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Domestic Rabbits Diseases and Parasites

A Pacific Northwest Extension Publication Oregon • Idaho • Washington Archival Copy. For current information, see the OSU Extension Catalog:https://catalog.extension.oregonstate.edu Contents

Factors in disease prevention Fungal diseases ...... 18 and control ...... 4 Parasitic diseases ...... 19 Body soundness and livability...... 4 Adequate nutrition...... 4 Prevention and control...... 19 Suitable environment...... 4 External parasites...... 20 Prevention, eradication, and control Ear mites...... 20 of transmissible diseases...... 5 Fur mites...... 20 Sanitation program...... 5 Cuterebrid flies...... 20 Disinfection...... 6 Fleas and ticks...... 21 Practices to maintain health and Internal parasites...... 21 prevent disease...... 7 Coccidiosis...... 21 Encephalitozoonosis...... 22 Bacterial diseases ...... 7 Toxoplasmosis...... 23 Pasteurellosis...... 7 Roundworms...... 23 Rhinitis (snuffles)...... 7 Tapeworms...... 24 Pneumonia...... 8 Nutritional diseases ...... 25 Pyometra...... 8 Orchitis...... 9 Pregnancy toxemia...... 25 Otitis media...... 9 Vitamin A deficiency...... 25 Subcutaneous abscesses...... 9 Vitamin E deficiency...... 25 Septicemia...... 9 Hereditary diseases ...... 26 Enteritis...... 9 Glaucoma...... 26 Enterotoxemia...... 9 Malocclusion...... 26 Mucoid enteropathy...... 10 Splay leg and ataxia...... 26 Tyzzer’s disease...... 10 Coccidiosis...... 11 Miscellaneous ...... 27 Listeriosis...... 11 Cannibalism...... 27 Necrobacillosis...... 11 Heat prostration...... 27 Salmonellosis...... 12 Broken back...... 27 Staphylococcosis...... 12 Sore hocks...... 28 Mastitis...... 13 Tumors...... 28 Conjunctivitis (weepy eye)...... 13 Fur eating and hairballs...... 28 Treponematosis (vent disease)...... 13 Coprophagy...... 29 Hutch burn...... 14 Yellow fat...... 29 Pseudotuberculosis...... 14 Winter breeding depression...... 29 Tularemia...... 14 How to pack and ship specimens Viral diseases ...... 15 for laboratory diagnosis ...... 29 Myxomatosis...... 15 Shipping dead animals...... 29 Rabbit pox...... 16 Accompanying information...... 30 Fibroma...... 16 Herpes virus infection...... 16 Rabbit papilloma...... 16 Oral papilloma...... 16 Viral enteric diseases...... 17 Viral hemorrhagic disease...... 17

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Domestic Rabbits: Diseases and Parasites N.M. Patton, K.W. Hagen, J.R. Gorham, and R.E. Flatt

Domestication of the Euro‑ been improved from the long, Rabbit raising has continued pean rabbit probably occurred in rangy, low‑meat‑yield type to the to be a backyard or part‑time monasteries during the Middle compact, blocky animal of today. business. However, the size of Ages. By the middle of the 17th The offspring of one doe the herds has expanded from a century, rabbits were commonly yield more than 120 pounds of few does to the current average raised in England and continen‑ meat per year, and 200 pounds rabbit herd of 20 does, and it is tal Europe. Oryctolagus cuniculus, per doe is not unlikely in the not uncommon to see herds of one of the more successful mam‑ future. Feed required to pro‑ 300–500 breeding does. mals of the world, is both pro‑ duce 1 pound of meat has been Commercial rabbitries aver‑ lific and adaptable. reduced from about 6 pounds to aging fewer than 30 rabbits per Most of the fancy breeds were 3.5 or 4 pounds. cage per year (sent to market) developed within the past During the past 10 years, the find it very difficult to show a 100 years, and only since the rabbit industry has expanded profit. Typically, the profitable early 1900s have rabbits been considerably. It may not, as yet, commercial number is more raised domestically in the United have reached the popularity it than 40 rabbits per cage per year. States. The first commercial experienced during World As in all facets of agriculture, colonies were started in southern War II. But the nutritional the profits from rabbit raising California. Meat rationing dur‑ ­qualities of rabbit meat are depend a great deal on manage‑ ing World War II gave the infant ­making rabbit more acceptable, ment and market. If an area has industry a push. and production is increasing. a steady demand for rabbit meat Today, approximately and a stable processor, the rab‑ 200,000 people are engaged in bit farmer can net a reasonable some phase of the rabbit business profit and add to the family in the United States, and animals income. are produced in every state. Meat processors serving major cities Nephi M. Patton, director emeritus, market more than 10 million Rabbit Research Center, Oregon State University; Karl W. Hagen (deceased), pounds of rabbit meat annually. bacteriologist, and John R. Gorham, Over the years, the breeds have veterinarian, Agricultural Research Ser‑ vice, U.S. Department of Agriculture, Pullman, Washington; and Ronald E. Flatt (deceased), veterinarian, Depart‑ ment of Veterinary Pathology, Iowa State University. Revised in 2007 by John Harkness, professor emeritus, Mississippi State University. This publication is a revision of USDA Agriculture Handbook 490, originally published in 1976. It was prepared with the support and permission of the Agricultural Research Service.

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The difference between profit from disease—is a better source ­rabbits. A simple change to a and loss often comes down to of replacement stock than a diet higher in fiber and lower in a person’s ability to master the rabbit that does not show these energy gives adequate growth husbandry and disease control traits. without the risk of enteric techniques necessary for success. Healthy, well‑framed, well‑ ­disease. The only rabbit that will fleshed mature does producing On the other hand, does need return a profit to its owner is a litters containing from 8–12 live adequate energy for reproduc‑ healthy one. This publication is young, with low mortality at tion, which may not be pro‑ designed to help ranchers recog‑ 8 weeks, good feed conversion, vided by diets extremely high in nize the more common rabbit and high weights are potential fiber. Progressive rabbit raisers diseases and to know when pro‑ sources of breeding stock. Care‑ now feed two diets, one to the fessional advice is needed. Dis‑ fully examine each individual growing fryers and another to eases are classified according to selected for breeding. Look for the producing does. A simple major cause—bacterial, viral, defects and general health, and diet that provides good health, nutritional, hereditary, fungal, eliminate animals that deviate growth, and production is pre‑ and miscellaneous (including from normal. Through rigid ferred but often difficult to find poisoning, tumors, and vices). application of this practice, a because the needs of the various profitable, high-producing herd classes of rabbits are considerably can be established. different. Factors in disease Inadequate nutrition is a prevention and Adequate nutrition costly problem. A general decline control in health may increase suscepti‑ Feeding is the most important bility to diseases, which can lead Factors conducive to good husbandry technique in the to large monetary losses. In health include body soundness rabbitry and should be done by addition, young rabbits grow and livability; adequate nutri‑ an experienced person. Most slowly if the doe has inadequate tion; suitable environment; and disease and potential disease milk or they do not get enough prevention, eradication, and con‑ problems are discovered during feed. Thus, feeding is a criti‑ trol of transmissible diseases. feeding time. Some disease prob‑ cal element in successful rabbit lems can be corrected by chang‑ ­raising. Body soundness ing the amount or type of feed. and livability Much has been learned in the past few years concerning rab‑ Suitable environment Sound, vigorous rabbits are bit nutrition. Diets that produce The term “environment” necessary both as quality meat good growth in poultry and includes every factor that influ‑ products and as replacement swine are disastrous in rabbits. ences a rabbit’s life. Some of stock. Carefully examine the Rabbits are foraging animals that these factors are hutch size and background of animals saved for live on grasses and seeds in the location, nearness to other ani‑ breeding so that recognizable wild. Their digestive system and mals, dryness, temperature, ven‑ defects are not perpetuated. A its microbes do not adapt well to tilation, amount of light, shelter healthy, mature breeder—one high-energy, cereal‑grain diets. design, availability of water, and that has a history of several litters In fact, diets high in starch general management. Careful showing fast development, good examination and control of the reproduction, high livability of and carbohydrates often cause diarrhea and death in fryer environment are essential for the young, and relative freedom effective disease prevention.

