers to produce noticeable symptoms. A case was reported from Owen Sound in which these worms were supposed to have caused the death of the colt. He had been unthrifty for some time, nervous *Percival. Parasites of the Horse. 5« and irritable, coat staring, appetite irregu- lar, a discharge from the nostrils, a stag- gering gait, showing nervous twitchings of the muscles of the head and neck. At last he went down and died. Post mortem ex- amination revealed a few Filaria papulosa outside of the intestines, not sufficient to have been the cause of death. A diagnosis of irregular strangles had been made before death, which, no doubt, was correct. Diagnosis. — This can only be made positively by seeing the worm in the eye. If it (the parasite) be wandering in other parts of the body, the diagnosis is only a matter of conjecture. Prognosis. — If in the eye, it can with certainty be removed, but nothing can be done to dislodge the parasite in other parts of the body. Treatment. — Preventive. — The life his- tory not being fully known, only general directions as to cleanliness, good food, the avoidance of stagnant water, can be given. Also all animals should be kept up in the best condition of health. 52 Parasites of the Horse. Treatment. — (a) In the Eye. — The ani- mal having been put under an anaesthetic and secured, a sharp-pointed scalpel is pushed flatwise through the cornea at its upper and inner m rgin. The aqueous hun.or escapes, and with it the worm, or this can be drawn out with a fine pair of forceps. The wound gener?.lly heals by first intention, and the aqueous humor is gradually re-secreted, filling the anterior chamber of the eyeball. Generally no bad effects result, although there may be a slight cicatrix at the point of puncture. The puncture having been made, however, in the position spoken o{, the cicatrix (if any) does not interfere with vision. In reference tu treatment T. Marriott, A.V.D., India, writes '*■ During cavalry exercise on the 12th of January * * # a Filaria oculi was noticed springing gaily about in the aqueous humor of the near eye of a mare. " I delayed operating in order to procure some cocaine. On the following ^.^y # # # J punctured the cornea, •Veterinary Journal, 1890. 1^ '■ ■ I Parasites of the Horse. 53 * * * but no Filaria escaped. On careful examination through the now fairly opaque cornea, I detected the parasite near the inner and lower margin of the cornea, having attached itself to the iris. I then punctured immediately over the parasite. It escaped this time, but the amount of iritis set up by the Filaria having attached itself to the iris, considerably retarded re- covery. " To my surprise, this mare was admitted to hospital again on April 14th, with an- other Filaria in the near eye. * * * The cornea was punctured at once. * * * no iritis or ill effects followed ; the cornea 'cleared in a short time, and the horse was discharged. I record this case * * * (partly) to show the folly of postponing the opera- tion. Although a four per cent, solution of cocaine makes the operation painless, I shall never wait for that in future, for the parasite does not long continue to spring about as gaily as it does at first, but soon attaches itself to the iris ; the tail then is the only portion moving, but this soon 54 Parasites of the Horse. winds itself around the body, descriljing a loop like the top of a driving whip, with the lash wound around the stock. When the worm assumes this form, punc- turing the cornea is useless, at least it has been so in my practice." There is no treatment for the parasites when they are wandering through other regions of the body. SUB-SECTION IV. Strongylus armatus (Sclerostomum equin- uin — Leuckart), or Palisade Worm.* This is considered by Cobbold to be the most important of the round worms of the horse. From its peculiar wandering habits, it is the cause of various and serious disturbances. 1 wo varieties have been de- scribed, the smaller and the larger (minor and major) but these are simply the dif- ferent stages of growth of the parasite. Form. — A round worm, measuring from one to one and a half inches in length (male) the females being about two inches. *Named the Palisade Worm because it is so frequently found infesting the coats (or walls) of the blood vessels. \ Parasites of the Horse. 55 In both sexes the head is armed witl\ numerous, closely set, upright denticles, surrounding the opening like the teeth of a trephine. It is indeed an armed strongle. The tail of the male presents a well de- fined enlargement (bursa) while that of the female tapers, but is somewhat obtuse. Habitat. — The mature form (Strongy- lus ar^natus major) may be found in any part of the intestinal canal, but more commonly in the colon. The immature form (St. armatus minor) length, one inch and less, selects the coats of the arteries (especially the anterior mesenteric) in which to burrow. The parasite may also be found in almost any part of the body, as its wanderings from the vessels to the intestines carry it in everv direction. Professor Williams states that sometimes it pierces the eyeball. Numbers. — Generally few, but occasion- ally they are present in enormous numbers. Development. — The formation of em- bryos in the egg dots not take place until the eggs have been dropped from the host. These embryos, having escaped from the 56 Parasites of the Horse. 'i .