CALIFORNIA AGRICULTURAL EXTENSION SERVICE CIRCULAR 130 July, 1945 SHEEP DISEASES H. S.CAMERON // Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA CONTENTS PAGE Introduction 3 Disease in general 3 Causes of disease 3 Diagnosis 4 Treatment and prevention 5 Specific infectious diseases 7 Anthrax 7 Caseous lymphadenitis (pseudotuberculosis) 8 Infectious pustular dermatitis (doby mouth, pox) 11 Foot-and-mouth disease • 12 Eabies • 12 Tetanus (lockjaw) 12 Diseases of the digestive system 13 Lamb dysentery 14 Overeating (pulpy kidney, enterotoxemia) 14 Indigestion 15 Bloat 16 Diseases of the respiratory system 17 Nasal catarrh (coryza, cold, snuffles, rhinitis) 17 Laryngitis 18 Pneumonia 18 Hemorrhagic septicemia (shipping fever) 20 Diseases of the skin 20 Eczema 20 Photosensitization (white-skin disease) 21 Sheep scab 21 Stiff lambs 22 Arthritis 22 Posterior paralysis 23 Muscular dystrophy (white-muscle disease) 23 Parasites 23 Stomach worms 23 Liver flukes 24 Immature fluke disease (black disease) 25 Tapeworms 26 Screwworms 26 Coccidiosis 28 Miscellaneous diseases 28 Abortion 28 Foot rot 28 Keratitis and conjunctivitis 30 Lambing paralysis 31 Laminitis (founder) 32 Mastitis 32 Navel infection 33 Urinary calculi 34 Poisoning 34 References for further reading 36 SHEEP DISEASES' H. S. CAMERON^ INTRODUCTION The economical production of livestock for market depends mainly upon breeding, environment, and nutrition. The prevention of disease, although superficially an entity, is intimately associated with these three factors. This publication will discuss sheep diseases, their various causes, and methods of control, particularly as related to herd management. Hygienic principles will be emphasized rather than specific curative agents, preventive vaccines, or bacterins, except those whose value has been clearly established. Disease con- trol in sheep is a problem of the group — not of the individual animal, as with a dairy herd or a stable of horses. The chief concern is whether the cause of death is apt to affect other animals and, if so, how the disease may be prevented from spreading. The exception to this rule is the purebred individual whose value may warrant veterinary service and costly drugs. This publication is not intended to supplant the local veterinarian. His assistance is recom- mended ; often it will result in early diagnosis and, therefore, in more rapid control measures. Diseases caused by internal parasites, such as stomach worms and liver flukes, or by poisonous plants have been discussed in recent l)iilletiiis'' and will therefore be mentioned only briefly. y . DISEASE IN GENERAL Before discussing specific diseases and their control we may well review certain general features of disease. These are (1) causes, (2) diagnosis, and (3) treatment and control. CAUSES OF DISEASE The causes of disease may be divided into two main groups : infectious and noninfectious. Infectious. — The infectious diseases are caused by a living germ or sub- stances invading the body, multiplying, and interfering with the normal functions. Since many are easily transmitted to other animals and may pro- duce an epidemic, this group is economically the most important. Some, like anthrax and lamb dysentery, are acute : they appear suddenl}^ run a short course, and terminate in death. Others, like caseous lymphadenitis and arthri- tis, are chronic : they develop gradually, continue indefinitely, and, though the actual death rate is low, cause losses through a failure to gain or reproduce normally. ^ This circular supersedes Extension Circular 86, Diseases of Sheep, by J. A. Howarth. The illustrations and some of the material used herein are taken from that publication wdthout citation reference. ^ Associate Professor of Veterinary Science and Associate Veterinarian in the Experi- ment Station. ^ Freeborn, Stanley B., and Morris A. Stewart. The nematodes and certain other parasites of sheep. California Agr. Exp. Sta. Bui. 603 : 1-75. 1937. Sampson, Arthur W., and Harry E. Malmsten. Stock-poisoning plants of California. Cali- fornia Agr. Exp. Sta. Bui. 593:1-90. 1935. Eevised 1942. [3] 4 California Agricultural Extension Circular 130 The cause of certain infectious diseases passes from one animal to another witli ease. Such diseases, called contagious, differ from those in which the living germ passes to others with considerable difficulty and perhaps requires an intermediate host such as a blood-sucking insect. In outlining a method of control, one must know how an infectious disease is transmitted. The causative agent may enter or be eliminated through a body opening or through any break in the skin. Biting or blood-sucking insects not infrequently transmit infectious disease-producing substances. Certain infectious agents are highly resistant: they form spores and can remain viable for years despite drying, freezing, high temperature, and milk disinfectants. Transferred to a favorable environment, they vegetate and produce disease. Anthrax is an example. Other agents are not resistant : on leaving the animal body they must speedily find another host or die. Resistance and Susceptihility. — Besides actual causes, certain factors may lower resistance and render the animal more susceptible to infection. Many germs that cause disease are continually in contact with the animal — on the skin, in the digestive tract, or even in the lungs. If the animal is constitution- ally sound, properly nourished, and maintained in a suitable environment, it may be able to resist these germs. Under faulty management the resistance is lowered ; and the germs, usually held in check, produce disease. Among the factors associated with lowered resistance are sudden change in feed, over- eating, overcrowding, lack of exercise, and inadequate shelter, and shipping over a considerable distance with inadequate feeding and watering. Noninfectious. — This group is composed of certain nonliving factors such as nutritional deficiencies, indigestion, poisons, injuries, climatic and atmos- pheric conditions, and lightning stroke. Noninfectious diseases, unless caused by serious nutritional disturbances or by the eating of poisonous plants, are apt to occur not as an epidemic but as individual cases. Occasionally, losses from mineral poisoning may be high. Such occurrences are rare, however, and are usually traceable to an obvious accident such as access to arsenic- sprayed vegetation, fertilizer, paint, or chemicals used in rodent control. Poisonous plants, which are usually poisonous only at certain stages in their growth, produce losses when consumed by stock which lack other feed ; they are widely known and are unimportant in comparison with the infectious causes. DIAGNOSIS Serious losses can be avoided by rapid, accurate diagnosis. Obviously, for example, if a disease caused by an infectious agent were diagnosed as a nutri- tional disturbance or as plant poisoning, control measures would be unsuc- cessful. In attempting to diagnose a disease, one should consider several fac- tors. The type of feed being consumed, the number affected, the swiftness or slowness of the onset, and the death rate will assist classification and may determine whether the disease is infectious or noninfectious. A sudden onset, with many animals affected, indicates either a contagious disease or a poison- ing. Under normal feed conditions, poisoning is rare and is readily detected. With a knowledge, therefore, of prevailing feed conditions and environment, poisoning, as the cause of disease, can usually be eliminated early in an out- break. Sheep Diseases 5 The rapidity of onset and the death rate are two invaluable aids in diag- nosis. Diseases such as anthrax and lamb dysentery are characterized by a sudden onset and a high death rate. Others like caseous lymphadenitis and arthritis have a slow onset and usually a low death rate. Certain diseases are seasonal: anthrax, for example, usually occurs in summer and early fall, whereas pregnancy disease of ewes occurs only before lambing. Symptoms. — Having, by the preceding observations, placed the disease within a certain group, one should next consider the symptoms. In an ex- tremely acute disease where death is sudden, symptoms may be entirely absent. When present, they may be divided into two types : (1) General symp- toms are those not specific for any particular disease, but found in many and not in themselves diagnostic. These include loss of appetite, dullness, un- thriftiness, emaciation, fever, stiffness, rapid breathing, and constipation or diarrhea. (2) Special symptoms indicate specific diseases or disturbances of specific orgap.s. For example, spasm of the muscles, whereby the limbs and neck are rigid, suggests tetanus or strychnine poisoning; a diarrhea showing fresh blood suggests coccidiosis. A swelling of the lymph glands at the shoul- der, flank, or head indicates caseous lymphadenitis. Autopsy. — Autopsy is among the most practical and reliable methods of diagnosing diseases of sheep and, except when anthrax is suspected, should be resorted to in confirming a diagnosis. If anthrax is suspected, the carcass should not be opened, for fear of contaminating the premises. Instead, the ear should be submitted to a laboratory for examination. The handling of sus- pected anthrax will be discussed later. Because decomposition starts early, especially in warm weather, autopsies should be performed promptly ; otherwise changes due to decomposition may be confused with the cause of death. Often, where several deaths have oc- curred, it is advisable to kill a sick animal that obviously will not recover. A carcass will bloat quickly, especially in a warm climate : therefore, unless observed before or immediately after death, bloating should not be considered as a cause of death. An autopsy should be systematic and complete, beginning with an exami- nation of the exterior and then working progressively through the lungs, liver, spleen, stomach, intestines, and bladder. Changes in these organs will be dis- cussed later as they apply to specific diseases. TREATMENT AND PREVENTION The practicability of treating a disease in sheep depends on the size of the band, the number affected, the value of the individuals, and the cost of the material. Some diseases would respond readily to treatment ; but the handling of a large band to treat a few individuals would frequently not be justified. Often, however, treatment must be resorted to on a mass scale, especially in parasitic infestations ; and if medicines are administered internally, certain precautions must be taken. If a drench is given the animal should be on its feet, struggling kept to a minimum, the head held in a natural position, and the liquid given rather slowly, preferably with a metal syringe. If the animal coughs, it should immediately be released. Failure to observe these precau- tions may lead to the fluid's entering the lungs, causing pneumonia. Capsules 6 CaltIfornia Agricultural Extension Circular 130 or pills should be administered with forceps or tongs and placed far back in the mouth over the tongue. When an individual must be given unusual medicines, veterinary service should be used if available. This statement applies particularly to sulfap\Tn- dine, sulfanilamide, and other drugs that under certain conditions may have bad effects. In managing a herd, one should observe certain principles in order to pre- vent disease. Good nutrition, including plenty of fresh water, is necessary for maintaining resistance at a high level. Corrals and sheds should be clean ; otherwise certain infectious diseases, particularly of lambs, may result. Sheds should be well ventilated, but free from drafts, and should