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Prevention, the presence of Pasteurella, but ronment plays an important part eradication, and ­cultures usually cost too much to in the time interval involved. control of transmissible be used routinely. Sanitation program diseases Mechanical transmission of A constant sanitation pro‑ disease occurs when the infec‑ gram is an important part of If disease prevention has failed tious agent is carried accidentally disease prevention. Cleanliness is and transmissible diseases are from place to place. People are required to establish and main‑ established in a rabbitry, high the chief offenders. The grower tain a safe environment in which mortality may lead to business who treats a sick animal and animals can live and reproduce. failure. Growers commonly then moves on to check or count Elimination of disease carriers is encounter pasteurellosis, ear newborn young can be an most important. mange, and coccidiosis. These important carrier of respiratory Environmental factors must infectious diseases usually are infection and coccidiosis. Feed introduced by contact with be considered in any sanitation salespeople, service representa‑ program. Unfavorable environ‑ infected rabbits or by contami‑ tives, rabbit buyers, and others nated mechanical carriers. mental factors lower animals’ who have visited other rabbitries resistance to disease and facilitate Pasteurellosis and liver coc‑ may be sources of infection. the spread of infection. Particu‑ cidiosis are important diseases Avoid visiting other rabbitries larly important are hutch and spread by contact. Adult rabbits where disease is present. These shelter construction and mainte‑ examples might seem extreme, are the most important contact nance (Figure 1, next page). Ease carriers. An animal may seem to but they happen repeatedly and of cleaning, a supply of clean recover from a disease but still are definite factors in introduc‑ water, and space for rodent‑proof shed infectious organisms in its tion of disease. Dogs, cats, birds, feed storage are important. feces, urine, or in droplets and rodents have been incrimi‑ Proper drainage is another factor. exhaled while breathing. Intro‑ nated in carrying diseases to rab‑ Provide for water runoff from ducing new stock directly to a bits and should be kept out of the rabbitry area. Construct herd or exhibiting animals at the rabbitry. Insects also should hutches so that individual units shows and fairs increases the risk be controlled. may be removed for disinfecting. of disease outbreaks. Keep new When disease prevention fails, Adjust the number of animals or exhibition animals in a special you must consider how to con‑ per unit based on the area and isolation section of the colony trol and eliminate the disease. the environment. until you are reasonably certain When liver coccidiosis is they are disease‑free. This quar‑ Water should be fresh, clean, involved, the adult carrier may and protected from contamina‑ antine period usually is at least be freed from infection by che‑ 2 weeks. tion by urine, fecal matter, and motherapy, but improved man‑ feeds. It is important to clean Carriers of disease often are agement practices are the only water containers frequently. not recognized because they way to eliminate the disease from Feed contaminated with feces seem healthy. Tests to pinpoint the herd. which animals are carriers are may act as a mechanical car‑ In some cases, it may be nec‑ rier for infection. Protecting the not always practicable. Liver coc‑ essary to depopulate to eliminate cidiosis is found when the fryer feed from contamination by the a disease. The time between use of properly designed and is dressed out for market, too depopulation and repopulation late to trace back to the doe that well‑constructed feed hoppers with clean, healthy animals is necessary in any good sanita‑ produced it. Bacterial cultures depends on many factors. Envi‑ of the nasal cavity may show tion program. Clean feeders ­periodically.

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no disadvantages to using this method of sanitation except that coccidial oocysts might not be killed. Another disinfectant used by some rabbit breeders is lye water. One 13-ounce can of lye is enough to make 15 gallons of cleaning and disinfecting solu‑ tion. For large ranches, it is advisable to buy the lye in the form of caustic soda. Each pound makes about 20 gallons of solution. Heating is advisable but not necessary. In addition to acting as a disinfectant, lye cuts grease and partly dissolves and penetrates fecal material. Figure 1.—Shed construction suitable for mild climates. Use of lye has some disad‑ vantages. Concentrated lye is a Good feed utilization and effectiveness of even the most poison and damages aluminum waste removal are important in efficient disinfectants. Thorough paints and clothing. The lye disease prevention. Feed scat‑ scraping and washing should may be slightly irritating to the tered about the rabbitry attracts precede disinfection. hands and face of the operator. insects, mice, rats, and birds—all A solution of sodium Consequently, take precautions potential carriers of disease. Store hypochlorite (bleach) is both to avoid excessive exposure of bulk feed properly. In small rab‑ effective and economical for dis‑ the skin during the disinfecting bitries or where large quantities infecting cages, nest boxes, and process. Keep containers of lye of bulk feed are not stored, metal ancillary equipment. Make the tightly covered. garbage cans with tight lids are solution by adding an ounce of Some ranchers use steam good feed-storage containers. bleach to a quart of water. Place under pressure to clean and the solution in a spray bottle and disinfect pens and equipment. Disinfection spray it on the equipment to be When using steam, first soak Disinfection refers to the kill‑ sanitized. caked fecal material with water. ing of infectious agents such as Cages generally are sprayed Use of a good cleansing com‑ bacteria, viruses, and parasites. after rabbits are sent to market pound, followed by steam, cleans To facilitate the use of disinfec‑ and before the next occupants and disinfects satisfactorily. tants, all equipment and other arrive. Spray feeders and water‑ Sunlight is a potent disinfec‑ construction should be as simple ing devices at the same time. tant if equipment is very clean and easy to clean as possible. Clean and wash nest boxes and sufficient exposure time is Fecal matter and other organic before spraying with the solu‑ allowed. A cement slab exposed material protect disease‑ tion. You can soak or rinse to the direct rays of the sun is a producing bacteria, viruses, removable equipment in the good place to disinfect movable and parasites and nullify the hypochlorite solution. There are equipment.

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Flaming or burning cages with ­determine the cause. The follow‑ ­rabbits to a diagnostic labora‑ a propane torch to remove hair ing course of action is suggested: tory or your local veterinarian. does not sanitize the cage 1. Mark or note pens that con‑ 5. Destroy all hopelessly sick because the wires are not heated tain sick animals. animals and bury or burn all to a sufficient temperature to 2. Isolate sick animals. If pos‑ dead animals. Open disposal destroy the organisms. Be careful sible, keep them in rooms pits are not recommended. not to singe rabbits when burn‑ or buildings separate from 6. Clean and disinfect all pens ing hair. This procedure also is a healthy rabbits. before placing new rabbits in fire hazard. 3. Care for the sick animal only them. after all other rabbits in the Practices to maintain herd have been cared for to pre‑ health and prevent vent carrying infection from Bacterial diseases disease sick to healthy rabbits. Be sure Pasteurellosis to wash hands and disinfect Successful growers practice “Pasteurellosis” is the designa‑ boots after caring for sick good sanitation and manage‑ tion for all diseases associated animals. Clean and disinfect ment, feed an adequate diet of with Pasteurella multocida. The any equipment moved from simple ingredients, and give their disease manifestations are varied an area where there are sick animals plenty of fresh water. and include rhinitis (snuffles), animals to the pens containing pneumonia, pyometra, orchi‑ It is important to inspect all healthy animals. animals in the herd each day. tis, otitis media, conjunctivitis, 4. If you cannot determine the When you first notice sick subcutaneous abscesses, and cause of the trouble quickly, rabbits, immediately try to ­septicemia. send a few typically sick Rhinitis (snuffles) The mucous membranes of the nasal sinuses become infected by bacteria from inspired air or by direct contact with infected animals or contaminated objects. The clinical disease is character‑ ized by nasal sounds and by a catarrhal (mucus or pus) nasal discharge (Figure 2). The extent to which the infection spreads into the lower respiratory pas‑ sages depends on the virulence (invasiveness) of the bacteria and the susceptibility of the animal. If the disease is confined to the upper passages, the first signs are sneezing followed by a nasal dis‑ charge. The inner aspects of the rabbit’s forepaws may be caked with exudate because of attempts Figure 2.—Adult showing signs of snuffles. Note discharge from nose. (The large dewlap is normal on this animal.)

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to wipe the exudate away from residues might remain in the bluish eye color in albinos, and a the nose. treated rabbits’ meat for days or nasal discharge. The body tem‑ Pasteurella bacteria often are weeks, making the meat unus‑ perature usually is above normal. found in the nasal sinuses of able for human consumption. Gross lesions of the lungs healthy‑looking rabbits. Stress Penicillin use may cause fatal appear as red consolidated areas, resulting from extremes of tem‑ ­enterotoxemias. sunken purple areas, and perature, high humidity, high If the nasal discharge regresses, abscesses. The consolidated ammonia levels, travel, preg‑ take care not to stress the rabbit. lesions most often are in the nancy, and lactation is a primary It should not be used as a anterior lobes of the lungs factor in the development of breeder. The next stress period (Figure 3). A catarrhal exudate is snuffles. (e.g., kindling, lactation, heat found in the air passages. Treatment of snuffles has not wave) very likely will cause the Abscesses appear with thin, proven to be economically effec‑ symptoms to reappear. Vaccines fibrous capsules close to the tive in commercial rabbitries. By have not proven to be effec‑ surface of the lungs. Sometimes using broad-spectrum antibiot‑ tive. The only effective method there are adhesions between the ics such as oxytetracycline or of control is strict culling. If a wall of the chest cavity and the chlortetracycline, the symptoms rabbit has a nasal discharge or lungs. might be alleviated. However, matted paws or sneezes on 2 Pneumonia rarely is treated in the animal often remains a car‑ consecutive days, cull it from the rabbitries as it usually is a rier of P. multocida and is able herd. If you are not sure whether postmortem diagnosis. Broad‑ to infect offspring and caged to cull a rabbit, “when in doubt, spectrum antibiotics have been ­neighbors. cull it out.” used with some degree of success Fluoroquinolones (e.g., Bay‑ In addition to a strict culling with pet and show rabbits. tril) may be used in individual program, good ventilation must Pyometra be provided to control snuffles. rabbits. Antibiotic combina‑ “Pyometra” means pus in the tions have been used to reduce There is a direct correlation between the level of ammonia uterus. The walls of the uterus symptoms in pet rabbits with usually are dilated, and the organ some success. Antimicrobial in a rabbitry and the amount of respiratory disease. An effective is filled with pus. Affected manure removal system and females will not produce and, 10–20 air changes per hour are therefore, are culled and often necessary to reduce the ammonia slaughtered. Pyometra results to an acceptable level. from the introduction of Pasteu- rella bacteria into the uterus dur‑ Pneumonia ing mating and may be traced Upper respiratory disease to a single buck with a chronic (snuffles) may spread to the infection of the testicles. It also lungs and cause pneumonia. can occur as a retrograde infec‑ Rabbit mortality surveys reveal tion from the vagina. pneumonia to be present in Does that are nasal‑positive 25 percent of the animals exam‑ for P. multocida often are vaginal- ined; it is the greatest single positive for the same bacteria, cause of death in mature ani‑ Figure 3.—Gross appearance of especially if the doe has a nasal rabbit lungs, showing consolidation mals. Signs of pneumonia are discharge. The vagina is thought depression, labored breathing, due to Pasteurella bacteria. to be contaminated during the