^ggy Speedily develop. The resulting larvae have considerable power of motion, and bury themselves in the moist earth. Here, they remain for two or three weeks, and emerge considerably shorter than before, from the loss of their long tails, (Robertson). Leuck- art states that they then pass into the body of an intermediary bearer, such as a water snail. Having encysted themselves there, such bearer may be swallowed by the horse in food or water. In the stomach of the host the soft 'body of the snail is quickly dissolved by the gastric juice, and the embryos are set free. From the stom- ach and intestines they pass to the blood vessels ; and among all the vessels they seem to prefer the anterior mesenteric. The myriad little worms lodge in its walls, each one inflicting a small wound in doing so. These wounds cause an inflammation of the coats of the vessel (endo-arteritis) and a consequent thickening of the coats ; producing what is known as an aneurism. During this thickening of the coats, the parasite grows and becomes about one inch Parasites of the Hors^. 57 in length. It is immature while here, but the mouth is gradually developing its arma^ ture, and sexual organs appear. The skin is then cast, and the parasite endeavors tp find its way back to the intestines. In doing so it may bore (by means of the strong armature around the mouth) through almost every tissue of the body. Reaching the intestines, sexual organs are perfected, and it becomes fully mature. Young animals are much more liable tp succumb to the attacks of this parasite thar\ are the aged, although the proportion of animals affected with aneurism is greater in the older ones. Symptoms. — In view of what has beeq said, it can be seen that the symptoms^ may be divided broadly into — (a) — Those resulting from their presence in the intestines or other parts of the body, excepting the walls of the vessels, and (d) — Those resulting from their presence in the w^lls of the vessels. (a) — If in the intestines in considerably numbers there may be general unthriftin^^s^ 58 Parasites of the Horse. i together with indications of intestinal irri- tation, shown by diarrhoea alternating with constipation. If wandering in other parts of the body the marasmus may be so ex- treme as to eventuate fatally without other very noticeable symptoms. ( Vide Miller's case, page 63). In addition, however, to the extreme weakness spoken of, so much irritation may be set up as to cause exces sive nervous action, simulating convulsions ; or, on the other hand, paralysis, generally temporary, may be the result.* {b) — Their presence in the vessels is productive of the most serious consequences. We are already aware that aneurisms, some large, some small, are a result of their presence. Only one aneurism may exist, or several, and on different vessels. They vary in size from a pea to a man's head. The pathology of these aneurisms has been worked out by Bollinger. His more important points may be thus summarized : I St. The attacks of the Strongyli on the inner coat of the artery, causing endo *See page 70. ,L_ Parasites of the Horse. 59 arteritis, results, in the first place, in the thickening of the whole of the coats, con- sequently enlargements upon portions of the vessel ; and secondly, in the formation of a clot (oi more than one), partially block- ing up the vessel. The thickening of the walls and the presence of the clot (throm- bus) narrows the lumen of the vessel, con sequently tends to increase the aneurism 2nd. The clot may occlude the artery, but most generally only narrows its calibre. It may spread towards the smaller vessels, or towards the aorta. The thickening of the coats of the vessel, and the formation of a clot, are, then, the two results of the presence of St. armatus. Now, what symptoms may we expect from these aneurisms."* In man, the chief symptoms of an aneurism are due to pressure upon the surrounding organs. But in the horse, aneurisms increase so slowly in size that pressure symptoms are seldom or never recognizable. Again, the accident of rup- ture, so common in man, is very rare in the horse. This is due to the enormous thick- 6o Parasites of the Horse. 1 ehing of the walls of the vessel in that animal. Out of the innumerable cases of aneurism in the horse, but eighteen cases of rupture are on record. Bollinger, who has given much attention to the matter, is of the following opinion : Large numbers of cases of colic, of gas in the intestines, etc., are the result of the thrombi. The cases are caused in the following manner : A portion of the clot breaks off, is carried by the blood stream to a small vessel, which it fills, thus cutting off the blood supply to the part. This causes partial or complete paralysis of the bowel. Peristaltic action ceases, the faeces arc not carried forward, and colics result. Not only do colics result in the manner stated, but the palsy of the bowel tends much towards the production of ekiormous quantities cf gas in the intestines, of rup- tures of the intestines, &c. It becomes a serious question, are those colics ofcen caused in the manner spoken of, or, in other words, is verminous aneurr Parasites of the Horse. 6i ism frequently the cause of those dangerous conditions. In endeavoring to answer this question, the number of horses thus affected must be taken into account. Professor Bruchmuller estimated the percentage of horses (in Europe) affected with aneurism at about ninety per cent. BolHnger says about ninety-four per cent. These figures have reference to horses over six years old, and the older the horse, the more liable he is to this form of aneurism. Talking these figures, Bollinger says, ** Among every forty horses affected with internal disease, forty are ill with colic. Among any hundred deceased horses, forty have perished from colic, and among one hundred colic patients, eighty-seven re- cover and thirteen die." These figures prove what a frequent affection this is, and how many victims it claims. Bollinger holds that blocking of the mesenteric arteries as spoken of above, is the cause of the vast majority of colics, " the causes hitherto ac- cepted being for the most part insufficient." 