allow sunlight to enter. They should be thoroughly cleansed each spring and, if possible, left idle at least part of the summer. Corrals should be free of manure and debris. They should be well drained, particularly around the watering troughs, where moist conditions are conducive to foot rot and to heavy infestations with stomach worms. One should carefully inspect any new animals lest they intro- duce disease. The herd should be observed daily, and sick animals immediately removed to other quarters; a disease should be considered contagious until proved otherwise. The cause should be ascertained especially when several animals are involved. If necessary, a veterinarian should investigate; or specimens should be examined at a diagnostic laboratory. Hopelessly sick animals should be destroyed, and carcasses so disposed of that they are not a disease-spreadinji' hazard. Dead animals should be burned, or deeply buried. Vaccines, Bacterins, and Serum.s. — These products will prevent some infec- tions, but are often used indiscriminately in instances where they are value- less. Their principle is based on the fact that when a disease-producing agent is injected, protective substances against that particular material are produced in the body. To be helpful, they must be prepared from the agent that causes the disease. Bacterins and vaccines differ distinctly from serums. The former are pre- pared from the actual cause of the disease and, when injected, produce pro- tective substances in the blood. These substances are effective only against the materials that caused them to be formed. Since 2 or 3 weeks are required to produce them in the body, bacterins and vaccine do not protect the animal immediately. Once attained, however, the protection is likely to last at least a year, depending on the disease. A serum is prepared by injecting an animal, usually a horse, with varying amounts of a disease-producing agent. After several injections the blood of the animal contains protective substances against that agent. The animal is then bled, and the serum used to protect other animals. Serum, since it con- tains the protective substances, gives immediate resistance, but only for 3 or 4 weeks. It is indicated, therefore, during an outbreak where immediate pro- tection is required. Bacterins and vaccines, on the other hand, are used, not during an outbreak, but where the disease may occur in the near future. Unfortunately, not all infectious diseases can be prevented by these prod- ucts. Relatively few can; and, even in these, protection is not complete. Vac- cination, accordingly, should not supplant precautionary measures involving Sheep Diseases 7 sanitation, and should be used only if proved reliable by authentic investiga- tions. No vaccine, bacterin, or serum should be tried unless the label shows that the laboratory operates under a government license. Such a label, how- ever, indicates only that the product is properly prepared, not that it will serve under all conditions. In many instances these products are bought solely on the advice of salesmen whose knowledge is superficial. While their improper use may do no actual damage, they constitute a needless expense and create a false sense of security. In the section on specific diseases, vaccination will be i-ecommended where it has definite value. SPECIFIC INFECTIOUS DISEASES ANTHRAX Anthrax is an acute infectious disease caused by Bacillus anthracis. It affects sheep, cattle, horses, swine, goats, and other species, including man. The causative organism is found in the soil in certain regions (so-called anthrax areas) and, being a spore-bearing organism, can remain dormant for years. In these areas the disease appears with varying severity, usually during the warm months. Mode of Infection. — Feeding on anthrax-infected pasture is the usual mode of infection. When this occurs a considerable number are affected. Occasion- ally, especially in early fall, single cases may be caused by flies that carry the germ and transmit it to animals in an anthrax-free area. The disease may also be spread by flesh-eating animals and birds carrying portions of anthrax carcasses that have not been properly disposed of. Never attempt to salvage pelts from dead animals where anthrax is sus- pected. Such practice spreads the disease to other animals and to man. Symptoms. — The onset of anthrax is sudden; and, since death occurs within a few hours, symptoms may not be observed. When seen they resemble those of other diseases and poisonings that cause rapid death. In sheep the disease progresses more rapidly than in other animals. The temperature is high at first (105° to 107° F.), respirations become greatly increased, breath- ing is labored, membranes appear blue, and the animal is restless. Toward death the temperature becomes subnormal, and convulsions and spasms are evident. Death may occur 2 to 24 hours after symptoms appear. Unless some other disease is present, anthrax should be suspected as the cause of sudden deaths, especially in the warm months and on land where anthrax has been previously diagnosed by laboratory methods. Autopsy. — The carcass undergoes rapid putrefaction. The skin may show some swelling; and blood may be exuded from the body openings. This blood, dark red and tarlike, shows little tendency to clot; it remains fluid for a con- siderable time after death. The spleen is usually swollen and hemorrhagic. Other organs may be inflamed, but often appear normal. The intestinal con- tents may be bloody because of extensive hemorrhages. The abdominal cavity may contain much yellowish-red fluid. Diagnosis. — A positive diagnosis can only be made by laboratory exami- nation of the blood. When animals are suspected of having died of anthrax the carcass should not be opened, because of the danger of infecting man 8 California Agricultural Extension Circular 130 and of permanently infecting the soil with anthrax spores. If possible a veterinarian should be consulted, and a specimen submitted to a laboratory for diagnosis. Where such services are unobtainable, remove an ear from the suspected carcass, wrap it in cloth dipped in disinfectant, place this in a jar having a tight cover, pack well in a box containing paper or sawdust to protect the container, and send it to a laboratory, together with information about the specimen. Control. — Because of the acute nature of anthrax in sheep, treatment is useless. Certain precautions, however, should be taken against its spread. When an outbreak appears, remove the stock from the pasture. Completely burn the carcasses, soil, or litter contaminated by discharges. Burial at a depth of 5 or 6 feet may be substituted when burning is impracticable. Knives and other objects coming in contact with the carcass should be boiled or placed in a strong disinfectant for several hours. The hands should, after washing, be rinsed with a strong disinfectant. Vaccines for controlling anthrax should be used with caution. Though they aiford protection, they contain living organisms and are dangerous. Their use should be confined to areas where anthrax actually exists and where sheep cannot be kept off the area during the warm season. If possible, the vaccine should be handled by a qualified veterinarian and administered in the spring so that immunity will be established before the warm months. It is important that empty vaccine bottles be burned to eliminate the possibility of infec- tion from this source. In California, anthrax must be reported to the State Department of Agri- culture, Bureau of Animal Industry. CASEOUS LYMPHADENITIS ( Pseiidotiiberculosis ) Caseous lymphadenitis, a chronic infectious disease of sheep and goats, is characterized by caseous abscesses, especially of the lymph glands, and is associated, in long-standing cases, with emaciation. Although more common in old ewes, it is not unusual in yearlings being fitted for show or sale. It has not been reported from the eastern United States, but is highly prevalent on the Pacific slope. It is among the most serious conditions encountered in the sheep-raising section of Australia. Economically it is important, not from the standpoint of mortality, but because lesions found upon inspection at abattoirs may, depending upon the extent, cause carcasses to be condemned as unfit for human consumption. Also an external lesion is an undesirable blemish in a ram submitted for sale. Cause. — The specific organism that produces caseous lymphadenitis is known as Corynehacterium ovis. Unlike the anthrax organism it does not form spores, is probably destroyed rapidly unless protected from unfavorable fac- tors, and is tlierefore not apt to persist indefinitely in the soil. On the other hand, tlie conditions whereby the organism may remain dormant or even multiply are present in most sheep sheds. This latter fact explains the high incidence of the disease in sheep being handled in sheds and corrals. The principal method of transmission is by wound infection, especially at shearing time. The presence of the disease in unshorn lambs suggests the open Sheep Diseases Fig. 1. — Large abscess in lymph gland just anterior to the shoulder, characteristic of caseous lymphadenitis. (From Ext. Cir. 86.) Fig. 2. — Ram affected with caseous lymphadenitis ; the scrotum, or bag, is greatly enlarged; the left side is com- pletely filled with pus. (From Ext. Oir. 86.) 10 California Agricultural Extension Circular 130 navel, docking, and castration wounds as paths of entrance. Infection may also occur through the mouth ; investigations at this station have occasionally revealed the organism in the ewe's milk. Symptoms. — Affected animals may remain in good condition, and the dis- ease be detected only after slaughter. Many will show no symptoms except a progressive emaciation and a dry, lifeless fleece ; others may exhibit painless swellings on the lymph glands, especially in front of the shoulder (fig. 1) and hip or upon the head. Sometimes the testicles are affected (fig. 2), one or both being often greatly enlarged. Frequently, when the lungs are involved, sheep exhibit a chronic cough ; the respirations are rapid and labored, while painful coughing or a nasal discharge may be present. Fig. 3. — Lamb affected with pustular dermatitis, show- ing affections of the outer surfaces of the face which are more or less free from wool, as the eyelids, exterior of the lips, and inside of the ears. (From Ext. Cir. 86.) Autopsy. — The carcasses of animals in the advanced stages of the disease may be poorly covered with flesh. Lesions are confined to the lymph glands, either the external glands or those in the chest cavity being usually affected. Occasionally the lung itself may be abscessed. The lesions, when cut through, may be somewhat gritty and will contain a greenish pus. The abscesses vary from the size of a millet seed to 3 or 4 inches in diameter. The capsules sur- rounding them are thick. The liver, spleen, and kidneys are occasionally affected. Treatment and Prevention. — External abscesses may be opened and drained, the incision being made large enough for complete drainage of the contents and for swabbing of the cavity with disinfectant. There is a slight danger that the opening of the abscess may admit the organisms to the blood stream and thus cause numerous abscesses in other parts of the body, par- ticularly the liver, with fatal results. Experiments at the California Agricul- tural Experiment Station have shown vaccination to be of no value. Sheep Diseases 11 Since the disease is primarily a wound infection, the disinfection of all wounds, especially at shearing, will materially reduce the number of cases. It is advisable, especially in infected