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normal practice of coprophagy Enteritis (eating their own feces; see “Enteritis” is a group designa‑ page 29) or during the kindling tion much like “pasteurellosis.” (birth) process. Any diarrheal‑type disease that Treatment of pyometra sel‑ kills rabbits generally is placed dom is attempted because the in this grouping. In the past, the disease usually is not noticed group designation often has been until the female is slaughtered. called “enteritis complex,” as Successful treatment is unlikely. many different symptoms were Pets sometimes can be saved by observed, but the one unifying an ovariohysterectomy. factor was death as the final Orchitis Figure 4.—Wryneck resulting from a result of the syndrome. More middle and inner ear infection. recently, specific diseases have Orchitis is an infection of the been described; they are dis‑ testicles. The testicle becomes Although the Pasteurella organ‑ cussed below. enlarged and usually contains an ism is sensitive to certain antibi‑ abscess. Pus can be seen when otics, treatment generally is not Enterotoxemia the testicle is cut open. Some‑ effective because of the isolated Enterotoxemia is an explo‑ times infection is limited to the location of the infection. sive diarrheal disease of young membranes covering the penis, a Subcutaneous abscesses rabbits 4–8 weeks of age. Rab‑ condition called balanoposthitis. Pasteurella may cause abscesses bits often are observed to be Balanoposthitis appears as a in many organs, but abscesses are normal one day and dead the reddening and swelling of the especially evident when they next with or without evidence membrane covering the penis, occur in the subcutaneous tissue. of diarrhea. This acute death is and a white exudate (pus) is These appear as soft swellings due to a deadly toxin produced present on these membranes. As under the skin. Treatment con‑ by the bacteria Clostridium spi- described above, the infection is sists of opening and draining the roforme. Young rabbits die in transmitted to does by infected abscess and administration of 24–48 hours; occasionally adult bucks during breeding. systemic antibiotics. and junior breeders are affected, Treatment seldom is and they may live as long as attempted; however, balanopos- Septicemia 96 hours. Penicillin used to treat thitis may be treated by applying This form of pasteurello‑ rabbits may also cause the disease antibiotic ointment containing sis usually is an overwhelm‑ by altering the gut bacteria. penicillin or other suitable anti‑ ing blood stream infection of The typical lesions of entero‑ biotics to the penis. short duration without clinical toxemia seen at necropsy are a signs, resulting in death. Tis‑ Otitis media fluid‑filled intestine that is cov‑ sue changes are limited to a few ered with petechial hemorrhages. Middle ear infection of one or hemorrhagic areas on the heart The hemorrhage is most apt to both ears causes filling of the and pericardium, swelling of the be observed in the cecum. The tympanic cavity with a purulent spleen, and slight congestion of causative agent, C. spiroforme, exudate. If the process spreads to the upper digestive tract. The can be isolated on blood agar, the inner ear, the equilibrium of lack of clinical signs and short but it is an anaerobic bacte‑ the animal is disturbed, and head duration do not allow time for rium and must be grown under tilt or wryneck results (Figure 4). suitable treatment. anaerobic conditions. Diagnosis

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Mucoid enteropathy feed seems to increase water This uncommon enteric dis‑ consumption and decrease the ease affects rabbits of any age incidence of the disease. Add‑ and is a chronic type of diarrhea ing salt to the drinking water or constipation. Rabbits live or salt spools in the cage is not for several days and sometimes ­beneficial. several weeks with this disease. Tyzzer’s disease However, they will not eat and Tyzzer’s disease was first they sit hunched in the cage and described in Japanese waltzing Figure 5.—This rabbit has mucoid grind their teeth as if in pain. mice, but since has been found enteropathy. Note feces on hind feet, They sometimes look bloated in a variety of animals, including rough fur coat, hunched posture, and and often are crouched near the (uncommonly) rabbits. Clos- squinty eyes. water supply (Figure 5). tridium piliformes is the causative The etiology of this disease is organism. of this disease is accomplished by unknown, but one common Signs of the acute form seen demonstrating the iota‑like toxin finding in almost all cases is in weanling animals are diarrhea, in the intestinal contents or by constipation. Impaction of the listlessness, lack of appetite, and staining and microscopic exami‑ cecum and/or terminal part of dehydration, followed by death nation for the distinctive bacteria the small intestine is observed at within 72 hours. Lesions include in centrifuged cecal content. A necropsy in about 75 percent of edema, hemorrhage, and necro‑ mouse bioassay test or an intra- the cases. Along with the finding sis in the wall of the cecum and dermal test in guinea pig skin of a gelatinous‑type of mucus focal necrosis in the liver and commonly is used to detect the in the colon, this leads to the heart (Figure 6). The organisms toxin. diagnosis of mucoid enteropathy. are found in cells near necrotic Little is known about the Other lesions observed during areas, and the demonstration of transmission of the organism, a postmortem examination are typical bacteria within the cell is but it has been shown that rab‑ generalized dehydration and essential to diagnosis. Animals bits do not have this organism as excess water in the stomach. This part of their normal microflora. latter finding causes a “splash” or The type of diet seems to be a “water bottle” sound when these factor in the development of the animals are rocked to and fro disease. Diets high in fiber close to one’s ear. reduce the incidence of the The impaction often can be disease. The addition of hay or palpated through the abdominal straw to a low‑fiber diet is ben‑ wall on young fryer rabbits, but eficial. Antibiotics used in the treatment is not very successful. feed or water give temporary By the time the disease is recog‑ remission of symptoms, but the nized, the rabbit seldom can be disease recurs once they are saved. Rehydration with electro‑ lytes sometimes is beneficial. The Figure 6.—Tyzzer’s disease. This rabbit removed unless the diet has been died acutely with diarrhea. At autopsy, changed. addition of excess salt to the focal areas of cell death (arrows) were ration occasionally helps stop seen in the liver. Photograph courtesy of an outbreak. Salt added to the Academic Press and Co., New York.

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surviving the acute stage might In septicemia, death can occur Necrobacillosis live to adulthood but fail to grow suddenly without previous ill‑ at a normal rate. ness. Generally the rabbit is Fusobacterium necrophorum, depressed, weak, has a nasal an anaerobic bacterium in Transmission of Tyzzer’s dis‑ farm animals, is considered a ease is by direct contact with discharge, and may have con‑ vulsions. Nervous system signs ­secondary invader rather than a fecal-contaminated feed and primary cause of disease. bedding. Some form of stress, include incoordination, loss of such as overcrowding or equilibrium, and rolling move‑ Lesions first appear on the extremes in temperature, is nec‑ ments. These signs may persist lower lip, which becomes swol‑ essary for initiating the condi‑ for several days or weeks, and len, purplish, and painful to the tion in nature. complete recovery is rare. Sick touch. Later, small abscesses are pregnant animals have a puru‑ seen that contain a thick, puru‑ Antibiotics reduce the effect lent material. These abscesses of the disease in mice, but drugs lent metritis, lose weight, and may abort. Survivors generally are enclosed in a tough, fibrous seem to be of little value in rab‑ capsule, with little tendency to bits. The best alternative is pre‑ are useless for breeding because of uterine damage and pyometra rupture and drain. The disease vention through strict sanitation, progresses to ulceration and especially daily thorough (pus within the uterus). The most consistent lesion at necrosis of the skin and subcu‑ removal of fecal material from taneous tissues in the face, head, the cage floor. Because this seems necropsy is liver necrosis. The lesions consist of a few pinpoint and neck. When the liver and to be a highly transmissible dis‑ lungs become involved, the ani‑ ease, the only way to treat severe foci to almost complete stud‑ ding of the liver. The mesenteric mal becomes emaciated and dies outbreaks is to depopulate and after several weeks. repopulate with disease‑free lymph nodes may be enlarged ­rabbits. and reddened. In cases of metri‑ Inadequate sanitation in the tis, the uterine wall is thickened, rabbitry, especially dirty cages, Coccidiosis the mucous membrane may be is prerequisite to this disease. Coccidiosis is one of the covered with a grayish exudate, When scratches, bite wounds, or enteric diseases. The etiologic and the fetuses are decomposed skin wounds become contami‑ agents are protozoan parasites or mummified. When infected nated with feces containing the that attack the liver or intestines. fetuses are retained in the uterus, etiologic agent, necrobacillosis This disease is discussed under severe metritis develops. is most likely to occur. The bac‑ “Internal parasites,” page 21. Due to their tolerance by rab‑ teria are sensitive to exposure to bits and their specific mode of aerobic conditions and will not Listeriosis action, antibiotics of the tetra‑ live long when exposed to air cycline group are the best drugs (oxygen). Listeria monocytogenes causes for treating listeriosis. In treat‑ When the disease is recog‑ a rare septicemic infection in ing pregnant rabbits, antibiotics nized and treated in its early young rabbits, a meningo‑ probably will not prevent fetal stages, recovery is usual; when encephalitis in adults, and metri‑ death, and females saved by there is extensive ulceration tis and fetal mortality in preg‑ antibiotics may be sterile as a and abscessation, death ensues. nant does. Pregnant females and result of the infection. The most The organism is sensitive to does that recently have delivered effective prevention of losses is some antibiotics, including young are most susceptible. immediate isolation of diseased ­metronidazole. The organisms are ingested or pregnant animals. inhaled.