62 Parasites of the Horse. ** Considering the great losses * * * that are occasioned by the colic of horses to the horse breeder, to agriculture and to the general welfare, it is of the highest im- portance to discover means which should prevent the introduction to the animal of the embryos,' * which are generally taken in with his food. \ . Granting that these careful observers are correct in stating that ninety horses out of every hundred are the subjects of ver- minous aneurism in Europe, the question arises, what proportion of horses are so affected on this continent ? That is a ques- tion which can only be determined by a great number of independent observations carried on in different parts of the conti- nent. It may be tentatively given as about one-third that of Europe. If these data are correct, it follows that colics from the cause of which we are speak- ing cannot be more than one-third in num- ber of those seen in Europe. But, while *The foregoing remarks on aneurisms are mostly condensed from Bollinger. Vide Cobbold's Parasites, pp. 368 to 373. Parasites of the Horse. 63 s admitting the likelihood that so skilled a clinician as was Bollinger is correct in his opinion so far as his observations go, it has yet to be proved that verminous aneurisms are in any case a cause of colic in this country. Close observations, extending over a considerable period, are necessary to settle this important point. In view of what hr.s just been stated, it nvuot be admitted that there are no positive symptoms of the presence of Strongylus armattis in the walls of the vessels. It may yet be proved, however, that they produce colics and intestinal derangements in the manner spoken of. Apparently causeless colics, especially occurring in an unthrifty animal, should be looked on with suspicion. Lameness in one or other of the limbs (produced in the manner spoken of under the head of Diag- noses) may also be a symptom. The following interesting case was sent by j. H. Miller, V.S., Seville, Ohio :— 'M was recently called to see a colt, two years old, which was very much run down. He •4 Parasites of the Horse. Was so weak as to be unable to get up alone ; Aild had been failing for about two months before I was called in. After examining the animal, I informed the owner that treatment was useless. The death of the colt tbok place two days after my visit. I was notified, and visited the farm in order to make a post 7fi07'tcni examination. I found parasites in vast numbers in the abdominal muscles, most numerous, however, in the flanks. I examined the whole of the alimentary canal, but found no worms of any kind. A few bots were in the stomach. No other cause of death could be dis- covered than the parasites in the muscles. # ^^ # The colt was of the draft stock, and was raised on bottom lands, where he Would have access to stagnant water. He Was noticed to be out of health in the middle of the winter, but was turned out to grass in the spring with five other colts, these being apparently healthy. I did not look for parasites in the blood vessels, but cut into several of the large vessels and did not observe any." Parasites or the Horse. 65 \ : Another case was reported from the same locality. This colt also was on a bottom farm and began to lose flesh two or three months before death. In this case a pos/ mortem showed the parasites in the abdominal muscles very plentifully, and no other cause of death was discovered. DiAdNosis. — Apart from the known fre- tiuency of abdominal aneurism, caused by St. armatiis, which amounts, as has been said, to probably thirty per cent, in a^:jd animals ; general considerations would be the principal means of arriving at any conclusion. If an animal presents that general unthriftiness which is so marked in many cases of parasitism, and especially if he be liable to frequent attacks of colic without apparent cause, we may suspect the presence of this parasite. And a his- tory pointing to embolism of an artery (perhaps most frequently seen in one of the iliacs) would tend to strengthen our suspi- cions. For there can be little doubt but that this condition, formerly ascribed to inflammation of the artery is generally 66 Parasitfs of the Horse. ! l\ produced by a bit of fibrin blocking up the vessel. And such bit of fibrin, in the great majority of instances, comes from one of the thrombi spoken of, which exist in connection with these aneurisms. If the bowel be now thoroughly cleared by cathartics, and the examination of the faeces shows no worms, or ova, their absence would exclude the idea of Ascarides or Oxyurides, but would not necessarily invali- date a diagnosis of Strongyli. The pres- ence, however, of even a few of the latter parao'tes would tend to confirm it. Prognost^. — A favorable opinion may be given so far as those in the intestines are concerned. They may generally be got rid of And even in regard to those in the vessels, it may be stated that they will ultimately pass into the intestine, whence they can be removed. It must be remembered, however, that in their wan- derings to reach the intestine they may produce such injury as to cause death, as in the cases quoted. As to the results of their residence in the walls of the vessels, Parasites of the Horse. 