flocks, to immerse the shearing head in disinfectant; also, to shear lambs first, and finish with the ewes. Sheep showing external lesions should be sheared last. When an abscess is ruptured, the shearing head should be immersed in disinfectant before proceeding with shearing. INFECTIOUS PUSTULAR DERMATITIS (Doby mouth, pox) Infectious pustular dermatitis in sheep and goats is a highly contagious disease characterized by blisters and scabs, usually on the mouth (fig. 3) but occasionally on the udder (fig. 4). It is observed in sheep and goats of all J Fig. 4. — The mammary glands of a ewe, showing pus- tules and scab formation in a case of pustular dermatitis. (FromExt. Cir. 86.) ages, but more often in lambs, and is caused by a filterable virus. In California it is not of serious economic importance; it occurs there sporadically, but does not spread through a band at such an alarming rate as in other areas. It is prevalent among lambs in Texas and is commonly recognized in lambs in the Rocky Mountain feed lots. In these feed lots it spreads rapidly, but usually subsides in 2 to 3 weeks. The mortality is low, and there may be no serious loss of condition unless the disease is complicated by a secondary invader, or unless the lamb is unable to nurse because of an infected udder on the ewe. Symptoms and Lesions. — The first lesions are a slight reddening and eleva- tion of the skin, followed by the development of vesicles containing fluid. As the vesicles increase in size, they become filled with pus. Eventually these I'upture, and a crust or scab forms over them ; this drops off by about the twenty-fourth day. The lesions are usually located on the lips and nostrils ; in more serious cases, upon the inside of the mouth. Continual rubbing may pro- duce a raw surface ; then secondary organisms enter, producing a more serious 12 California Agricultural Extension Circular 130 condition. In ewes tlie udder may become painful, and the lambs be prevented from nursing. Treatment. — Under normal conditions, animals will recover without treat- ment and apparently are immune to a second attack. In severe cases the scabs may be removed, and the affected parts treated with a nonirritating disin- fectant such as a chlorine preparation or a 2 per cent solution of potassium permanganate. In areas where the disease is prevalent and occurs annually in the lambs, the practice is to vaccinate all lambs against the condition at mark- ing. The procedure consists of making a small scratch on the inner surface of the thigh with a sharp-pointed instrument moistened with the vaccine. FOOT-AND-MOUTH DISEASE Foot-and-mouth disease is an acute, highly contagious disease caused by a filterable virus. The lesions are confined mostly to the mouth or feet, or both. The pathological changes are in the form of vesicles, resembling blisters and containing a clear yellow fluid. These rupture, leaving an erosion in the mucous membrane of the mouth or on the skin close to the hoof. The mouth lesions are observed usually on the gums, but sometimes on the lips and the roof of the mouth. Infectious pustular dermatitis in its early stages may resemble foot-and-mouth disease, but — unlike the latter — involves the pres- ence of pus in the lesions. Foot-and-mouth disease has not been reported in the United States since 1932. It is referred to here because of its highly contagious nature, the exist- ing danger of an outbreak, and the drastic measures necessary for its elimina- tion. When the disease is suspected, the State Department of Agriculture should be notified immediately. RABIES Rabies, an acute infectious disease, attacks all species of livestock. It is caused by a filterable virus that has an affinity for nervous tissue. The virus, present in the saliva of infected animals, is transmitted by biting. Infected dogs are the principal spreaders, although predatory animals, such as the coyote and the skunk, may also bring the disease to livestock. Affected sheep become irritable, aggressive, and easily excited. They may butt or hit other animals ; females may attack their own lambs. Later they become depressed and paralyzed. Death usually results in 3 to 5 days. Care should be exercised in handling suspected cases, for man may be infected if a wound becomes soiled with saliva. Suspected cases should be reported to the local health authorities, who submit the head of the animal to the state labora- tory for diagnosis. TETANUS (Lockjaw) Tetanus is an infectious disease, often fatal, characterized by rigidity of the muscles, and results from an infected wound. The cause is a toxin produced by Clostridium tetani — a sporeformer, highly resistant, almost universally distributed in the soil, and able to grow only in the absence of free oxygen. Wlien the organism enters a wound, particularly a puncture, ideal conditions are created for its growth; and, while growing, it liberates a powerful toxin that acts on the nervous system to produce a spasm of the muscles. The disease fSHEEP Diseases 13 may occur without observable wounds ; in such cases the wound was probably small and healed before symptoms appeared. It is occasionally observed after docking or castration, especially when the operation is performed on ground heavily contaminated with manure. The foi*mation of a scab over an untreated wound contaminated with soil provides conditions favorable for the organism. Symptoms. — The first symptoms are nervousness and a slight stiffness. The neck muscles become rigid, and the animal has difficulty in chewing and swallowing. Eventually the muscles become so stiff that the head is drawn back (fig. 5). Spasms of the facial and leg muscles are apparent; the limbs become rigid and extended. The animals are easily disturbed ; sudden noises give rise to convulsive spasms. Death occurs during the spasms. Fig. 5. — Lamb affected with tetanus (lockjaw). Spasms of the leg muscles cause them to be rigid and extended. Stiffness of the neck muscles causes the head to be drawn back. (From Ext. Cir. 86.) Treatment and Control. — When symptoms have appeared, treatment is useless. In the larger domestic animals susceptible to the disease, especially the horse, an injection of tetanus antitoxin is usually given after any deep wound. With sheep such procedure is not possible — a wound readily observ- able in the horse would probably be overlooked. Even in observed wounds, the expense of treating sheep with antitoxin would be too great. Docking and castrating on clean ground, and the rapid cleansing and disinfecting of all wounds, including the navel at birth, will decrease the danger of tetanus. DISEASES OF THE DIGESTIVE SYSTEM Probably the greatest losses in the sheep-raising industry result from dis- eases of the digestive tract and the associated organs. The causes are numerous, varying from dietary disturbances to parasitic infestations, and are more prevalent in lambs than in mature sheep. Losses begin in lambs at the age of a day or two with the highly fatal lamb dysentery. In feeder lambs, especially those recently placed on feed, losses may be high. Newsom and Cross* have * Newsom, I. E., and Floyd Cross. Feedlot diseases of lambs. Colorado Agr. Exp. Sta. Bui. 409:1-40. 1925. 14 California Agricultural Extension Circular 180 described several important diseases in feed-lot lambs, and some material in this section has been taken from their publication. LAMB DYSENTERY Dysentery is an acute, highly fatal disease of lambs 1 to 5 days old. It is more common in farm flocks, where lambing occurs in corrals and sheds, than under range conditions. Cause. — Several organisms have been incriminated, and the disease is prob- ably due to a variety of them. These organisms, in the soil or manure of sheds or eoralls, may contaminate the udder of the ewe. Lambs, highly susceptible at that age, become heavily infected when exposed to such conditions. Symptoms. — The disease may be so acute that the lambs die without show- ing symptoms ; some apparently normal in the evening may be found dead on the lambing grounds in the morning. Symptoms, if present, begin with depression and loss of appetite. Lambs refuse to nurse, lie on the ground most of the time, and show evidence of abdominal pain. The feces are fluidlike, brownish, and sometimes tinged with blood. Death occurs in 12 to 24 hours. Occasionally, the disease is more chronic and lasts 3 or 4 days before the animals succumb. Prevention and Control. — Because of the acute nature and short course, treatment is useless. Losses can, however, be checked by sanitation. As soon as the disease appears in a flock, remove the ewes yet to lamb to clean ground. This procedure will usually stop losses, but is not always practicable where climatic conditions do not permit lambing outdoors. To avoid using the same ground every year, some sheepmen have portable lambing sheds that can be readily moved. All sheds and corrals should be thoroughly cleaned after the lambing season and, if possible, left empty at least part of the summer. Car- casses should be buried or burned. Vaccination, advocated in some quarters as a preventive, has been of no value in this country because of the nonspecific nature of the disease. OVEREATING- (Pulpy kidney, enterotoxemia) Overeating produces an acute condition in lambs 6 to 8 weeks of age, al- though older animals in feed lots may also be affected; those attacked are usually in good flesh. The condition, called enterotoxemia by some, is fre- quently seen where young, green feed is abundant or where a heavy concen- trate ration is being fed, and is probably associated with indigestion from overeating. Cause. — The occurrence of the disease on rich feed indicates a primary digestive disturbance. The combination of a plentiful milk supply and lush, young green feed apparently produces an indigestion. Investigations have shown the intestinal contents of lambs dead of this condition to be toxic for experimental animals injected subcutaneously. Some consider a toxin pro- duced by anaerobes of the Clostridium welchii type to be the actual cause of death. These organisms, however, are usually present in the intestines and, under normal conditions, are harmless. When given experimentally along with the toxin they can safely be fed to normal lambs. They should therefore not be considered as a factor in the condition. Sheep Diseases 15 Symptoms. — Often death occurs without observable symptoms ; lambs ap- parently normal at night are found dead in the morning. Symptoms, when apparent, vary in individuals. They may consist of a staggering gait ; chewing of dirt, sticks, and such objects ; fast irregular breathing, bloat, and coma ; death within 3 to 4 hours. Sometimes the animals become dull; are suddenly seized with convulsions; exhibit violent movements, twitching of muscles, retraction of the head, grinding of the teeth, and frothing at the mouth. Death occurs in 1 to 4 hours. Occasionally blood is present in the urine. Diagnosis. — A history of numerous sudden deaths in lambs under the con- ditions described above is indicative of the disease. Autopsy reveals no charac- teristic lesions that are diagnostic. A soft pliable kidney, whence the disease derives its common name, is often, but not always present. Kidney degenera- tion starts soon after death from any cause and is not a true diagnostic lesion of enterotoxemia. The condition may be confused with "black disease." The latter, however, occurs only where the liver fluke is prevalent, and is associated with considerable liver damage. The ingestion of poisonous plants may pro- duce a similar condition. Such plants, however, are widely known and affect mature sheep as well as lambs. Botulism may produce