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gram‑negative bacteria. In organisms in their feces long rabbits, the disease is char‑ after treatment. Pigeons, spar‑ acterized by septicemia and rows, and wild rodents have rapid death, with diarrhea and been shown to be reservoirs of ­abortion commonly observed. Salmonella. Protect stored feed When outbreaks occur, they and bedding from these possible often are explosive, with high carriers. morbidity and mortality. Mortal‑ ity is highest in young rabbits Staphylococcosis and pregnant does. Bacteria are shed in the feces of carrier rab‑ Staphylococcus aureus causes bits and clinically ill animals. septicemic infections and abscesses in numerous organs, ➔ Infection usually takes place by the oral route, and signs including the subcutaneous tis‑ appear after 3–6 days. The first sue, lungs, kidneys, and heart. ➔ signs are listlessness, ruffled hair This organism is known espe‑ ➔ ➔ coat, loss of appetite, and cially for causing infection in diarrhea. Later, the respiration the mammary glands of nursing rate increases, and body temper‑ does. The breasts become swol‑ ature may rise. In its acute form, len, hot, and may become blu‑ the disease progresses rapidly to ish, accounting for the alternate death. In the chronic form, there name “blue‑breast.” may be no signs of illness other Cutaneous lesions in young Figure 7.—Cutaneous abscesses on than a transient diarrhea. animals appear as small abscesses young rabbit caused by Staphylo- The most prominent lesions and later develop into firm case‑ coccus. found at necropsy are in the ous nodules (Figure 7). These liver, spleen, mesenteric lymph abscesses usually are found on Salmonellosis nodes, lungs, and intestine. the lower abdomen, on the inner Naturally occurring Salmo- Hemorrhagic and ulcerative aspects of the forelegs, and on nella infections are uncommon changes are present in the intes‑ the lower jaw. Small, white nod‑ in domestic rabbits. Salmonella tine. The liver and spleen usually ules also may be found in the organisms are spread easily by are enlarged and contain pin‑ lungs and heart. The Staphylo- fecal contamination, and a single point, pale areas of necrosis. The coccus organism also may cause infected animal can quickly lymph nodes may be soft, hem‑ bronchopneumonia. The lungs infect a whole colony. Rabbits orrhagic, and enlarged. Surviving are consolidated, with numer‑ also can become infected by rabbits become carriers and may ous necrotic lesions. The bron‑ human caretakers, as Salmonella shed bacteria in their feces inter‑ chi and trachea may contain a bacteria occur in humans as well. mittently for a long time. mucopurulent exudate. Salmonellosis in rabbits gen‑ Streptomycin and other anti‑ Bacteria enter the skin erally is caused by Salmonella biotics have been used effectively through broken or abraded areas typhimurium or S. enteritidis, against Salmonella. Animals following birth; transmission but S. pullorum also has been treated with chlortetracycline occurs from mother to young. isolated. All members of the respond to the medication, but Staphylococci live in the nasal salmonellae group are aerobic, may continue to excrete passages of rabbits, and the close

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contact associated with kindling is so rapid that few if any lesions ­surrounding tissues, flushing the and nursing offers opportunities are observed. Occasionally, small, eye with sterile saline or boric for both direct contact and aero‑ superficial pustules or abscesses acid solution, and applying an sol transmission. (Figure 7) are seen on the skin of ­ophthalmic ointment containing Mastitis results from inva‑ dead kits or littermates. Diagno‑ an antibiotic. sion of the milk glands by the sis usually depends on isolating Conjunctivitis sometimes disease‑producing bacteria. The S. aureus from the heart blood. becomes a chronic problem in glands and teats become red The organism generally enters show rabbits, where the lacrimal and swollen and may advance to the young kit from ingested milk secretions cause a loss of fur at blue‑black tissues, which are from mammary glands, or it may the medial canthus of the eye. warm to the touch. The doe enter the body through abrasions This condition sometimes is alle‑ may refuse to nurse her young or scratch wounds that become viated by intravenous antibiotic and generally loses her appetite. contaminated with S. aureus. administration or by repeatedly Young from does with mastitis Staphylococci might be sen‑ flushing the lacrimal duct with should not be fostered to other sitive to several medications; an antibiotic solution. This nursing does because the disease however, some strains of the procedure is best done with the might be transmitted to the fos‑ organism are resistant to one or rabbit under anesthesia and with ter doe. Mastitis also may result more of these drugs. Laboratory a small-gauge cannula inserted from abrasions to the teats or tests may be necessary to deter‑ into the opening of the delicate insufficient removal of milk mine which drugs should be and tortuous lacrimal duct found when too few young are left with used. Consult a veterinarian for on the lower eyelid near the the doe or when the young are current recommendations. medial canthus. weaned too soon. Mastitis The septicemic form of staph‑ Mastitis most commonly Treponematosis ylococcosis results in peracute is caused by Staphylococcus (vent disease) death in young rabbits, primarily aureus; it is discussed under Treponematosis, sometimes those still in the nest box. Death “Staphylococcosis,” page 12. called “vent disease,” spirochet‑ Conjunctivitis (weepy eye) osis, or rabbit syphilis, is caused by Treponema cuniculi. Other Conjunctivitis is a common members of the genus include malady of young rabbits raised T. pallidum, the cause of human under crowded conditions. syphilis. Some of the early work Mature does and bucks occasion‑ on human syphilis was done ally are affected. Red, swollen with rabbits. After finding that eyes with a copious exudate are rabbits had a natural spiro‑ characteristic of this disease. In chete, T. cuniculi, the validity young rabbits, the eyelids often of this early work in rabbits was are stuck shut (Figure 8). It may ­questionable. affect only one eye or both. The bacteria most often isolated are There is a great deal of confu‑ Staphylococcus aureus and Pasteu- sion concerning the incidence of rella multocida. Conjunctivitis treponematosis in rabbits. is treated by opening the eye‑ Recent reports indicate it is Figure 8.—Conjunctivitis (weepy eye) lids, if stuck shut, cleaning the much more common in com‑ caused by Staphylococcus infection. mercial rabbitries than previously

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believed. In fact, serological tests Spirochetes also are found in with pathogenic bacteria and have demonstrated antibodies to regional lymph nodes, and becomes very sore. Antibiotic T. cuniculi in a high percentage they seem to survive in this tis‑ salves and ointments hasten heal‑ of adult rabbits despite the sue much longer than on the ing, but cleaning and drying the absence of observed lesions. skin surface. Old lesions heal floors are essential to prevent Transmission of the organism ­completely without scarring, but ­recurrence. originally was believed to be by recovered rabbits are susceptible sexual contact, and this method to later infection. Pseudotuberculosis still is thought to be primary; The spread of spirochetosis Pseudotuberculosis is an however, vertical transmission can be prevented by examining uncommon disease, but some‑ from mother to offspring has the genitals of both sexes before times occurs in rabbitries with been demonstrated. Vertical mating and by eliminating rab‑ substandard sanitation. The transmission accounts for bits with lesions. The organism causative agent is a bacterium, the rabbits 6–8 weeks of is sensitive to arsenicals and Yersinia pseudotuberculosis. age that show evidence of penicillin. Three subcutaneous Granulomatous nodules resem‑ treponematosis. injections of benzathene peni‑ bling tuberculosis are observed Lesions of treponematosis cillin G-procaine penicillin G at necropsy throughout the may resemble those of injury, (42,000 IU/kilogram of body intestine and occasionally in the fungal infection, or ectoparasites. weight) are necessary to eradi‑ parenchyma of the liver, lungs, A correct diagnosis is important cate treponematosis from a rab‑ or spleen. The organism, which because the disease is transmitted bit herd. Injections are given at seems to thrive in filthy condi‑ primarily by breeding, and an weekly intervals, and rabbits all tions, enters the host through isolated case can lead to an out‑ must be treated, regardless of the contaminated food or water. break among the breeding stock. presence or absence of lesions. The disease is a chronic, debili‑ Exchange of infected bucks may Penicillin, however, may cause tating condition with signs of spread the infection among fatal enterotoxemias in some poor appetite, depression, slowly colonies. ­rabbits. developing emaciation, and The first signs usually are eventual death. small blisters around the external Hutch burn Treatment of this disease sex organs. Lesions involving the Hutch burn often is confused seldom is effective. Prevention nose, mouth, and ears also occur with rabbit syphilis. It is difficult can be accomplished by good in both sexes. The lesions are to differentiate the two diseases sanitation procedures, including irregular in shape, tan‑brown, without the use of a dark‑field disinfecting cages, nest boxes, and either edematous or dry microscope. With this micro‑ and ancillary equipment. This and scaly. Sometimes weeping, scope, the spirochetes of trepo‑ disease has been diagnosed in coalescing vesicles are found. nematosis are seen easily. Hutch humans and other animals; Facial and other lesions usu‑ burn affects the membranes therefore, affected rabbits should ally are secondary and the result of the anus and genital region. be destroyed and not marketed. of reinfection by contact with They become very red and genital‑anal lesions when the chapped. The major cause is Tularemia animal cleans itself. All lesions wet and dirty cage floors that show many spirochetes by spe‑ come in contact with these Tularemia, sometimes called cial microscopic (dark‑field) membranes. The area soon rabbit fever or deer fly fever, is an ­examination. becomes secondarily infected infectious disease of wild animals and humans that is caused by