6, up the :h( viz., the aneurisms, the prognosis must be unfavorable ; these effects no treatment will remove. Treatment. — Preventive. — Thorough stable cleanliness, care in the selection of fodder, avoiding such as comes from low- lying, swampy places, with the use of pure water (such as that from deep wells), will almost certainly prevent the ingress of this dangerous parasite. So far as pasturage is concerned, low- lying lands must be avoided. Water from clear running streams, or wells, is not likely to contain the ova. Infected fields may be renovated by drainage and good thorough cultivation. Treatment. — Medicinal. — Lit tie need be added to what has already been said in regard to this (pages 39, 40). Oil of turpen- tine, or santonin, as there spoken of, may be used with success in so far as those in the intestines are concerned. Treatment for those in the vessels or tissues is useless. The animals must be kept in a state of vigorous health. sn Parasites of the Horse. SUB-SECTION V. Strongylusietracanthus,* or Four-Spined Strongle.— This entozoon was formerly mis- taken for an immature form of the worm spoken of in the last section, viz., Strongy- lus arniatus. It is, however, essentially different. It is not so common as St. armatus. Form. — A very small round worm, the male measuring j^ to j4 inch in length, the largest females as much as ^ of an inch. A number of denticles surround the aperature of the mouth, but they are not so easily seen as are the four large spines which are upon the outer protuberances. It also possesses two neck bristles. The body is smooth externally, and is of a well- defined red color, as it is a true blood sucker. The sexes are of nearly equal size, and are often seen united <^ogether. The tail of the male is furnished with a three-lobed hood ; that of the female is pointed. Hahitat. — In the immature state they I t "Formerly known by the name Trichomma antiata. Parasites of the Horse. lie coiled up in the walls of the caecum and colon, where they sometimes produce ex- tensive changes, causing ''ecchymoses, con- gestion, inflammation, and many small abscesses," the walls often being much thickened. When mature, they are found in the lumen of the bowel.* Numbers. — Only occasionally numerous. Development. — The ova from the ma- ture worms are expelled with the faeces, while the larvae, which subsequently escape from the ova, are believed to enter some intermediary bearer. These bearers, on fod- der or in water, are swallowed by the host, the larvae set free in the stomach, and^ reaching the caecum and colon, bore their way into the walls of the tube. On look- ing at the mucous membrane, opaque spots are plainly seen of an oval shape, about one-tenth of an inch in diameter. These are capsules containing an immature worm coiled up. Here they remain for a time undergoing certain changes, and then pass back into the bowel, becoming fully mature. •Professor Robertson. '^ 70 Parasites of the Horse. Symptoms. — In some cases symptoms are not observed until within a few hours of death. But generally speaking there is general unthriftiness and marked wasting, often with symptoms of severe intestinal irritation. The pain is frequently of an inflammatory type. The parasites may so wound the smaller vessels of the intestine as to cause fatal internal hemorrhage. Reflux disturbances are occasionally seen as shown by convulsive spasms, paralysis, etc.*' G. Taylor, V.S., of Upper Alton, Illinois, *While it is not difficult to understand that the parasites, by irritating the nerves of the intestines (or other parts), may so stimulate the central portions of the cerebro-spinal sys- tem as lo cause spasms, simulating true convulsions, it is more difficult to see how these same parasites can be the cause of paralyses. One theory is as follows : " That an irri- tation, operating upon certain sensory nerves, produces im- pressions which, after impinging upon the properly related grey matter in the spinal cord, are thence in part reflected along vaso-motor nerves regulating the calibre of^ certain blood vessels which supply either (a) the portion of the spinal cord in relation with the paralyzed parts, or else (l>i the great nerves or the muscles themselves of the paralyzed parts. In either case, this reflection of impressions resulting from irri- tation of sensory nerves, upon such special groups of vaso- motor nerves is supposed to lead to a persistent spasm of the vessels, which they innervate, so as to cause a continuous anaemic condition, either of certain vascular territories in the spinal cord itself, or else of the related nerve trunks and muscles." (Brown-Sequard. Vide Quain's Dictionary, page 1496). The anaemia spoken of may be complete and result in permanent paralysis ; or it may disappear rapidly, if the irritant be removed. massm Parasites of the Horse. 71 nal writes of four cases substantially as fol- lows : — " The horse from which the para- sites I send you were taken is the fourth I have met with in my practice, all having the same species of worm. These which I send were taken from about six inches of the mucous membrane of the colon. I am at a loss to know what name to give them. I showed them to Dr. of this city, in his opinion they are a variety of Trichina. In each of the cases which I have seen, the symptoms occurred suddenly, and with great violence, the disease terminating fatally in a short time. The first case was in Mani- toba in 1882. I did not see the horse till after death. Post mortem examination re- vealed millions of nematoid worms covering the mucous membrane of the caecum and colon, also covering the contents of these bowels. The small intestines contained a few of these parasites, with a considerable