comparable symptoms ; but being caused by a toxin formed under special conditions outside the body, it rarely occurs in sheep except under unusual feeding conditions. (See p. 35.) Control. — Since the onset of the disease is apparently influenced by over- eating, immediate steps should be taken to correct the feeding conditions. Lambs should immediately be removed from lush feed to pastures less rich. This procedure was adopted with marked success during several outbreaks in the Sacramento YaWey, but is often impractical, particularly in range bands, since the result would mean a delay in marketing lambs. The addition of dry feed, rich in fiber, may reduce the incidence. In feed lots where the condition is observed in newly introduced animals, it may be prevented by feeding lightly until the lambs have become accustomed to the change in diet or by reducing the grain and increasing hay when an outbreak occurs. INDIGESTION Indigestion is encountered more frequently in older lambs, especially those in feed lots. Causes. — Overeating is among the more frequent causes. Attempts to hasten the rate of gain in feed-lot lambs by increasing the grain allowances often cause indigestion. Overeating of unaccustomed, spoiled, or dirty feed may produce the disease. Indigestible substances such as hair, wool, or certain vegetable fibers may form balls in the stomach or intestines, hamper the free passage of material, and, not infrequently, cause fatal indigestion (fig. 6). Symptoms. — Symptoms vary with the cause and the severity of the disease. Sometimes, especially when the cause is overeating, the onset is sudden. Some animals may stagger, fall, and die in convulsions within a few minutes. Others may live a few hours, showing nervous symptoms. The actual cause of death in these cases is not clearly understood. According to Newsom and Thorp,' it may be related to enterotoxemia. ^ Newsom, I. E., and Frank Thorp, Jr. The toxicity of intestinal filtrates from lambs dead of overeating. Amer. Vet. Med. Assoc. Jour. 93(3) : 165-67. 1938. 16 California Agricultural Extension Circular 130 Dullness, loss of appetite, bloating, scouring, and loss of condition are the usual symptoms of indigestion. These may continue for a day or two, and be followed by spontaneous recovery. If the symptoms persist, the result is emaciation and death. Treatment and Prevention. — Sick lambs should immediately be segregated, and feed concentrates withheld until marked improvement is noticed. Green feed or well-cured alfalfa hay in limited amounts, with abundant clean water. Fig. 6. — ^Wool balls (actual size) removed from the paunch; the consistency of these bodies reminds one of felt. (From Ext. Cir. 86.) should be available. If the procedure is practicable, 1 to 2 ounces of Epsom salts or castor oil is advisable. When recovery is well under way, light feeding of concentrates, using oats or bran, may be started. In preventing the condition, avoid sudden changes in feed. Lambs intro- duced into feed lots are fatigued, and many are unaccustomed to grain. They should be fed lightly until they are acclimated and have become accustomed to the type of feed. To prevent gorging, distribute the grain evenly in the troughs. In fattening lambs on grain, there is a tendency to force feed. Sucli animals should be observed carefully for evidence of going off feed ; and, at the first sign, reduce the amount of grain and increase the hay. BLOAT Although bloat is a symptom of indigestion, its importance as a source of loss in livestock warrants a separate description. Sheep Diseases 17 The condition is encountered chiefly on irrigated pastures of alfalfa fu- el over, and results from the consumption of large quantities of easily fei-- mented food, especially feed low in fiber. Gas, in excess of what the animal can dispose of by belching, is rapidly produced in the rumen and, without relief, will quickly result in death. Since a carcass will bloat quickly, especially in warm weather, bloating should not be considered the cause of death unless observed in the living animal. Treatment and Prevention. — One ounce of Formalin or turpentine is an antiferment and will stop further gas formation. If the bloat is mild, further- treatment may not be necessary ; if it is severe and the animal shows distress, puncture of the rumen may be necessary. Puncture can be performed with any available clean sharp instrument, but more satisfactorily with a trocar and canula. The trocar is a round, sharp- pointed instrument; the canula a sleeve that fits over the trocar. When the puncture is made, the trocar is withdrawn ; and the canula, remaining in the wound, allows gas to escape freely to the outside rather than to the abdominal cavity. It is advisable to introduce an antiferment into the rumen through the canula after the gas has escaped. The treatment of bloat is not practicable in feeder lambs on Ladino clover if large numbers are involved. Certain practices in handling stock in an en- vironment conducive to bloat will materially decrease losses. Less bloat is observed when lambs are on pasture containing a relatively high percentage of grasses mixed with clover. Coarse feeds, apparently by stimulating the lining of the stomach, cause belching and thus prevent bloat. Wet areas should be avoided, especially if the feed is luxuriant. Pastures should not be ex- tremely lush or overgrown. Lambs should not be moved in the hottest hours of the day. Those on their back should be given immediate assistance, since they will bloat and die within a short time. Fat lambs should be moved very little and marketed as soon as possible, since they are highly susceptible to bloat. DISEASES OF THE KESPIRATOHY SYSTEM Respiratory diseases are important, not only from an economic standpoint, but because they often indicate that resistance has been lowered either through faulty management or by unavoidable circumstances. Many such diseases can be traced primarily to unsatisfactory environment and nutrition. Biologies (serums, vaccines, and bacterins) are widely used in their treatment and prevention; but, since most of the conditions are nonspecific as regards the causative agent, the value of these preparations is doubtful. NASAL CATARRH (Coryza, cold, snuffles, rhinitis) Nasal catarrh is an inflammation of the upper air passages and sinuses. It is usually acute, subsiding in 7 to 10 days, but sometimes chronic, persisting indefinitely. The disease itself is relatively mild but, if neglected, may extend to other organs and produce more serious trouble. Cause. — The condition, usually infectious, is frequently predisposed by exposure to cold, especially during cold and damp weather, and in sudden 18 California Agricultural Extension Circular 130 climatic changes. It is seen in animals after shearing, dipping, or shipping over a considerable distance. It is also a symptom of acute infections of other respiratory organs such as the larynx, bronchi, and lungs. Dust, foxtail or barley awns, larvae of the sheep botfly {Oestrus ovis Linn.), smoke, or gases irritate the mucous membranes and may also produce nasal catarrh. Symptoms. — Nasal discharge is the distinctive sign. It begins as a thin clear fluid and later becomes thick and yellowish. The animal is dull, and the appetite poor. The mucous membranes, including those of the eyes, are in- flamed. Frequent sneezing is apparent. Treatment. — In the acute condition, protection against chilling, moisture, and fatigue usually results in rapid improvement. The affected animals should be separated from the healthy and placed, if possible, in a dry shelter free from drafts. They should be lightly fed good alfalfa hay or, if possible, fresh green feed, and should have abundant clean water. If this procedure is adopted at the onset, extension of the condition into laryngitis, bronchitis, or even pneumonia may be prevented. Medicinal treatment is of little value unless the animal is constipated ; in such cases an ounce or two of Epsom salts is recommended. Serums or vaccines are valueless. LARYNaiTIS Acute laryngitis may result from neglect of nasal catarrh. It may also occur primarily from exposure to severe conditions after shearing or dipping. The chief symptom is a short, dry, painful cough, easily induced by pressure on the throat. Although more serious than nasal catarrh, the condition will usually be cleared up by similar procedures. A type of laryngitis in which the mortality is high occurs under certain con- ditions. It has been observed mostly in purebred registered yearlings being fitted for show or sale. Though the primary cause is unknown, an organism, Corynehacterium pyogenes, has been isolated from several cases. Injury to the mucous membrane of the larynx, perhaps by awns or grain, is probably a predisposing factor. The first apparent symptoms resemble those of acute laryngitis. They rapidly increase in intensity ; and, as the larynx becomes inflamed, the open- ing decreases, and breathing becomes difficult and noisy. There is a hoarse, dry, painful cough. Death from asphyxiation occurs in 3 to 7 days. On autopsy the larynx appears greatly inflamed, swollen, and clogged with fibrinous material. Ulcers or scars may be present on the mucous membrane; often, when the swollen area is cut, a pocket of greenish pus will be found. There is no satisfactory treatment. PNEUMONIA Pneumonia is an inflammation of the lungs. It occasions serious losses in sheep, particularly in young lambs, and is produced by a variety of factors. Causes. — There are several possible causes : (1) Exposure to sudden changes ill temperature, fatigue, shearing followed by cold or damp weather, and shipping reduce the natural resistance of the body and permit infection. (2) No specific organism has been proved the cause of pneumonia in sheep. Although several organisms have been isolated from diseased lungs the PneumocQCCUS, which causes pneumonia in man, has not been found in do- Sheep Diseases 19 mestic animals. Many of the organisms associated with pneumonia of sheep are usually able to produce the disease only if natural resistance has been lowered. (3) Inhalation of foreign substances or improper drenching with liquid medicines is the most frequent cause of mechanical pneumonia. It results from administering the material too fast, while the animal is strug- gling, or through holding the head too high. Recovery from this type is rare. (4) A heavy infestation of lungworms, coupled with poor management and nutrition, may block portions of the lungs and eventually cause pneumonia. (5) Pneumonia may occur secondary to other diseases that prostrate the animal. In these cases, death is often due to pneumonia rather than to the original disease. In animals that have been down for a considerable time, par- ticularly on one side continuously, the lungs become congested; and unless the animal is moved, pneumonia will result. Symptoms. — The rapidity of onset is variable. Usually it is gradual. Occa- sionally, especially in lambs, it is rapid, and death is sudden. The first symp- tom is dullness and loss of appetite. The temperature rises, and breathing becomes faster. The mucous membranes of the nose and eyes become reddened, and a nasal discharge may be apparent. There is a hard, dry, painful cough. The respiratory symptoms increase in intensity ; breathing is fast, difficult, and wheezy. The termination of the disease depends on the cause, the extent of lung damage, and the stage when treatment was instituted. In secondary and inhalation pneumonia, the possibilities of recovery are poor. In the uncompli- cated disease, if treatment is initiated before the lung damage becomes exten- sive, the outlook is favorable. Autopsy. — The