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Francisella tularensis. Tularemia Sierra Nevada Mountains, and can be carried by many wild the tip of the peninsula of Baja and domestic animals, certain California. birds, deer flies, and ticks. It is Transmission of the disease an important malady of wild by mosquitoes led to the name rabbits, but not of domestic “mosquito disease.” Myxoma‑ ranch‑raised rabbits. tosis also is referred to as “big Infected wild rabbits move head disease” because of edema sluggishly and are visibly sick. around the eyes, ears, lips, Yellow or white spots on the liver and nose in the early stages of or spleen are common lesions. ­infection. Figure 9.—This animal, affected with Diagnosis is made by bacterial Clinical signs include lus‑ myxomatosis, shows heavy, pendulous cultures of suspect lesions. terless eyes with a purulent ears and matted eyes. Domestic rabbits are susceptible discharge and elevated body to infection with this organism temperature. Edema of the ears Microscopic tissue examina‑ under laboratory conditions, but causes them to become heavy tion or virus isolation is required the disease has not been reported and pendulous (Figure 9). As the for a definite diagnosis of myxo‑ to occur naturally in commercial disease progresses, edema of the matosis. Large eosinophilic rabbitries. Tularemia might be head and anogenital region and a cytoplasmic inclusion bodies in transmitted from rabbit tissues nasal discharge occur; death the conjunctival membranes are to humans. follows in 10–12 days. In sur‑ observed microscopically. This vivors, widespread subcutane‑ finding, along with appropri‑ ous gelatinous tumors develop ate clinical signs, is evidence of Viral diseases all over the body, including the myxomatosis. Myxomatosis ­eyelids. The virus is spread by direct The myxoma virus was iso‑ Occasionally, acute outbreaks contact and by biting insects lated first in South America of myxomatosis occur and rab‑ such as mosquitoes and fleas, from diseased laboratory rabbits; bits die in 24–48 hours. About which act as mechanical vectors. the virus later was found to be the only clinical signs observed Control consists of prompt iden‑ a widespread natural infection are a slight redness in the con‑ tification of the disease, destruc‑ in wild cottontail rabbits. In junctival membranes and an tion of infected animals, and wild brush rabbits (Sylvilagus increased body temperature reduction of mosquito popula‑ bachmani), it causes only mild (about 108°F). tions by draining or spraying tumors, which regress after sev‑ Rabbits dying from myxo‑ breeding areas. Screen enclosure eral weeks; the disease is fatal matosis exhibit no characteristic of the entire rabbitry is an effec‑ only in the very young. In con‑ gross visual changes by which tive but costly solution. Antibi‑ trast, the disease can completely the infection can be diagnosed otics are not effective in treating wipe out some susceptible popu‑ definitely. Usually, there is con‑ sick animals. An attenuated lations of domestic rabbits. gestion and consolidation of the vaccine is used for preventing Confirmed cases of myxoma‑ lungs, and the spleen is enlarged, myxomatosis in Europe, but the tosis follow the geographical dis‑ dark red, and pulpy. The cut sur‑ vaccine is not approved for use tribution of the California brush face of each edematous subcuta‑ in the United States. The only rabbit, which is limited by the neous tissue is white, gelatinous, effective measures available for Pacific Ocean, the Columbia and glistening; when pressed, use in California and Oregon are River in Oregon, the Cascade‑ clear fluid exudes. test and slaughter. Check rectal

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temperature of suspect rabbits on the other hand, develop Another herpes virus that may and immediately kill sick rabbits small, subcutaneous nodules to be responsible for producing with a temperature greater than diffuse indurations involving lymphoid tumors in cottontail 104°F. Bury or burn the car‑ muscle and tendon. The exter‑ rabbits recently has been isolated casses. This method, along with nal genitalia become red and from these rabbits. ­implementing a control program ­swollen. Death is frequent in for flying insects, has been suc‑ unweaned young. Rabbit papilloma cessful in stopping several major The cut surfaces of the nod‑ outbreaks in large rabbitries. Rabbit papilloma virus has ules are pale and glistening and been identified as the causative may have radiating white streaks. agent of wartlike growth on the Rabbit pox In young animals, the tumors skin of cottontail rabbits are more widely spread over the This rare disease can occur (Figure 10). Domestic rabbits with or without manifestation body and often coalesce. There and jackrabbits are susceptible to of clinical disease. In either case, may be involvement of the kid‑ experimental infection. The virus the lesions include lymphadeni‑ neys, liver, intestinal tract, bone can be recovered from lesions on tis, papular nodules on the marrow, and mesentery. cottontail rabbits, but not from mucous membranes, and orchi‑ The role of mosquitoes and papillomas on domestic rabbits. tis. Mortality is highest among other insects as vectors of rabbit Naturally occurring papilloma‑ the unweaned young and may fibroma virus has been estab‑ tosis has been found in domestic reach 75 percent. Rabbit pox lished. Given the proper envi‑ rabbits in southern California, virus rarely is a cause of epizoot‑ ronment (such as an epizootic in but the virus produces no evi‑ ics, but usually is very serious wild cottontail rabbits) and an dence of a generalized illness. adequate mosquito population, when it does occur. Vaccination The most common sites for this viral disease could result with vaccinia virus confers papillomas are the ears and eye‑ in significant economic loss of immunity. lids, and the growths vary in size young domestic rabbits. and conformity. The growths are Fibroma well keratinized, and the upper Rabbit fibroma virus was Herpes virus infection surfaces are irregular and often isolated from nodules beneath Virus III or Herpesvirus cunic- split. The lower portions of the the skin of wild cottontail rab‑ uli of rabbits exists as a latent growth are pinkish and fleshy to bits. These viral fibromas (firm infection in some stock lines of the touch. As the warts become growths) were transmitted to domestic rabbits. The virus does older, they increase in size, domestic rabbits. It once was not produce a natural disease, become more cornified, and are believed that fibroma virus nor are other species of animals hard to the touch. At this stage, infected only wild cottontail rab‑ susceptible. A virus with char‑ they are easily scratched off by bits; however, an outbreak has acteristics of the herpes group the rabbit or knocked off when been reported in a commercial has been recovered from rabbits handled. Papillomas removed rabbitry. with respiratory signs. Its role in this way leave a free‑bleeding as a pathogen has not been elu‑ surface, which heals without In the cottontail rabbit, complications. fibroma virus causes a benign cidated, but its association with tumor that regresses within a few respiratory disease may be Rabbit papilloma virus prob‑ weeks. Young domestic rabbits, important. ably is spread by free‑flying insects such as mosquitoes; there

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is no virus multiplication in insect tissue. Transmission of the virus from lesions of cottontail rabbits to domestic rabbits is most likely.

Oral papilloma Wartlike growths in the mouth, especially on the lower surface of the tongue, are caused by a virus (one of the papovaviruses) different from the rabbit papilloma virus. Sev‑ eral spontaneous outbreaks of this disease have occurred, all in New York and Massachusetts. The growths on the tongue usually regress without specific ­treatment.

Viral enteric diseases During the past decade, sev‑ eral viruses have been isolated from rabbits with diarrhea. Figure 10.—Rabbit papilloma. Scaly growths on the ear were caused by Rotovirus, coronavirus, and papilloma virus. adenovirus all have been incrimi‑ nated in enteritis outbreaks. The Viral hemorrhagic the body organs such as the clinical signs and pathology of disease lungs, liver, heart, spleen, and the viral enteric diseases are very mucous membranes. The liver is Viral hemorrhagic disease similar to those described under extremely swollen and brownish (VHD) first was reported in the section on bacterial diseases. red. It is not clear whether viruses China in 1984. Since then, it has occurred in many European rab‑ Although the disease is very act as the primary agent (with rare in the United States, ani‑ pathogenic bacteria as secondary bit-raising countries, in Mexico, and in the United States. Rab‑ mal health authorities keep a invaders) or whether natural out‑ vigilant eye on imported rabbits breaks of enteritis can be caused bits with the disease show inco‑ ordination, convulsions, and and rabbit meat. The disease has by these viral entities alone. A escaped from quarantine centers great deal of work currently is evidence of severe pain. There usually is a bloody nasal dis‑ in Australia and New Zealand being done to answer the ques‑ and is decimating wild Oryctol‑ tions of viral pathogenicity and charge. Mortality rate of affected animals is very high. lagus rabbit populations in those immunology. countries. Postmortem examination reveals hemorrhages throughout

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Fungal diseases ­yellow, dry crusts (Figure 11). culture. Examination under The hairs may be broken close Wood’s (ultraviolet) light may Two main groups of fungi, to the skin surface and become indicate Microsporum but not Trichophyton and Microsporum, matted. The name “ringworm” is Trichophyton.­ are found on rabbits and pro‑ suggested by the circular lesion Infection of young rabbits duce disease of the skin and that often develops from the fur under certain conditions. probably occurs in the nest box. outward growth of the fungi. The nest‑box material becomes Not only can rabbits serve as Lesions usually are found on reservoirs for human infection, contaminated with fungus the nose, ears, eyelids, and feet. from the adult, and minor skin but humans can transmit their Their size varies, and in severe ­fungus infection to rabbits. ­abrasions allow the fungus cases whole areas of the body to become established on the Because they produce a similar may be involved. The infection disease known as ringworm, young. When nursing, the young usually is most severe in nurs‑ are in direct contact with skin the two organisms are discussed ing young; single small lesions together in this section. and fur around the doe’s teats, are more likely found in adults. and the fungus is easily trans‑ Fungus infections cause Diagnosis of fungus infection ferred to the mouth and nose patchy areas of hair loss and depends on finding fungi in regions of the infants. These thickened skin covered with skin and hair scrapings and by same fungal organisms are found on dogs, cats, domestic livestock, and wild rodents around farm buildings. Fungal infections must be dif‑ ferentiated from other types of skin problems, such as mite infestations, hair pulling, fight wounds, molting, and vitamin deficiencies. If ringworm is sus‑ pected after an evaluation of the lesions and clinical history, a skin scraping should be performed. The scraping should be taken from the periphery of the lesions, treated with 10 percent potassium hydroxide, and exam‑ ined under a light microscope with reduced illumination. Fun‑ gal forms are identified easily by trained personnel. When small numbers of ani‑ mals are involved, a topical antifungal medication may be applied directly to affected areas. Figure 11.—Ringworm infection showing loss of fur and scaling of skin on the In larger outbreaks, an oral or ears (arrow).