amount of blood. There was no appear- ance of inflammation of the bowels nor any discernable cause of death, except the para- sites spoken of. 7? Parasites of the Horse. "The second case was in the State of Iowa. The mare was apparently in good health that morning. About eleven a. m. she showed signs of weakness. I was sent for, and when I arrived about one o'clock, p.m., I found her down, the pulse running one hundred beats per minute, almost im- perceptible at the jaw. The animal was gasping for breath, and showed a remark- able paleness of the mucous membrane. Death occurred about twenty minutes after my arrival. The post mortem examination revealed a condition similar to that in the first case described, considerable blood be- ing found in the small intestines. *' The third and fourth cases were seen in this State (Illinois). A horse, five years old, was taken suddenly ill. When I saw him the same morning, the pulse was one hundred and ten, respiration seventy per minute. There was extreme weakness, but no perceptible paleness of the mucous menir brane, Sensation was gone, sweats ber dewed the body, the nose rested on the ground and dropped again if raisecj, Parasites of the Horse. 73 While looking at him, the owner came to say that a mule of his had suddenly shown the same symptoms as the horse. They both died in two hours from that time. Post mortem appearances in the mule were the same as in Nos. i and 2, excepting that there was no hemorrhage. The mucous membrane was so riddled by perforations that it could easily be scraped off. The examination of the horse showed a similar condition of the caecum and colon." S. H. Slocock, M.R.C.V.S., of Houn- low, writes as follows '* " Some months ago I was called to see two colts (two years old). They were said to be doing badly and scouring. I found both at grass ; one was purging violently ; was greatly ema- ciated, and showed every symptom of ex- haustion from parasitic disease, the other was showing the same symptoms in a less degree. On examining the fseces, I found the blood-red strongle present in great numbers. * * * I had the colts removed to warm quarters, and they were allowed a * Veterinary Journal, 1886 I 74 Parasites of the Horse, ; I most liberal diet ; a supply of rock salt and |, reparations of iron." The weaker colt died in a few days, as Mr. Slocock had ex- pected, but the other gradually recovered, although for weeks he passed parasites at every motion. He continues : " I was called to a colt on another farm. He was one of five, and had been housed at night all the winter and WLil cared for. He showed the same symp- toms as the above colts, but for a fortnight I failed to find the parasites in the faeces. Suspecting the true origin of the purgation, I commenced the tonic treatment. The colt became gradually weaker until, seeing that the case was hopeless, I advised his destruction. " Post mortem examination revealed the caecum and the whole of the colon in a marked state of congestion and the para- sites (St. tetracanthus) in great numbers in the canal. The larval forms could be dis- tinctly seen arranged in a circular form under the mucous membrane of the intes- tines, also there were numerous punctures Parasites of the Horse. 75 of the membrane, showing the points at which the forms had made their exit on reaching maturity. .^ :rr ^ylus amiatus was present with the . in ome numbers." Occasionally thes^ Tv^^^gyli (St. tetracan- tJms) cause many deaths in farm districts, as occurred in Wales r,j years ago. Rees Loyd, V.S., states that in one district alone, upwards of one hundred mountain ponies perished from this cause. He says that the ponies thus affected are noticed to be ailing " for three or four weeks, becoming rapidly emaciated and dying from exhaustion." Mr. Loyd thus describes one case : — "The case had suffered from colicky pains for about two months * * * \ y^^^ gent for one evening about an hour before the animal's death. * * * j remained with it the whole of the time, of which about forty-five minutes of the most acute pain was borne by the trembling beast, which was leaping, rolling and tossing about. * * * Suddenly all was still, he quietly rose to his feet, and nipped grass as if nought had troubled him. I then trotted — - 'xiTA 76 Parasites of the Horse. him quietly to a corner of the field, where he got down to rise no more. The next day I examined him, and found thousands of four spined strongles." Diagnosis. — The general unthriftiness due to parasitism is more marked in con- nection with the presence of these parasites than with some others. Rapid wasting, with intermittent attacks of pain — which more resembles inflammation than colic — would lead to a suspicion of their presence. Persistent diarrhoea may be present; (i)ages 73, 74). These parasites have also a consid- erable tendency to produce nervous symp- toms. Paleness of the mucous membrane would suggest internal hemorrhage, due to wounds inflicted by their armed mouths. But a positive diagnosis can only be made by finding the worms, or their ova, in the intestinal contents. Prognosis. — This depends upon the ex- tent of the infection. If the animal does not succumb to the more direct attacks of the parasite, a cure may be expected, that is, if re-infection be guarded against. Parasites of the Horse. 77 Treatment. — Preventive.