lesions of pneumonia at autopsy are distinct. The larynx will probably show congestion. The trachea and bronchi are inflamed and usually contain white or red-tinged froth or pus. The lungs, normally pink and spongy, are dark reddish brown and solid. The pleura (the membrane lining the chest cavity) may adhere to the lungs; the cavity usually contains considerable red-tinged or straw-colored fluid. Treatment and Prevention. — Successful treatment of pneumonia depends on recognizing the disease early and caring for the animal. At the first symp- tom the animal should be separated from the flock, placed in a dry shelter free from drafts, and disturbed as little as possible. Veterinary service should be enlisted if the animal is valuable or if many animals are affected. Treatment using expectorants and other drugs that will make breathing easier may be helpful in the early stages. Laxatives, such as mineral oil or Epsom salts, should be used if necessary. In a few cases, good results have been secured with sulfathiazole. This drug, because of the toxic action from continued use, should be used under veterinary direction. Because of the nonspecific nature of pneumonia in sheep, antiserum has little or no value. The prevention of pneumonia depends on sound management. Shipped lambs, on arrival, should be carefully handled. They are fatigued and should not be driven immediately or placed on heavy feed concentrates. Green feed, if available, should be given ; if not, good alfalfa hay may be lightly fed. Abundant clean water should be available. Sheep should not be dipped late in the afternoon when there is no chance of drying before nightfall. If cold 20 California Agricultural Extension Circular 130 or damp weather follows shearing, shelter should be provided. Cases of minor respiratory diseases may often be saved from pneumonia by special care and protection from exposure. Bacterins have been widely used to prevent pneumonia. Since, however, the cause varies and since bacterins are specific only for certain organisms, they are of little value. No well-controlled investigations have been reported For preventing pneumonia by using biologies alone. HEMORRHAGIC SEPTICEMIA (Shipping fever) ''Hemorrhagic septicemia" is a much abused term applied to respiratory or digestive diseases and used as a diagnosis when the true cause is not apparent. The condition frequently so called is characterized by loss of appetite, dull- ness, jerky breathing, rise in temperature, cough, and nasal discharge. The cause in sheep is said to be Pasteurella oviseptica. This organism can be found, however, in normal as well as sick animals ; and there is no evidence, other than finding the organism, to show that it is the cause of the disease. There is invariably a history of animals' being subjected to unfavorable factors, such as shearing or change in environment, before the appearance of symptoms. Since the same symptoms can be due to a variety of organisms, and since most cases will recover spontaneously under good management, vaccination is not justified from the standpoint of cost and effectiveness. A diagnosis of hemorrhagic septicemia, unless made by a competent veteri- narian and supported by autopsy and laboratory findings, should not be accepted as the basis for the use of biologies of no value in the particular instance. The condition is mentioned here because of indiscriminate diagnosis by persons interested only in selling vaccines, and because of the widespread use of such products in its name. DISEASES OF THE SKIN ECZEMA This inflammatory condition, commonly called "summer sores," is charac- terized by intense itching ; certain parts of the body may be denuded by biting. The disease usually starts in the early summer, gradually grows worse during the hot weather, and subsides or completely disappears during the fall and winter. The areas most generally involved are over the loins, on the sides of the abdomen, behind the shoulders, and occasionally under the abdomen (fig. 7). The cause is unknown; but the disease does not appear to be con- tagious, for many bands will have only one or two affected animals, and Ileal thy sheep in close contact with those having summer sores do not contract it. Feed and sunlight are evidently not contributing factors as in photo- sensitization. Symptoms. — In the early stages, sheep bite or gnaw at the flank, scratch and rub against some object, or try to scratch certain parts with the hind feet. Occasionally they exhibit an itching or irritation of the ears or legs ; and soon raw, bleeding areas appear. The affected parts gradually become larger and are continually irritated by flies. Sheep Diseases 21 Treatment. — "Wash the affected area with a fairly strong solution of cresol dip (6 ounces in 1 gallon of water), allow it to dry, and apply a thick coating of pine tar or other fly repellent. Because of the action of the animal in rub- bing the area, the treatment may have to be repeated several times. PHOTOSENSITIZATION (White-skin disease) This inflammation of the white portions of the skin not protected by wool is considered to be a reaction to light after sensitization of the animal by sub= stances contained in a number of plants. Bighead or swelled head, frequently found in sheep in the Rocky Mountain area, is apparently a photosensitization. Fig. 7. — Summer-sore sheep showing denuded areas caused by con- tinual biting. (From Ext. Cir. 86.) Symptoms. — The first indication is a swelling of the ears, eyelids, and lips, with intense itching (fig. 8). In severe cases the skin under the ears becomes distended with clear fluid, which finally oozes out and adheres to the surface. Later the swellings decrease in size, and brownish scabs can be seen scattered over the surface. Treatment. — Except in advanced cases, recovery will usually result if shade is provided or if the affected animals are removed to other pastures. SHEEP SCAB Sheep scab, caused by a mange mite, was formerly prevalent and caused serious losses in the West. Quarantine and dipping have largely eradicated it, and outbreaks are now only sporadic. The mites puncture the skin, irritate, and cause considerable rubbing and biting. The lesions are usually observed on the back and sides. Crusts and scabs form; the wool falls out, leaving bare areas. Untreated animals lose condition and die. Lime-sulfur dip is effective in destroying the mite. The entire flock should be dipped, and the treatment repeated 14 days later. Suspected cases should be reported to the State De- partment of Agriculture. 22 California Agricultural Extension Circular 130 STIFF LAMBS Stiffness in lambs may accompany several diseases and is usually the symp- tom of a more obscure disorder. Many intestinal, respiratory, urinary, or nervous disturbances interfere with the free movements of the limbs and pro- duce stiffness. Shipping over a considerable distance or a sudden change in feed and environment frequently results in the sickness of a number of lambs. Such animals will show stiffness and a dull, unthrifty appearance. Most con- ditions included under stiff lambs can be prevented or reduced in number by sanitary precautions and proper management, particularly durin'g lambing. Fig. 8. — Oozing of serum from the affected ears in photosensitization (white-skin disease). (From Ext. Cir. 86.) Besides nonspecific stiffness, certain diseases — arthritis (inflammation of a joint), paralysis, and white-muscle disease — may directly interfere with the joint or muscles and cause a stiffness. ARTHRITIS Arthritis, chronic inflammation of a joint, is characterized by lameness and swelling in one or more joints. Affected lambs walk stiffly, move only when urged, and gradually lose condition. Although death losses are not high, the animals fail to gain and are often stunted. A post-mortem examination may reveal lesions only at the joints, with all other organs appearing normal. The joints are thickened and contain an abnormal amount of thin fluid or, in a few cases, pus. In severely affected lambs the ends of the bones may be eroded. Cause. — The condition may be produced by various types of bacteria, but frequently by Erysipelothrix rhusiopathiae, the same organism that causes erysipelas in swine and turkeys. The bacteria enter the body through a wound, are carried in the blood to the joints, and localize in the joint cavity. The un- treated navel at birth, or wounds from castrating and docking, provide en- trances. The infection may remain dormant in the body for some time and Shef]p Diseases 2o later become active, producing the disease suddenly in older lambs in feed lots. Arthritis is more common in farm flocks, where lambing is conducted in sheds and corrals, than under range conditions. Prevention. -^Treatment is of no value in arthritis of lambs, and it is not profitable to attempt raising animals that show the symptoms and swellings. The infection in a flock may be materially lessened by sanitary precautions at birth and marking. Clean sheds and corrals will also reduce the incidence of the disease. As soon as possible after birth, the navel should be disinfected with tincture of iodine, which not only disinfects, but by its astringent action aids in rapid healing. Castration and docking wounds should be disinfected, and the lambs placed on clean ground until the wounds have healed. POSTERIOR PARALYSIS Posterior paralysis, occasionally seen soon after docking, results from an infection entering through the stump of the tail. The infection localizes in the spinal cord, paralyzing the hind quarters. If paralysis is complete the affected lambs have no use of the hind limbs and must drag them when mov- ing. If it is incomplete, a stiff or awkward gait may be the only symptom. The measures recommended for preventing arthritis apply also to paralysis of the hind quarters. MUSCULAR DYSTROPHY (White-muscle disease) Muscular dystrophy is apparently much more prevalent in the eastern states than in the West, though it has been reported from Oregon. Lambs 1 to 5 weeks old are affected — often the best lambs in the flock. At the onset the lamb has difficulty in rising, tires rapidly, and later has great difficulty in walking. Severely affected lambs become thin, emaciated, and unable to nurse ; they die of starvation. Autopsy shows characteristic white areas in the muscles ; usually the hind limbs are involved, and almost invariably the same muscles on both sides of the body are affected. The cause is unknown. Apparently the disease is neither infectious nor hereditary. Evidence points to a nutritional cause. Treatment has not been successful ; and, until the cause is known, specific preventive measures cannot be undertaken. PARASITES The important internal parasites of sheep, having been described by Free- born and Stewart,* will be referred to only briefly. STOMACH WORMS Sheep are particularly susceptible to stomach-worm infestation, and serious losses occur in bands maintained under conditions favorable to these pests. The life cycle of the parasites is relatively simple; eggs are passed in the feces and, under favorable conditions of moisture and warmth, develop into infec- tive larvae. These larvae, ingested by the animal while grazing, complete their development in the stomach or small intestines, where they live and continue *^ Freeborn, Stanley B., and Morris A. Stewart. The nematodes and certain other para- sites of sheep. California Agr. Exp. Sta. Bui. 603: 1-75. 1937. 