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systemic medication is preferred. Prevention and control rabbits rarely are infested with Griseofulvin, an antifungal drug, Prevention of parasite infec‑ parasites in significant numbers. is the medication of choice. Each tion is far cheaper and preferable Modern pens are constructed so animal should receive 12 mil‑ to treatment. The best preventive that they can be kept clean and ligrams (mg) per pound of measures are sanitation, good free from the infective forms body weight per day for at least housing, adequate food ration, of parasites. Proper cleaning of 15 days. Dissolve the drug in and an understanding of poten‑ cages and use of good disinfec‑ water and administer to the rab‑ tial parasite problems. Where tants, together with a good diet, bit by gastric intubation. During good husbandry is the rule, are the keys to parasite control. treatment, add a fungicidal dust such as sulfur to the nest‑box material. Griseofulvin can be added to the feed at the rate of 370 mg per pound of feed and fed to all rabbits in the herd for a period of 2 weeks. While this is an extremely effective and easy way to treat ringworm, it presents a problem: The drug has never been cleared for use in rabbit feed in the United States and, therefore, cannot be added to the feed by a commercial feed com‑ pany. This situation may be resolved in the near future.

Parasitic diseases Rabbits are susceptible to a number of parasites, but only a few are of economic importance. The problems caused by all of these parasites are greatly influ‑ enced by methods of feeding, handling, and housing. If these are satisfactory, and if recently acquired animals are quaran‑ tined for a few days and checked for disease, most economically important parasitisms can be avoided. Figure 12.—Treating ear mites with a cotton swab soaked in medicated oil.

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External parasites Place oil-based preparations (two examined microscopically for or three drops) in both ears of all evidence of mites and eggs. To Ear mites adult and potential replacement treat fur mites in a few rabbits, Psoroptes cuniculi, the com‑ rabbits in the herd. Massaging apply a cat flea powder at weekly mon ear mite of rabbits, causes the base of the ear after adminis‑ intervals for several treatments. ear mange or canker. This condi‑ tering the medication distributes If a fur mite infestation becomes tion is a very common parasitic the drug throughout the sur‑ a herd problem, treat with injec‑ disease in commercial rabbitries. face of the ear canal. If rabbits tions of ivermectin or dip rabbits The mites live in the ear canal are severely infected and have (wear gloves) in a 0.5 percent and damage the skin lining this a large amount of debris in the malathion solution at 10‑day area. An exudate of brown, waxy ear canal, soften the debris with intervals for two treatments. material soon covers the inner mineral oil and remove it with Cuterebrid flies ear (Figure 12). This dark cotton-tipped applicators and encrustation consists of cellular tweezers before drug application. Larvae of Cuterebra flies are debris, keratin, dried blood, Treat rabbits with noticeable ear common subcutaneous parasites and mites in varying stages of mite infestations every day for of wild rabbits but infrequent ­development. three treatments, every other parasites of domestic rabbits. day for three treatments, and The adult fly appears wherever The complete life cycle of the populations of wild rabbits exist. mite takes less than 3 weeks, and then weekly for three treatments. Treat rabbits without notice‑ Rabbits are infected when the fly a severely infested ear can con‑ deposits eggs on the fur. Grub tain as many as 10,000 mites. In able ear mites monthly for three treatments. Ivermectin is given worms hatch from these eggs severe cases, the entire inner and burrow into the skin to form surface of the pinna may be two or three times at 2-week intervals. warbles. The larvae grow under involved, as well as the side of the skin and may get as long as the head, the neck, and even Fur mites three‑quarters of an inch the chin and shoulders. Severely Cheyletiella parasitovorax and ( Figure 13). When full-grown, affected rabbits lose flesh, fail to Listrophus gibbus are two com‑ the grubs leave the skin, drop reproduce, and succumb to sec‑ mon mites inhabiting the skin to the ground, and develop into ondary infections. of rabbits. In healthy, well‑fed adult flies. The warbles cause Treatment of ear mite infesta‑ rabbits these mites seldom cause tions requires a plan and perse‑ a problem and rarely are noticed. verance. If ear mites are detected If a rabbit becomes sick or is in one rabbit, they likely are in underfed, alopecia, sores, or others in the herd also. To rid the scabs may develop in the neck herd of this bothersome para‑ or dorsal trunk areas. Intense site, treat all rabbits in the herd itching may occur, which causes regardless of whether ear mites constant scratching with the are detected. Treating just the hind legs and the consequent one rabbit will result in continu‑ loss of hair and injury to the ally treating one or two rabbits a skin. week. Diagnosis of fur mites is best Most mineral‑oil‑based ear accomplished by scraping the mite medications containing a skin of the affected area with a Figure 13.—Cuterebra larva. An parasiticide are effective, as are scalpel blade dipped in mineral eraser on a pencil is shown for size treatments using ivermectin. oil. The resulting debris then is comparison.

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little trouble when they are larvae then form pupae from parasite of wild rabbits, but found in small numbers. The which adult fleas emerge. rarely is found on domestic rab‑ larvae can be removed by enlarg‑ Control is aimed at killing the bits because their housing is not ing the opening in the skin and adults on the host and the compatible with the life cycle of drawing them out gently with immature forms in the nest box. the tick; however, this tick is one tweezers. Paint the wound with To destroy adult fleas, dust rab‑ of the reservoirs of tularemia, an antiseptic. bits with a commercial prepara‑ a serious human disease. Take Fleas and ticks tion of pyrethrum or rotenone. care to ensure that wild rabbits Rabbits are not commonly Repeat several times during a are not allowed access to areas in infested with fleas; however, the 2‑week period. Control imma‑ which domestic rabbits are being raised. rabbit flea,Spilopsyllus cuniculi, ture forms by burning old and the dog and cat fleas,Cteno- nest‑box litter and scrubbing cephalides canis and C. felis, occa‑ nest boxes with hot water and Internal parasites sionally have been reported on household bleach. More modern rabbits. There are four stages in drugs for preventing and treat‑ Coccidiosis the life cycle of these fleas—egg, ing ectoparasitism in dogs and Coccidiosis is a prevalent larva, pupa, and adult. The eggs cats may be used in rabbits also. parasitic disease of domestic rab‑ are deposited on bedding and in Consult a veterinarian. bits. It is caused by a microscopic cracks of nest boxes and develop The rabbit tick, Haemaphysa- protozoal parasite that invades into larvae in a short time. These lis leporispalustris, is a common the intestine or liver. In these locations, the parasite multiplies extensively and then sheds eggs in the feces. At least four species or types of coccidia live in the intestine, and one species grows in the liver. Not all species of coccidia are equally harmful, and rabbits tolerate moderate numbers of some without displaying illness. The most dangerous of the intes‑ tinal forms are Eimeria magna, E. media, E. perforans, and E. irresidua. These produce diar‑ rhea, poor appetite, weight loss, and sometimes death. E. irre- sidua evokes the most severe tissue damage. In some cases, patches of epithelium die and slough away from the intestinal wall. The diagnosis of coccidiosis depends on the finding of the oocysts (eggs) in the feces or Figure 14.—Life cycle of coccidia. intestinal contents. However,