— Th^ remarks made in connection with other entozoa apply here, viz., thorough cleanliness, the administration of food and water which can not convey the embryos in any form. The pastures must be such as are not likely to be infected, or, if infected, they must be cleansed by fire, salt, or ploughing and good cultivation, before being used for any horse. Treatment. — Medicinal, — Dr. Cobbold says : — '* The fatality of the disorder de- pends not upon the mature worms, but upon the wandering and sexually immature forms. All attempts to poison the entozoa, when once they have gained access to the tissues * * * are worse than useless. By all means let the animals have a dose of aloes in the first instance, followed by warm bran mashes, but thereafter let every care be taken to support the patient's strength. Especially should the adminis- tration of the oil of turpentine be avoid'^d."''*' * Cobbold here evidently has reference to large doses. See the following paragraph. 78 Parasites of the Horse. In Professor Williams' work there is given an account of Iceland ponies infected with this parasite. One died, the others were then treated with oil of turpentine in small doses (two drachms) night and morn- ing, beaten up with eggs and milk, and all recovered. The strength of the animal must be kept up to the highest point by liberal and suit- able diet — nourishing, easily digested, and rather laxative — and the administration of suitable medicine, preferably iron and bitter tonics. SUB-SECTION VI. Spiroptera megastoma, or large mouthed maw worm. — This small parasite is not by any means so uncommon as it was thought to be formerly. But several points in its life history have yet to be worked out. Form. — It is a minute round worm, the male measuring one-third, the female one- half of an inch in length. " The mouth is round, very capacious, and provided with four lobes, two of * which project over the Parasites of the Horse. 79 edge of the mouth, and each has two papillae." Habitat. — •' They are found between the mucous and muscular walls of the stomach. Their presence causes the ap- pearance of tumors, measuring from an inch to one inch and a half in diameter. These tumors are divided into spaces by trabeculce ' beams, ' which give them a reticulated appearance. One or more of the parasites are usually found in a tumor, although in some there are none, the para- sites " having passed from the tumor. (Robertson). Occasionally the contents of the tumors are found degenerated into pus, forming abscesses. Numbers. — Not usually numerous. Development. — Not yet fully known. Symptoms. — The animal carrying these guests is not usually sufficiently disturbed by them to show any symptoiris. Sp. megadoma is only recognized by find'dg the tumors in the stomach after death. In the present state of our knowledge, diagnosis and treat- ment are impossible. 8o Parasitis of the Hor^e. Spiroptera microstoma, or small mouthe* < maw worm, is found free in the stomach. It is not known to produce symptoms. It is probably the same parasite as the one just mentioned, in a different stage of develop- ment, although some hold it to be a distinct species. It is larger than Sp. megastoma. Section V. TREMATODES OR FLUKE WORMS. This order is mentioned only to com- plete the classification. One species, Fasciola hepatica^ may occasionally, but very rarely, be met with. This parasite produces the disease known as " Rot " in sheep, but has not been found in sufficient numbers in the horse to produce disease. In size, it varies somewhat, but is seldom larger than one inch in length by half an inch in breadth. It is a flat worm, re- sembling in outline a small leaf, and may be found in the gall duct, occasionally in the substance of the liver. *In some works this is spoken of as Distoma hepaticum. Cobbold considers F. hepatka to be the more correct name. Parasites of the Horse. 8i The foregoing are the more important of the entozoa of the horse. Ascaris megalo- cephala and Oxyuris curvula are very com- mon, every veterinarian and almost every owner of a horse has seen and knows these worms. After these, Filaria papulosa and Strongyhis armaius are the commonest, al- though they are rarely seen by the practi- tioner. Strongylus tetracanthus is still more rarely seen, while Spiroptera megastoma and 5". ''Hicrostoma are very occasionally discovered in the stomach at a post mortem examination. But although these are all that are likely to be met with in practice, it will be well to give an even more com- plete list, which, by indicating the locality in which the entozoa are found, may prove to be an aid in identification of some of the rarer parasites. "* . *As an example of how represer tatives of several different species may infest a single host, Vtn Beneden (Animal Para- sites, p. 91) notes that Krause found in a two year old horse, over 500 Ascaris megalocephala, 100 OxytiHs curvula, .187 Filaria papulosa, 69 Tivnia perfoliata, 21^ Slrougylus armatuSt and several millions of Stroii^lus tetracanthus. Vide Leuck- art, p. II. 82 Parasites of the Horse. LIST OF ENTOZOA OF THE HORSE. NAME. USUAL LOCATION. I. Ttcttia ptrfoUata Large intestines. IL Ascaris megalocephala Small intestines. in. Oxyuris curvula Large intestines. IV. Filaria oculi, or F, papulosa . . Aqueous humor of eye-ball ; also in peritoneal cavity and other parts of body. V. Strongylus artitatus, known also as Sclerostomum equi- num or amiatum (mature) Intestines. " " (immature) In the walls of the blood ves- sels, especially the anterior mesenteric; also in other parts of the body. VI. SirongylMS idracanlhm'' {yasXvix€). Intestines. " " (immature). Intestinal walls. VII. Spiroptera megastoma .... In small tumors in the stomach. WW. Spiroptera mhrostoma . Frae in the stomach. IX. Fasciola hepatica, known also as Distoma hepaticum Gd\\ ducts — Flat or Fluke Worms. X. Amphistoma ccllinsii Colon — Flat or Fluke Worms. XI. Echinococcus veterinomni . . Cysts in liver. XII. Canttnis cerebralis Brain (cystic form). •This was formerly known as Trichonema anitata. Parasites of the Horse. 