24 California Agricultural Extension Circular ]30 to deposit eggs for at least two years. Irrigated pastures, especially clover that requires frequent irrigation, provide ideal conditions; more larvae survive there than on dry range or stubble. High concentrations of stock, as in Ladino^ clover areas, progressively increase the degree of pasture infestation. The damage produced by internal parasites depends primarily on the number of larvae ingested and upon the individual lamb's resistance and condition. Symptoms. — The symptoms of internal parasitism are not in themselves diagnostic. Failure to gain normally, rapid loss of condition in severe cases, anemia, diarrhea, and submaxillary swelling suggest parasitism. Post-mortem examination of a dead or sacrificed animal is the most reliable method of diagnosis. The stomach lining is usually inflamed, and the parasites will be found in large numbers. The two predominating stomach worms found in the western states are small and not readily observed. Ostertagia, the larger, can be seen with the naked eye in stationary material under a good light. Trichostrongylus requires some magnification; but if the organism is present in large numbers, agitation of the contents of the abomasum will be observed when the material is placed in a stationary container under a good light. Treatment. — Several methods are available for treating sheep parasitized with stomach worms. These are phenothiazine, a 1 per cent copper sulfate (bluestone) and 1 per cent nicotine sulfate mixture (commonly called cunic mixture), and tetrachloroethylene. Phenothiazine is the most effective; is available in tablets, powder, or suspension ; and is administered to parasitized animals in a dose of 12 to 15 grams for lambs and 25 grams for mature sheep. It is not necessary to withhold feed before treatment. A dose of this size colors the urine and may dye the wool, a disadvantage in some instances. Pheno- thiazine, because of its low toxicity as compared with other remedies, can be administered to the flock as a whole rather than to individuals : usually, 1 part of the drug is mixed with 10 to 15 parts of coarse salt, and the sheep are allowed free access to the mixture. When animals are in good condition and not heavily parasitized, the method prevents the development of stomach worms, and is widely used in lambs on permanent pastures where parasitism is inevitable. On the other hand, sheep showing symptoms of parasitism should be given a single full dose, followed by the salt-mixture routine. Cunic mixture is given as a drench with a metal dose syringe in amounts of 2 ounces for lambs and 4 ounces for mature sheep. Tetrachloroethylene is usually given in a gelatin capsule in a 5-cubic-centimeter dose. It is advisable to withhold feed several hours before giving these two remedies. A common practice is to corral the stock for one night, treat in the morning, and then turn the sheep to feed immediately. LIVER FLUKES Liver-fluke disease exists chiefly in certain swampy areas west of the con- tinental divide and occasions heavy losses through death, unthriftiness, and condemnation of livers. In California it is found in the counties of the Coastal Range, the Siskiyou Mountains, and the Sierra Nevada. It does not exist in the Great Valley, although animals imported into that area for feeding may harbor flukes in the bile duct for some time. In the absence of an intermediate host (a fresh-water snail) the disease does not become established. Sheep Diseases 25 The life cycle of the fluke is more complicated than that of the stomach worm. Eggs pass in the feces, and under favorable conditions young flukes (miracidia) are hatched out. These swim about in swamps in search of the intermediate host. Unless this snail is found, the miracidia die in 24 to 48 hours. After further development, lasting 50 to 80 days, they leave the snail's body, become attached to vegetation, and are ingested by the final host, the sheep. In the intestines they burrow through the wall, penetrate the liver, and eventually reach the bile ducts, where they attain maturity 2 to 3 months after being ingested. The heaviest losses from flukes are often due to the migration of immature flukes from the intestines to the liver. Bacteria, normally harmless in the intestines, are carried to the liver, where they produce disease. Losses are caused directly by destruction of the liver tissue and by hemorrhage from ruptured blood vessels. Symptoms. — The symptoms in heavily infested animals resemble those of other parasitisms : dullness, anemia, weakness, loss of appetite, edema of the lower jaw, dryness of the skin and wool. The symptoms may persist for months, followed by death or recovery. Diarrhea is often a final symptom. Treatment. — Treatment with carbon tetrachloride (flukoids) given as a 1-cubic-centimeter dose in a gelatin capsule or mixed with 4 cubic centimeters of paraffin oil and used as a drench will destroy mature flukes in the bile duct. Because it is not effective against immature flukes migrating through the liver, it should be repeated in 2 to 3 weeks. As long as sheep are maintained on snail-infested pastures, carbon tetrachloride should be given throughout the summer at intervals of about 2 months. The drug is usually safe for sheep ; but occasionally bad results may ensue, especially if the animals are receiving rich concentrates, are excessively fat, or have reached advanced pregnancy. It is advisable, especially in using the drug for the first time, to dose a few animals as a trial before treating the remainder of the flock on the following day. Prevention. — Since the developing fluke will die unless it finds the inter- mediate host, the disease can be effectively controlled by a snail-elimination program. The draining of swampy areas where the snail exists is the ideal method, but in most instances the size of the area presents an insurmount- able difficulty. Copper sulfate (bluestone) in dilutions of 1 part to 1,000,000 parts of water is toxic to the snail and harmless to livestock. Small sacks of copper sulfate may be suspended in the water at the head of a snail-infested stream. In the treatment of marshland, 1 part of the powdered copper sul- fate should be mixed with 4 parts of sand or dry soil and broadcast over the area. The procedure may have to be repeated in about a month to kill snails hatched in the interval. If possible, snail-infected pastures should be fenced off. IMMATURE FLUKE DISEASE (Black disease) Black disease is an acute infection associated with liver-fluke infestation. Where flukes are present, the disease causes heavy mortality. In Australia, where the trouble is common, losses range from 16 to 60 per cent of the band. In California the disease is limited to coastal and mountain counties and is not encountered in the Great Valley. 26 California Agricultural Extension Circular 130 Cause. — The actual cause of death is apparently a toxin produced by Clostridium novyi, an organism normally present in the intestinal tract, Avhere it is harmless. Immature flukes passing- from the intestines to the liver mechanically carry these organisms with them. In this habitat the organisms multiply and produce the toxin. Symptoms. — As in other conditions caused by toxins, the onset is sudden; death occurs so rapidly that symptoms are not observed. Animals apparently normal in the evening may be dead by morning. Dullness, lagging behind the flock, and fast shallow breathing are usually the only symptoms ; death fol- lows about an hour after symptoms appear. Autopsy. — Since decomposition occurs early, animals must be examined immediately after death. The abdominal cavity contains a variable quantity of straw-colored fluid. The most typical lesions are found in the liver, which is dark and congested, usually showing a few punctures where the immature flukes have penetrated. Yellowish necrotic areas appear throughout the organ and are the chief lesion. They are roughly circular and are % to 1 inch in diameter. Prevention. — Since black disease is associated with liver flukes, the first essential is to rid pastures of the parasite. This measure is discussed in the section on liver flukes. Since carbon tetrachloride is effective only against mature flukes in the bile duct, whereas black disease is associated with immature flukes, medicinal treatment for flukes will not prevent the trouble. In 1930, reports from Australia indicated that vaccination was successful. In 1938, the Montana Agricultural Experiment Station also reported favorable results with a toxoid prepared against the causative organism. Within the past year that product has been used in California and, according to reports, with success. Vaccination is of value, however, only against black disease. It does not pre- vent liver-fluke infestation and is of no value against secondary invaders other than Clostridium novyi. TAPEWORMS Moniezia expansa, the broad tapeworm, is found in the Coast Range coun- ties ; but, although the infestation may appear heavy, it is not an important factor in sheep raising in California. In the Great Valley the parasite may persist in feeder lambs imported from coast counties, but certain factors not yet understood prevent the spread in this area. The lambs fatten normally ; losses actually due to overeating are often falsely attributed to the tapeworm because of post-mortem findings. The tapeworm may, under poor nutritional conditions, increase the unthrif tiness ; but it does not produce sudden death such as occurs in overeating. Cunic mixture as recommended for stomach- worm infestation (see p. 24) will effectively control this tapeworm, and it should be used on infested lambs. SCREWWORMS The screwworm fly is among the most important external parasites en- countered in the livestock industry of the Southwest. Although usually con- fined to that section, it occasionally penetrates farther north and, in some Sheep Diseased 27 years, occasions serious losses in areas where it is not normally present. The name is derived from the habit of the larvae in penetrating into the living tissues of the animal. The fly, unlike the common blowfly, prefers to lay its eggs in a fresh wound where there is living tissue rather than on decaying flesh. Eggs so deposited, under favorable conditions of temperature and moisture, hatch out larvae in 1 to 2 days. The larvae immediately burrow into the tissues, reach maturity in about a week, and drop to the ground. There they reach the pupa stage, from which flies emerge in from 1 to 2 weeks, depending on the prevailing conditions. Even minor wounds such as scratches, barbwire, or shearing cuts are sub- ject to strike. The open navel is also subject; and, without treatment, death may result. Occasionally, in sheep, strike may occur at the corner of the eye without an observable wound. Since flies are also attracted to wounds already infested with larvae, there is little likelihood of spontaneous recovery. Treatment and Prevention. — In treatment of affected sheep, the larvae must first be destroyed, and the wound protected from further strike. Com- mercial benzol is the most efficient material now available for destroying larvae. It is relatively nonirritating to the tissues and is low in cost. Absorb- ent cotton saturated with benzol is inserted in the wound and kept there at least 3 minutes. Dead larvae should be removed, provided the operation can be accomplished without causing additional hemorrhage. A fly repellent should then be added to the wound. Several repellents are available; they usually contain either pine tar or bone oil. Some have benzol incorporated with them. The wound must be reexamined in not more than 48 hours. Recently a chemical known as diphenylamine has been recommended by the United States Bureau of Entomology and Plant Quarantine to prevent the development of larvae in wounds. This material will not destroy larvae already present, nor will it repel flies. Eggs will be deposited in its presence, but the young larvae as they hatch are destroyed. Diphenylamine is a gran- ular powder; after the larvae have been killed by benzol, the powder is tamped into the wound. Besides destroying young larvae as they hatch out, this material has the additional advantage of retaining its action somewhat longer than either tar or bone oil. It is usually effective for 3 days; and, unless the wound is extensive, healing will have occurred over this period. Research by the United States Bureau of Entomology and Plant Quaran- tine' has resulted in a mixture of diphenylamine, benzol, turkey-red oil, and lampblack. This remedy is known as smear 62. It has the consistency of thin paint, kills screwworms or other fly maggots quickly, and protects against reinf estation for several days. In screwworm areas all wounds should be treated with a fly repellent or diphenylamine. To keep the fly population down, carcasses must be burned or buried deep, especially in areas where the fly appears only in certain years and in limited numbers. Unless such precautions are observed, the parasites may become permanently established in a section where winters are not always severe enough to destroy the fly. ^ Gushing, E. C, and D. C. Parman. The screwworm and blowfly problem. In: Keeping livestock healthy. U. S. Dept. Agr. Yearbook of Agriculture 1942:313-22. 