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experience is needed to judge whether sufficient numbers of parasites are present to account for the disease signs, because other disorders may produce similar signs. Control of intestinal coccid‑ iosis depends largely on manage‑ ment practices that minimize the danger of fecal contamination of feed, water, and hutch floors. Wire‑bottom floors greatly Figure 15.—Livers of rabbits affected with hepatic coccidiosis. reduce the hazard presented by solid floors or slots. However, treatment is not suggested unless Liver coccidiosis is acquired brush wire floors daily with a clinical disease appears. Meat in the same manner as intes‑ wire brush to ensure that fecal rabbits so treated must be held tinal coccidiosis. The control material falls through the wires. for at least 10 days following ­measures also are similar; how‑ This breaks the life cycle of the cessation of treatment to allow ever, liver coccidiosis can be organism. Design feeders so that breakdown of antimicrobial resi‑ controlled more easily by proper fecal contamination is held to a due in muscle tissue. management. When the disease minimum. An automatic water Eimeria stiedae, the one spe‑ does occur, feed containing system is recommended. Oocysts cies that multiplies in the liver, is 0.025 percent sulfaquinoxaline is passed out in the feces require considered to be the most patho‑ an effective treatment. It can be moisture and warmth to sporu‑ genic coccidium of rabbits. Like fed at this level for 3 weeks; use late and become infective the other forms, it enters the it only until management con‑ (Figure 14). Dry wire floors and intestinal wall, but it migrates trol measures can be introduced. automatic water systems hin‑ to the bile ducts, where it repro‑ der sporulation of the parasite. Encephalitozoonosis duces. Infections lasting more Oocytes persist in the environ‑ Encephalitozoon cuniculi (a than 16 days can be recognized ment and are difficult to kill protozoan parasite) is the cause by white circular nodules on the with most common sanitizing of a mild but long-standing dis‑ liver (Figure 15). The parasite agents. ease in rabbits. The condition multiplies in the epithelial cells was first described as a chronic Treatment has only a tempo‑ of the bile ducts, which become rary effect during the early stages encephalitis, sometimes with thickened and tortuous and con‑ clinical signs such as a spontane‑ of intestinal coccidiosis, but it tain a vast number of oocysts. may be useful in controlling ous paralytic disease. A chronic In the early stages of infection, nephritis caused by the parasite outbreaks. When indicated, a there are no unusual symp‑ ration containing 0.025 percent was overlooked for many years, toms. Then appetite decreases, but current studies indicate that sulfaquinoxaline may be fed for a potbelly develops, and death 2 to 3 weeks to reduce the num‑ many apparently healthy ani‑ sometimes follows. In moderate mals have kidney lesions related bers of parasites to a level where infections, there is no mortality, control can be accomplished by to this infection. These lesions but disfigurement of the liver vary from cortical scarring proper management. Intestinal makes it unmarketable; hence coccidia develop a tolerance to with multiple small, indented, this type of coccidiosis always is gray areas on the surface to the drug if used continuously, so of economic significance.

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a granulomatous nephritis also in screening rabbits to point At necropsy, the lesions of this (Figure 16). The scars extend out possible carriers or infected disease vary. In the acute form, from the cortical surface to the ­animals. there is extensive necrosis of the medulla. Toxoplasmosis lymph nodes, liver, spleen, and Encephalitozoonosis is a con‑ lungs. This generally is observed Toxoplasmosis is an uncom‑ histologically, but grossly the tagious, colony infection. The mon protozoal disease of rabbits organisms are passed in the urine organs may be swollen, and caused by Toxoplasma gondii. necrotic small white foci may be and transmitted when there is The disease has been reported urinary contamination of feed observed. The parasitic organ‑ worldwide in both domestic ism often is found with the aid or water. A diseased doe also can and wild rabbits. The disease transmit the disease to unborn of a microscope in these necrotic probably is more common than foci. In the chronic form, there rabbits in the uterus. The disease reported, as antibody tests on can be controlled by providing may be microscopic lesions but rabbit herds have shown that no apparent gross lesions, and good sanitation and preventing as many as 50 percent of clini‑ contamination of food and organisms often are confined to cally normal rabbits have been the central nervous system. water by urine. No treatment is exposed. available. Diagnosis of toxoplasmosis There are two forms of the Diagnosis of encephalito- generally is accomplished at disease. In the acute form, the necropsy by observation of his‑ ­zoonosis in a rabbit herd is rabbit develops anorexia, fever, difficult. It usually is done at tologic lesions and organisms. lethargy, and (in a few days) cen‑ necropsy by observing histo‑ Various serological tests also tral nervous symptoms ranging pathologic lesions typical of the might be useful. Treatment in from ataxia or posterior paraly‑ disease. Recently, several diag‑ most cases is not practical, and sis to generalized convulsions. nostic tests have been developed the emphasis should be on pre‑ Death usually occurs about a that will help with the diagnosis vention. Cats, the primary week after symptoms are first in live rabbits. An carrier of this organism, should Encephalito- noted. In the chronic form, infection can be detected by be kept out of rabbitries or at zoon the disease occurs over a much an indirect fluorescent antibody least away from feed storage longer period of time. In fact, it test, a skin test, or by a carbon areas. Take precautions to ensure may be latent, with onset stimu‑ immunoassay utilizing India that feed and water are not con‑ lated by stress. With the chronic ink. These tests may be helpful taminated with toxoplasma form, either no symptoms are in antemortem diagnosis and oocysts. observed or there is a progressive emaciation that might end in Roundworms posterior paralysis and death. Only one roundworm pres‑ Transmission of the disease ents a problem in domestic may occur in two ways. Cats can rabbits. Several more have been shed the parasite in their stool reported in wild rabbits, but and thereby contaminate stored these rarely occur in domestic rabbit feed; then the contami‑ rabbits. The pinworm, Passalurus nated feed is ingested by rabbits. ambiguus, is a very common The parasite also can be trans‑ parasite of domestic rabbits, but mitted through the placenta of a it does not affect other animals Figure 16.—Halves of kidneys from two or people. rabbits showing pitting of the surface pregnant doe to her offspring. caused by Encephalitozoon cuniculi (right).

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These pinworms are glisten‑ 1 ing white, and ⁄2 inch long. They often are seen on the surface of freshly passed feces or through the wall of the cecum when rab‑ bits are slaughtered. Ordinarily, pinworms do little harm. As the mature worms become inactive, they are passed out of the cecum as fecal pellets are formed. These parasites are spread from ani‑ mal to animal by ingesting feed and water contaminated by the droppings of infected animals. Management methods used to control coccidiosis are effective against pinworms. When treat‑ ment is necessary, piperazine citrate is effective when admin‑ istered at 100 mg/100 milliliters (ml) drinking water for 1 day. Reinfection occurs readily. Figure 18.—Life cycle of the dog tapewarm. Tapeworms Tapeworms occur in rabbits The rabbit tapeworm Cit- tapeworm segments and eggs as adults in the intestine and as totaenia variablis is uncommon from the feces of dogs. larval forms in the liver and in domestic rabbits. It is flat, The young larvae then are abdominal cavity. The ribbon‑shaped, and made up released from the eggs, penetrate adult forms are very rare in of numerous segments. It has the digestive tract, and migrate hutch‑raised rabbits, but larval a head with four suckers with to the liver. They migrate within forms occasionally are observed. which the worm attaches to the the liver, leaving white streaks lining of the intestine. Rabbits behind, then leave the liver and harboring a few tapeworms show enter the abdominal cavity. They no signs of the disease. When form small, fluid‑filled cysts (cys‑ many tapeworms are present, ticerci), which may be attached diarrhea and emaciation might to the membranes holding the occur. Control is readily intestinal tract or may exist free accomplished by good in the abdominal cavity ­sanitation. (Figure 17). Each cyst contains The larval forms of tapeworm an embryonic tapeworm that, most often found are those of when consumed by a dog, will Figure 17.—Rabbit liver with several Taenia pisiformis. They are found develop into a mature tapeworm. cysticerci attached (arrow). in the abdominal cavity and in By excluding dogs from the the liver. Rabbits acquire these rabbitry, transmission of tape‑ tapeworms by ingesting contam‑ worm eggs can be prevented inated feed and water containing (Figure 18). Dogs kept on

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premises where rabbits are raised ­containing glucose may reverse ­gestation period. When maternal should not be allowed to eat the breakdown of body fats blood levels fall below 20 micro‑ any part of a raw rabbit carcass. and halt production of ketones. grams (ug) per 100 ml serum, Treatment for larval stages in the Junior does should not be too fat hydrocephalus appears in a large rabbit is not practical, so con‑ when bred for the first litter. percentage of the young. Com‑ trol must be accomplished by mercial diets, in general, supply ­management. Vitamin A deficiency adequate levels of vitamin A; however, the vitamin does dete‑ Low‑grade vitamin A defi‑ riorate after prolonged storage of Nutritional ciency adversely affects the alfalfa hay. reproductive performance of t has been shown by workers diseases females, often before other signs I at Oregon State University’s Rab‑ are noted. Premature degenera‑ Pregnancy toxemia bit Research Center that tion of the ovum and reduced Also known as “ketosis,” this of vitamin A can numbers of fertilized ova result. excess levels disease is a toxemia of pregnancy cause the same signs and symp‑ Resorption of the fetus or abor‑ that is most common in first­ toms as of the vitamin. tion during late gestation also is deficiency litter females. Signs of ketosis are Low fertility, abortions, resorp‑ noted. dullness of the eyes, sluggishness, tion, and hydrocephalus were respiratory distress, prostration, Rabbits born to females fed a seen in does given excessive vita‑ and death after 1 to 4 days. The diet deficient in vitamin A may min A in the diet. Excess vitamin disease occurs in the last week be hydrocephalic at birth. A may be a problem if a vitamin of pregnancy and is much more Hydrocephalus, or “water on premix is added to rabbit diets prevalent in obese animals. The the brain,” is characterized by containing high levels of alfalfa. probable major cause is starva‑ distention of the portion of the tion with subsequent metabolic skull that covers the brain. Cases effects on the doe and young. may not be apparent because Vitamin E deficiency For some reason, there is a loss of the young die soon after birth or Infant mortality, character‑ appetite and failure to eat. This are born dead. Animals that live ized by death of entire litters may be the result of minor diges‑ show signs of nervous system at 3 to 10 days of age without tive upset (hairballs in the stom‑ involvement. Wryneck, loss of clinical signs prior to death, has ach are common), an abrupt equilibrium, and incoordination been associated with vitamin E reduction in exercise, or a ration persist for several days or weeks. deficiency. Affected infants do containing too little digestible Impaired coordination may pre‑ not reveal any gross lesions of carbohydrate. When carbohy‑ vent animals from eating, and diagnostic significance. Produc‑ drate energy declines, body fat is eventually they die of starva‑ ing females become less fertile mobilized for energy, and ketone tion. Enlargement of the head as the deficiency progresses. bodies are produced and enter is caused by increased pressure The problem can be treated the bloodstream. The liver within the brain. On cut section, because adequate supplementa‑ becomes fatty and appears brown the ventricles (cavities) of the tion of vitamin E will stop infant and soft. brain are greatly enlarged and ­mortality and correct infertility. filled with a clear, colorless fluid. Alfalfa hay is a suitable source of Birth of the litter or abortion vitamin E in commercial rations, is apt to be curative if either Hydrocephalus is caused and 8–9 mg/100 grams (g) feed occurs shortly after the onset by low maternal blood levels is adequate. of signs. Injections of fluids of vitamin A throughout the