83 NAME. USUAL LOCATION. XIII. Filaria lachrymalis Between lids and eye-ball, and in the lachrymal ducts. XIV. Otuhocerca reticulata .... Coiled in the muscles. XV. Strongylus micrurus Bronchial tubes. XVI. Strongylus or Eustrongy- his gigas Kidneys. XVII. Filaria sanguinis equi (microscopic) .... Floats in the blood.* *Bots, treated of in Section vi., do not properly belong to the entozoa. 84 Parasites of the Horse. Section VI. 4 BOTS. Bots are the larvae of certain insects, known commonly as gad-flies. The com- mon gad-fly (CEstrus equi or Gasirophilus equi) lays its eggs on many parts of the horse, principally on those j)arts which can be reached by the mouth of the animal. There are other varieties of gad-fly, how- ever, one of which places the egg in the intermaxillary space, another attacks the nose, etc. Form. — As seen in the stomach, the bot (being the young of Gistriis equi) is of a light reddish color, about half an inch in length, tapering to both extremities. At the smaller extremity is the head, upon which may be seen the oi)ening of the mouth. At each side of this opening there is a strong hook by which the parasite can hold to the mucous membrane. The skin is not smooth, but shows a number of transverse elevations and depressions, which give it a ringed appearance. n Parasites of the Hokse. 85 1 f Numbers. — Generally few, but some- times present in enormous numbers. Devklopment. — The gad-fly attacks the horse late in summer, and deposits its eggs on some part of the animal which can be reach by its mouth, viz., on shoulder, knee, etc. The eggs having been firmly glued to the hairs, warmth and moisture are necessary for their development. These are supplied when the animal licks the part; then the growth of the embryo begins. In about three weeks they have assumed the maggot like form, and are transferred to the mouth, probably by the tongue or teeth of the animal, while li' iig or gnawing ;.he part. A great man\ irvai perish duiirig this passive mode t' migration, some being droi)ped fro the mouth, others being crushed in t ^e fodder during masti- cation. But some ;ire carried down from the mouth to the stomach, either with food or water. Occasionally in their passage downwards, they lay hold of the mucous membrane of the piarynx, and remain in that situation. The majority reach the 86 Parasites of the Horse. stomach however, and by means of the two large hooks upon the head, anchor them- selves so firmly there as almost to defy dislodgment. They may be found thus anchored on any portion, either of the cuticular or villous mucous membrane of the stomach, or even in the small intestines leading away from that viscus. Wherever they lay hold, they retain it until the following spring, gradually growing the meanwhile.* Having attained their full growth by gradual development through the autumn, winter, and following spring, they, during early summer, voluntarily loosen their hooks from the mucous membrane, fall off among the contents of the stomach, and are carried with the faeces, away from the ani- mal. Having been dropped upon the ground, they bury themselves in the soft soil, re- maining there for a period of six or seven weeks. They are gradually developing from the pupa state to that of the insect, • Vide Cobbold on Parasites, p. 385. Parasites of the Horse. •7 and, at the end of that time, emerge as perfect gad-flies. The history may be summarized as fol- lows : The eggs are laid in the autumn. The same autumn the maggots escape from the Ggg, are carried to the stomach, and gradu- ally grow there cj rMg the following eight months. They then loosen their hold and pass out with the faeces, bury themselves, and after a period of six or seven weeks'"* emerge as gad-flies. This is the life history of 6^. e^/tii. There are several other species (as G. hemorrhoid- alis) which attack the horse, but it is un- necessary to speak particularly of them. Symptoms and Effects. — These are very indefinite. Bots undoubtedly may set up serious irritation, but *' the irritation caused by them is not easily distinguished from ordinary indigestion," nor from the condition produced by some of the entozoa. *Cobbold says six or seven weeks. Gamgee says eighteen or nineteen days. 88 Parasites of the Horse. " It (the indigestion) may be tympanitic or not, or accompanied or not with diarrhcta, and of the most variable intensity."* That they may mechanically interfere with digestion to a serious extent is ad- mitted. If collected in large numbers around the cardiac orifice, they may pre- vent the proper ingestion of food, or, if at the j)yloric opening, the food may not pass from the stomach properly. The symptoms and results of a peculiar case are reported by T. Tegg, M.R.C.V.S.+ " The animal showed dull, continuous i)aiii, was very weak, and would not cat. The second day, still weaker. The third day, debility was more marked, while it died on the fourth day. It died in great abdominal pain. The autopsy showed enormous dis- tension of the stomach, it being largely occupied with food. Ninety-seven bots were picked off the villous coat, near the l)ylorus, and the irritation which had been set up by their hooks in the mucous mem- * Viik Law's J^cterinary Adviser, \i 172. \ Veterinary Joiinial, i^^2. Parasites of thf, Horsk. 