1942. 28 California Agricultural Extension Circular 130 COCCIDIOSIS Coccidiosis is an infectious disease prevalent in feed-lot lambs. The causa- tive organism is a protozoan often found in small numbers in the feces of apparently normal animals. The life cycle is complicated, but a part of it may take place outside the animal body. Oocysts (spores) are passed in the droppings. Under favorable conditions of moisture and temperature they reach the infective stage and, when ingested, continue the life cycle in the intestines. There they enter the cells of the mucosa and produce hemorrhages that may, depending on the number of organisms present, be severe. Unlike the stomach worms, coccidia may multiply within the intestines several times before going into the free-living stage. The disease can spread widely through a flock or may affect only a few animals. The severity of the outbreak de- pends upon the species of coccidia involved and upon the environment of the flock. Symptoms. — A persistent bloody diarrhea is a characteristic symptom. Lambs lose their appetite and are greatly depressed; they rapidly become emaciated, anemic, and feeble. Death may occur in a week after the appeaj-- ance of symptoms. A positive diagnosis is made by examining feces under the microscope for oocysts. Treatment and Prevention. — The affected animals should immediately be separated from the healthy. Treatment with astringents such as tannic acid and bismuth is of doubtful value and is not practicable where fairly large numbers are involved. Many lambs will recover if moved to dry quarters and given access to light feed, preferably well-cured hay. Normal animals may carry a limited number of coccidia and pass oocysts in the feces. When the numbers become excessive, clinical symptoms appear. Since infection takes place by the mouth, contamination of feed and water must be avoided. Feed troughs should be free from droppings, hay fed so that it is not trampled on, and the water supply kept clean. MISCELLANEOUS DISEASES ABORTION Abortion is relatively uncommon in sheep as compared with cattle. The abortion rate in a flock may be abnormally high during a certain year ; but, since this trouble is rare and sporadic in the western states, its cause has not been investigated. Various organisms, the commonest being Vibrio fetus, have been found associated with the condition ; apparently they do not produce a highly contagious disease. FOOT ROT Foot rot is a chronic wound-infection disease, characterized by extreme lameness and frequently by distortion of the hoof (figs. 9 and 10) . It is appar- ently more prevalent in wet pastures and is important economically not because of the death rate, but because of the large numbers affected and the loss of condition through lameness. Cause. — Irritation by mud which dries and cracks the skin, by sand, and by gravel between the claws, especially if there is an overgrowth of hoof, pre- Sheep Diseases 29 Fig. 9. — The lack of wear on the hoof causes it to be overgrown and distorted, the weight being thrown on the outer wall of the foot. (From Ext. Cir. 86.) disposes to infection and is the primary cause of foot rot. A variety of organ- isms may be involved. They are appar- ently harmless to the normal foot and should be considered secondary in- vaders. Symptoms. — At first there is a slight lameness, which rapidly becomes marked. Animals badly affected may walk on three legs; or, if the forefeet are affected, they will rest on their knees, especially while grazing. The hoofs become overgrown and distorted. Much of the horn becomes undermined and detached from the underlying tissues. Occasionally the hoof appears normal ; but when pressure is applied to the sole, pus exudes from a narrow, deep opening. The primary lesion is the reddening and swelling, accompanied by a moist discharge between the two claws of the hoof. The skin between the claws is bare and may show raw, ulcerated areas. As the infection progresses, the more sensitive structures of the hoof beneath the horriy layers become affected; the hoof becomes detached in places ; and an inflammatory discharge of offensive odor is given off. Treatment. — At the first outbreak the affected animals should, if possible, be segregated, and the others passed through a solution containing 1 pound of copper sulfate (bluestone) to a gallon of water, deep enough to cover the feet. Usually this treatment will prevent further spread and is sufficient to check mild cases. In severely affected animals the diseased hoof must all be thoroughly trimmed — the most important part of the treatment. Then a disinfectant should be applied to kill the organism. In severe cases, disinfection is valueless unless the foot is trimmed so that the disinfectant can reach the infecting organism. Several types of disinfectants may be used ; because of low cost and efficiency, those with a cresol base are satisfactory. Compound solution of cresol, a stand- ard preparation, may be used in proportions of 4 ounces to a gallon of water. Copper sulfate, 1 pound to a gallon of water, is also effective and cheap. On no account should a strong, irritating substance be used. The object is to prevent irritation and i)romote healing. A disinfectant incorporated in lanolin (wool fat) has the advantage of adhering longer. A disinfectant in fluid form penetrates better, however, and Fig. 10.^ — ^The horn becomes under- mined and detached from the underly- ing tissues in old, chronic cases of foot rot. (From Ext. Cir. 86.) 30 California Agricultural Extension Circular 130 should be used in deep abscess formations where only a narrow opening is present. In such cases it may be necessary to flush the wound out with a syringe after cleaning and paring as deeply as possible. Where practicable, a pack kept saturated with a disinfectant in hot water may be used. Some owners immediately market affected lambs even if the animals are not in top condi- tion. If treated, the lambs would lose weight, and the ultimate cost of handling would be greater than if they were sold at the onset of the disease. KERATITIS AND CONJUNCTIVITIS These two conditions, both called "pink eye," often occur simultaneously. Since treatment is identical, they will be considered together. Conjunctivitis is an inflammation of the mucous membrane lining the eye cavity ; keratitis is an inflammation of the cornea of the eye. Fig. 11. — Ewe affected with conjunctivitis, showing soiled and matted wool, due to lacrimation (watering from the eye). (From Ext. Cir. 86.) Cause. — The causes are divided into two groups: (1) An infectious agent is often responsible and may spread rapidly through a flock. (2) Irritants such as foxtail, thorns, grass seed, and awns also produce the condition. Symptoms. — The first symptoms noticed are a flow of tears, which soils and mats the wool. The animal partially closes its eyes to avoid light. The eye membranes become congested and reddened. As the affection progresses, the cornea becomes involved ; instead of clear and transparent, it appears hazy and blue (fig. 11). Occasionally ulcers, first appearing as white spots, form on the cornea and may even penetrate it, causing rupture of the eyeball. In severe cases, especially of the infectious type, permanent blindness may result. Prevention and Treatment. — Unless the condition is obviously due to an irritant, the affected animals should, if possible, be segregated from the re- mainder of the flock to prevent further spread. If a foreign body is present, it should be removed. Whatever the cause, the eye should be treated with one of the following preparations. , Sheep Diseases 31 1. Pyoktanin blue, 1 to 10,000 dilution. This material, though inexpensive and efficient, is a dye, a fact that may, because of wool stain, be detrimental. 2. Two per cent ammoniated mercury ointment. This ointment is inexpen- sive and antiseptic. Being nonirritating, it is preferred over the yellow oxide of mercury. The ointment is contained in collapsible tubes. Only enough should be used to cover the cornea ; an excess leads to accumulation of dust or other irritating materials around the eye. 3. Ten per cent Argyrol. This, if freshly prepared, is efficient, but more expensive than the others. Since it deteriorates rather rapidly on standing, it is less practical than the other remedies. Treatment should be continued at least once daily until the cornea becomes clear. Most animals recover in 1 to 2 weeks. If the eyes are left untreated, ulceration of the cornea and permanent blindness may ensue. Though infec- tious keratitis bacterins are available, their value is doubtful ; the response to treatment is so marked that their use is not justified. LAMBING PARAIiYSIS Lambing paralysis, a disease with a high mortality, affects ewes about 2 to 3 weeks before lambing. It occurs under a variety of conditions in farm flocks, but has not been observed in range bands. It is usually associated with twin pregnancy. Cause. — The cause is unknown. The disease is not infectious, but is consid- ered to be a disturbance of metabolism, whereby the assimilation of certain food elements, probably carbohydrates, is interfered with. Lack of exercise has been considered a cause ; but since the disease does not occur in some closely confined flocks, exercise is apparently only one of several factors that may be involved. The disease occurs in animals on alfalfa as well as on concen- trates. A sudden change, such as taking ewes off pasture, confining them, feeding them rather heavily, and permitting only limited exercise, appar- ently tends to produce the condition. The influence of pregnancy is unknown ; but as the condition is usually associated with twin lambs, pregnancy evidently plays an important role. Symptoms. — The first sign of the disease is dullness and loss of appetite; animals drag behind the flock, lie down, and rise only when urged. Although the eyes appear normal, the ewes are blind. Finally they go into a coma and die in 2 to 4 days. A laboratory examination of the blood shows a low sugar content. On autopsy the characteristic lesion is a yellow friable liver in which an abnormal amount of fat has been deposited. Almost invariably, twin lambs will be found in the uterus ; or, if not, a large single. The carcass is often in good flesh, but sometimes may be emaciated. Prevention and Control. — The cause being unknown, no definite recom- mendations regarding prevention can be made. On the appearance of the disease in a flock, a change in management is indicated. Exercise should be enforced, either by driving the animals or by hauling the feed to remote parts uf the pasture. In some flocks good results have been reported from feeding molasses before lambing. Sudden changes in environment and feeding habits before lambing should be avoided if possible. 