89 bnine resulted in considerable tuinefiiction ; so much, indeed, as to close the py^loric ori- fice, and thus prevent food from passing into the intestines." One case of tetanus is reported as having been due to bots, and it is possible that they may perforate the stomach, leading to symptoms of peritonitis, which may result in death. Bracy Clark held that bots actually aided digestion by stimulating the tlow of gastric juice, but this idea is not now en- tertained. If the bots adhere to the mu- cous membrane of the pharynx they pro- duce a soreness of the throat, with, usually, a discharge from the nostrils, I)ia(;n()S1s. — A positive diagnosis is almost impossible. The history of the case may throw some light upon it. If the ani- mal has been out at grass the previous sea- son, he is almost sure to possess some bots. A history of marked indigestion (especially if recurring) without other ade(|uate cause, the attacks coming on in the spring or early summer, the animal being weak and un- thrifty, the bots passing away in the dung yo rAkASITES OF THE HORSE. and the animal tiirninj^ up his 1 ip as if Tiau seated, these would all tend to show that the indigestion was due to the presence of bots. pROdNosis. If an opinion he called for in spring or early summer a favorable one may be given. Hut at any other time medicinal treatment is highly unsatisfactory. Tkkatmknt. Prcvtutiou. Preventive treatment is satisfactory. Horses exposed to attacks of giid-tlies may be protected to a large extent by oiling freely the portions of the body where the eggs are usually deposited. The eggs will not adhere to the hair when oiled. The long hairs should be trimmed off before oiling. The gad-rties belonging to one species always attack the intermaxillary space ; they can be warded off in many cases by a piece of cloth stretched between the two sides of the bridle. If the horse be valu- able enough, it is well to remove any ad- hering eggs every second day. T R K AT M K NT. — AIcdiciuaL — The v e r m i - fuges previously mentioned may be given, k i Parasites of the Horse. 91 t S but with doubtful success. T'lnlay Dun re- commends rubbini^ down two drachms each of aloes and assaHetida In hot water, adding when cool one ounce each of turpentine and ether. This may be repeated two or three times a week, leaving out the aloes if physicking takes place, but administering a cathartic dose if it does not. Large doses of carbolic acid, followed by purgatives, have also been well spoken of.* Professor Law thinks that vermifuges given as soon as the bot-tly season is over, and before the larvai have attained their thick skin, may be successful in removing them. The most successful treatment, however, is free [pur- gation at the time when they have relaxed their hold on the stomach. Their exit then may be hastened materially. If the parasite is in the pharynx, it may often be removed by hand. Those that attach themselves to the anus, causing con- siderable irritation and annoyance (shown by switching of the tail, etc.) may easily be picked off by forceps. *Dose for a horse, half a drachrn to one drachm (Law). IMAGE EVALUATION TEST TARGET (MT-3) // // ^ 1.0 I.I 11.25 |2j8 2.5 2.2 HIUu 1^ HE 1.4 mULb /i /. ^:^*" •> Photographic Sciences Corporation ^ \ SJ N> ^V 23 WEST MAIN STtf ET WEBSTER, N.Y. 14580 (716)872-4503 i\ 92 Parasites ok the Horse. GENERAL SYMPTOMS OF PARASITISM. While the effort has been made in this work towards a diagnosis of the separate species, it must not be forgotten that a host may harbor many species of entozoa at the same time (page 8 1 , note). The symptoms, in such a case, would be the general ones of parasitism — the special indications being more or less masked. Those general symp- toms are thus described : " There are gen- eral signs of ill-health, poor constitution, pot-belly, hide-bound, a scurfy, dry state of the skin, often with itching, irregular and often voracious appetite, foetid breath, diarrhoea alternating with costiveness, the passage of mucus with the dung, slight colicky pains with tympany, especially in the morning before feeding, a puffy swell- ing and itchiness of the anus, which is often surrounded with a fur of dried mucus, and above all the passage of the worms or their eggs." '^ I -«^; 1 ' *Law's Veten'fiary Adviser, p. 179. ! s Parasites of the Horse. 93 %' The figures here presented (Nos. i to 5) are diagrammatic, and intended to pre- sent the general outline of the parasite, but more especially to fix their relative sizes in the memory. They are life size, the smaller specimens having been selected for representation. •94 Parasites of the Horse. Fig. I. — AscARis Megalocephala. Length — Male, 6 to 8 inches. Female, 7 to i8 inches. Fig. II. — FiLARiA Oculi, or F. Papillosa. Length — Male, 3 inches. Female, 7 inches. (The figure is from a specimen found in the peritoneal cavity. Those located in the eyeball are, as \ rule, smaller). Fig. 1 1 1. — OxYURis Curvula, (altered from Law). ' Length — Male, i^ inches. Female, 4 inches. Fig. IV. — Strongylus Armatus. Length — Male, i j4 inches. Female, 2 inches. Fig. V. — Strongylus Tetracanthus. Length — Male, % to yi inch. Female, ^ inch. If (i I ^■' 4 I Parasites, of the Horse. 95 These figures (Nos. 6 to lo) are also diagrammatic. They are more or less magnified, but are not drawn to give any idea of the size, nor of the relation of one to another in this particular. They are outlines of the heads as they appear under slight pressure, and may be an aid to identi- fication in doubtful cases. :' 96 Parasites ok the Horse, Fig. VI. — Head of Ascaris Meoalo- CEPIIALA. Fig. VII. — Head of Filaria Oculi or F. Papillosa. Fig. VIII. — Head of Oxvuris Curvula (after Busk and Cobbold). F'iG. IX. — Head of Strongylus Armatus. Fig X. — Head of Strongylus Tetracan- THUS. % A Fig. 6. Fig 8 f;Q S ^'8^'« ^ .5'-