32 Californta Agricultural Extension Circular 130 LAMnsriTis (Founder) Laminitis, an inflammation of the sensitive tissue of the foot, causes intense pain that makes walking difficult or impossible. The front feet are usually affected, but occasionally all four. Cause. — The condition may be caused by overeating, especially of concen- trates; by digestive disturbances from sudden changes in feed; or by the consumption of excessive water after being deprived of water. The severe pain is caused by congestion of blood in the feet. Symptoms. — Lameness is the first symptom. Affected animals will shift or raise the feet because of intense pain from the slightest pressure or weight. The animal will be down much of the time and will rise only when urged. Treatment. — Since constipation is usually associated with the condition, a laxative such as 4 ounces of Epsom salts should be administered. Food con- centrates should be removed, and light feeding with green feed substituted. Cold applications on the affected feet tend to reduce the inflammation ; this treatment is best accomplished with wet packs soaked several times daily. MASTITIS Chronic Mastitis. — Usually this chronic inflammation of the udder is due to an infectious agent and follows injury or mishandling. Exposure of the udder to excessive chilling, dampness, filth, or injury predisposes to infection by bacteria. The initial attack may be acute ; the udder becomes swollen, hot, i-ed, and painful. The animal goes off feed and appears dull. The udder secre- tions may be watery and yellowish, or may contain solid puslike particles. Often an offensive odor is apparent. In 2 to 3 days the animal becomes normal, and the condition in the udder chronic. Solid nodules replace glandular tissue, and milk production is lowered. This chronic type of mastitis is rarely fatal, but the rate of gain in lambs may be lowered because of the diminished milk supply. Hot applications, massage, and the milking out of the udder early in the condition give favorable results. Gangrenous Mastitis. — This type, known commonly as blue bag, is a serious condition in ewes. It is characterized by a blue-violet color of the greatly swollen udder. It usually terminates in a fatal septicemia (blood poisoning). In almost all cases the disease is confined to one half of the udder. The ani- mal goes off feed, appears dull and weak, has a high temperature, and walks Avith a stiff, straddling gait. As the condition progresses, the affected portion of the udder becomes greatly swollen, cool, insensitive, and dark blue. The swelling may extend along the abdomen. The secretions become dark reddish brown and have an offensive odor. Affected animals should be segregated immediately. Treatment with sulfanilamide, 30 grains in tablets three times daily, in the early stages of the disease has been reported successful. In the absence of medicinal treatment, surgery is necessary to save the animal. The leat is amputated close to the udder, and a large incision is made to allow drain- age. Anesthesia is unnecessary; the diseased tissue is insensitive to pain. The gangrenous or dead tissue will slough off and expose an extensive wound that heals slowly, leaving the unaffected half of the udder in good condition. Sheep Diseases 38 NAVEL INFECTION The unhealed navel of the new-born lamb resembles an open wound, pre- senting an entrance for disease-producing agents. Common among these arp the pus-producing bacteria. The result of such infection may only be localized inflammation. On the other hand, the infection may enter the circulating blood, be transferred to various organs, and produce a septicemia (blood poisoning), abscesses, or other lesions. The condition is prevalent only in farm flocks and is rare in range bands. Symptoms.—Sympioms usually appear 6 to 8 days after birth. Lambs affected will generally show a slight disturbance such as dullness, general Fig. 12, — Small abscesses scattered throughout the liver in a case of navel ill. (From Ext. Cir. 86.) depression, disinclination to move, and lack of appetite. Occasionally the respirations are rapid and short. Lameness suddenly appears ; one or more joints, especially the knees, are swollen, hot, and painful. Loss of condition is very rapid ; the lambs show little desire to suckle or feed and are found lying down most of the time. The navel may be wet, and the wool around the part may be matted and soiled with discharges from the affected area. Autopsy. — The liver and lungs are the organs most commonly involved. The liver is light brown, and abscesses are numerous throughout the organ (fig. 12). Abscesses are not uncommon in the lungs and may vary from the size of a millet seed to that*of a baseball; they are filled with a grayish-yellow pus. The joints may contain much yellowish fluid and, in the older lambs, a thick yellowish-green pus. Prevention. — Treatment is unsatisfactory. Prophylactic measures, how- ever, are effective in preventing the condition. One can greatly reduce the number of eases by saturating the navel and the surrounding area with tinc- ture of iodine as soon as possible after birth, and by lambing on clean ground. 34 California Agricultural Extension Circular 130 URINARY CALCULI Urinary calculi in sheep are mineral deposits, usually composed of calcium phosphate or calcium carbonate. Calculi mostly affect wethers and rams ; they accumulate in the bladder and kidneys and are passed down with the urine, blocking the urinary passage. The voiding- of urine is interfered with ; com- plete stoppage may result. The cause is unknown, but probably is dietary. Affected sheep stand around with the back arched. They show frequent straining and attempt to urinate, passing only a few drops of blood-stained urine. They become dull and lifeless, going off feed or eating very little; as the condition progresses, they lie down most of the time. The wool around the stieath becomes matted and wet; dropsical swellings usually appear on the abdomen before death. The urine, completely or partially retained, is soon absorbed into the system, ruining the meat for use. If the calculi are not removed, rupture of the bladder occurs, followed by death. Since the cause is unknown, control measures cannot be suggested. POISONING Poisoning is comparatively rare in domestic animals and can usually be diagnosed after an investigation of the environment and the feed. A tendency exists, however, to attribute obscure losses to it. Few poisonings can be diag- nosed by clinical symptoms alone ; yet a chemical analysis of stomach contents is costly, impracticable, and inadvisable unless there is sufficient evidence to justify analysis for a particular poison. Arsenic. — The source of arsenic poisoning in domestic animals is material sprayed for the purpose of controlling insects, weeds, or rodents — for ex- ample, paris green, white arsenic, sodium arsenite, or sodium arsenate. The onset of arsenic poisoning is sudden, with marked depressions as shown by groaning, restlessness, and rapid breathing. Death may occur in 3 to 4 hours or, if less material is consumed, in a few weeks. Autopsy shows a severe hemor- rhagic inflammation of the stomach and intestines, with perhaps areas of erosion on the mucous membranes. Lead. — Since lead is not readily eliminated from the body, small doses accumulate until poisoning results. Arsenate of lead, an insecticide in orchards, and the oxides of lead in paint, are the common sources. The symp- toms resemble those of arsenic poisoning, with the addition of excitement. Poisoned animals may walk in circles and run blindly into objects. Nitrates. — Nitrate poisoning is encountered less frequently than arsenic or lead. It occurs in animals that accidentally gain access to nitrate fertilizer. The poisoning ends fatally in a few hours. Copper Sulfate. — Overdosing with copper sulfate (bluestone), or the use of too concentrated a solution in treating parasites, is a not infrequent form of poisoning. Symptoms such as severe abdominal pain, vomiting, and diar- rhea appear soon after the material is administered. Then follow collapse and convulsions. On autopsy the stomach and intestines appear intensely inflamed, and the stomach lining is coated with the copper sulfate. Copper sulfate should not be given under any circumstances in a concentration greater than 2 per cent. Four fluid ounces of a 1 per cent solution is the maximum dose. Sheep Diseases 35 Strychnine. — Strychnine poisoning occurs not infrequently in domestic animals, either from an overdose of drugs containing strychnine, or from the consumption of poisoned grain laid out for rodents and other pests. Strych- nine is one of the few poisons recognizable from the symptoms. The sudden onset is characterized by severe muscular spasms. Limbs, back, and neck are held rigid. Relaxation may take place, but the slightest sound or touch will stimulate another seizure. The spasms suggest tetanus; but with tetanus the onset is gradual, whereas in strychnine poisoning the jaws are rarely involved, and the course is very short. Botulism. — Botulism, a rapidly fatal disease, results from the ingestion of toxin produced outside the animal body by the anaerobic spore-forming or- ganism Clostridium hotuUnum. The toxin is frequently present in decomposed animal and vegetable matter, but is not found within the living animal. Inves- tigations have shown that tightly packed damp hay containing CI. Botulinum may become toxic. The only apparent symptoms are weakness and paralysis, terminating in death in a few hours to 3 days. Sheep at times will run blindly into fences and other objects. No effective remedy is known ; the use of specific antitoxin or toxoid, though effective, if administered before the symptoms appear, is not practicable in domestic animals. 36 California Agricultural Extension Circular 130 REFERENCES FOR FURTHER READING Britton, J. W. 1943. The use of phenothiazine for the treatment of stomach and intestinal worms. 2 p. California Agr. Ext. Leaflet. January, 1943. Dorset, M. 1931, Some common disinfectants. U. S. Dept. Agr. Farmers' Bui. 926:1-10. Dykstra, E. K 1942. Animal sanitation and disease control. P. 1-546. The Interstate Publishing Com- pany, Danville, Illinois. Freeborn, Stanley B., and Morris A. Stewart. 1937. The nematodes and certain other parasites of sheep. California Agr. Exp. Sta. Bui. 603:1-75. Imes, M. 1935. Sheep scab. U. S. Dept. Agr. Farmers' Bui. 713 : 1-29. Mead, S. W., John Britton, and H. H. Cole. 1944. Cause, prevention, and treatment of bloat. 2 p. California Agr. Exp. Sta. April, 1944. (Litho.) Miller, Robert F. 1939. Creep-feeding of spring lambs. California Agr. Exp. Sta. Cir. 348:1-10. Miller, Eobert F. 1942. Sheep production in California. California Agr. Ext. Cir. 49 : 1-79. Revised. Newsom, I. E., and Floyd Cross. 1925. Feedlot diseases of lambs. Colorado Agr, Exp. Sta. Bui. 40'9:l-40. Pope, G. W. 1933. The disinfection of stables. U. S. Dept. Agr. Farmers' Bui. 954:1-12. Shahan, M. S. 1943. Diseases of sheep and goats. U. S. Dept. Agr. Farmers' Bui. 1943 : 1-59. Wilson, J. F. 1937. Wool production and improvement of the clip in California. California Agr. Ext. Cir. 106:1-61. 20w-9.'45(4784)