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problems in rabbit colonies. The misalignment, which also results dental formula of the rabbit is: in malocclusion. This type of incisors 2/1, canines 0/0, premo‑ malocclusion is difficult to dif‑ lars 3/2, and molars 3/3. Con‑ ferentiate from inherited maloc‑ stant chewing and gnawing keep clusion. Therefore, the best the teeth ground down to proper solution is to regard all maloc‑ length and size. When the lower clusion as inherited. The reces‑ jaw is shorter or longer than the sive malocclusion genes can be upper jaw or teeth are damaged, eliminated from a breeding herd malocclusion of the incisors by selective breeding. Figure 19.—Malocclusion. might result in overgrowth (Figure 19). The cheek teeth Hereditary (premolars and molars) meet and Splay leg and ataxia diseases grind evenly in normal animals. Splay leg in rabbits is due to These teeth continue to grow one or more recessive genetic Glaucoma and depend on constant grind‑ factors. The condition might ing against opposing teeth to be similar to the hip dysplasia Glaucoma (buphthalmia) found in certain breeds of dogs. occurs in both laboratory and maintain their shape. If there is commercial rabbit colonies. This a malposition of the jaw, broken The disease is characterized condition is of interest to oph‑ teeth, or malformation, over‑ by an inability to put weight on thalmologists because of its simi‑ growth will occur in the cheek one or both hind legs, and might larity to congenital glaucoma in teeth similar to that which even involve all four limbs. The humans, and rabbits may serve occurs in the incisors. limbs are twisted so the animals as a useful animal model. Signs of malocclusion are have a double-jointed posture. gradual loss of appetite and Affected animals are not para‑ Glaucoma appears first as a lyzed. They eat normally, seem light bluish cloudiness on the weight. Both sides of the mouth may become stained with saliva. to be well, and move by wrig‑ cornea. One or both eyes may be gling along on their belly and affected. Progressive opacity fol‑ Animals become progressively listless, dehydrated, and unable chest. The pathologic effects are lows, and protrusion of the eye‑ limited to the hip and shoulder. ball becomes noticeable. Corneal to chew properly. Complications opacity may lead to blindness. are abscessed teeth, growth of Ataxia (muscle incoordina‑ teeth into the upper jaw, and tion) resembles splay leg in some Glaucoma probably is the death from starvation. respects. It is, however, a lethal result of an abnormal drainage recessive genetic factor. The dis‑ mechanism and the inability to Malocclusion of the incisors can be corrected temporarily ease usually appears when the maintain normal fluid relation‑ animal is 2 to 3 months of age ships in the eye. It is a semilethal by cutting back the teeth so the animals can eat and attain good and runs its course in 30 days. In defect that is transmitted as a ataxia, the nervous system is recessive trait. condition before slaughter. However, never use these ani‑ involved, and at first the animal mals as breeding stock because might not be able to use its hind Malocclusion many types of malocclusion are legs effectively. Later the animal Malocclusion and tooth over‑ inherited. Young rabbits occa‑ cannot move, and its body tem‑ growth, or “wolf teeth,” have sionally pull on cage wires or perature drops below normal long been recognized as common feeders with their teeth and cause until death ensues.

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Miscellaneous Draining water lines or crocks distended. Paralyzed animals and refilling with cold water for have a displaced or slipped verte‑ Cannibalism immediate consumption aid in bra. Malposition of the vertebra Most cases of cannibalism reducing rabbits’ body tempera‑ compresses and damages the spi‑ are the result of a diet that is ture. It is also helpful to change nal cord with resulting paralysis. inadequate in either quality or breeding schedules to reduce Injury to the vertebra may be quantity, injury or abnormality the number of late‑pregnancy caused by improper handling, in a baby rabbit, or disturbance does in the hottest part of the use of a tattoo box too short for of the doe following kindling. ­summer. the animal, or injury. Many inju‑ Proper feeding and seclusion ries occur at night when predator at kindling usually prevent the Broken back animals invade the rabbitry. In tendency. A valuable doe that an effort to evade the predator destroys her first litter should be This condition is character‑ and protect the young, the adult given another chance. If she con‑ ized by sudden paralysis with no “stamps” firmly with its hind tinues to kill young, she should apparent cause. Paralysis extends feet. As a result, a vertebra be culled from the breeding posterior from the middle of becomes displaced, and the spi‑ population. the back and may be complete nal cord is damaged. or partial (paresis). The animal dult rabbits have been moves with its front legs and A observed to cause a luxation Heat prostration drags the hindquarters. The uri‑ of the vertebrae by sudden Heat prostration results from nary bladder may become greatly prolonged exposure to excessive heat. Losses may be high in females due to kindle or in baby rabbits if nest boxes are poorly ventilated. Just before dying, ani‑ mals breathe rapidly and become comatose. Provide relief to adult animals suffering from the heat by spray‑ ing them with water or placing a wet burlap feed sack on the cage floor for them to rest on. Remove some bedding and fur from nest boxes to improve cir‑ culation of air around kits. In locations subject to high temperatures, overhead water sprinklers help to reduce the air’s temperature by evaporation. Aluminum‑roofed sheds reflect the heat, and burlap sacks soaked in water can be hung from the edges of the roofs to shade and cool the air. Figure 20.—Sore hocks.

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­movements when startled by animal seldom is useful as a Fur eating and a person entering the rabbitry. breeder. The best method of ­hairballs This is especially true if back‑ treatment is prevention. Preven‑ Several rabbits in a hutch ground noise (such as a radio) is tion is accomplished in three may eat body fur, eyelashes, and not available and the person is a ways. First, cull all affected whiskers. Single rabbits eat fur stranger. breeders from the breeding herd on their sides, back, and rump. because of a genetic predilection If a rabbit is completely The cause generally is a defi‑ for sore hocks (thickness of the paralyzed, it generally is killed. ciency of dietary fiber and gastric foot pad). Second, clean cage However, some success has been atony. Diets high in cereal grains floors daily and never allow observed in does with paresis and low in alfalfa often have a manure to hang on cage floors. (some motor function or sensory low fiber content. Because the Third, inspect cage floors capability) by putting the rabbit rabbit’s digestive system is frequently for rough spots or in a small cage for 30 to 60 days. designed for handling large rusty areas. The smaller cage limits the rab‑ amounts of fiber, a deficiency in bit’s activity and allows time for the diet causes the animal to seek repair of the injury. Tumors another source of fiber, and hair Spontaneous tumors in rabbits chewing begins. Increasing fiber Sore hocks rarely are reported because the in the diet almost always elimi‑ Sore hocks are inflamed bare animals are slaughtered before nates the problem. Overcrowd‑ spots, devoid of fur, found on they reach the age at which ing in a cage also can cause hair the bottom surface of the hind tumors are most apt to occur. loss, mainly from fighting. legs (Figure 20). In severely With the increasing use of Rabbits also eat small amounts affected cases, secondary infec‑ rabbits as laboratory animals, of hair by licking or grooming tions with Staphylococcus occur. interest in these growths can be themselves. The hair may accu‑ Both front and hind feet might expected. Tumors have been mulate in the stomach and form become involved. As the hocks observed in the uterus, kidneys, hairballs. These usually cause no of the hind feet become painful, blood, lymph nodes, bones, disease, but they may obstruct the animal throws more weight testicles, skin, and other organs. the stomach. When obstruction to the front feet, adding stress to Adenocarcinomas of the uteri are occurs, the rabbit quits eating, the front feet and causing them not uncommon in does over loses weight, and may die. to become affected. Wet, dirty 2 years of age. Usually they are If a hairball is suspected, hutch floors and the irritating multiple and occur in both uteri. parenteral fluids, gastric muscle action of urine salts are predis‑ Most cases of lymphosarcoma stimulation, massage of the posing factors. The breed also (tumors of cells from lymph (delicate) stomach, and, perhaps, is a factor in the development nodes) occur in mature females. administration of 10 ml of pine‑ of sore hocks; the disease is seen Neoplastic cells are found in apple juice by stomach tube or more often in large breeds than numerous body organs, but the medicine dropper 3 days in a in smaller breeds. Rex rabbits are most outstanding lesions are row might help. An enzyme in prone to the disease because of in the kidneys. Another tumor the juice might help break up thin foot pads. originates from embryonic the hairball and allow it to pass Treatment of sore hocks often cells in the kidneys (embryonal through the digestive system. is nonproductive. Even if treat‑ nephroma) and is observed with Surgery might be needed in ment is successful, the lesion some frequency in domestic some cases. almost always returns, and the ­rabbits.

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Coprophagy yellow fat. Plant pigments also How to pack and Rabbits take soft fecal pellets affect urine color from the vent and swallow them ship specimens intact. This is a natural physi‑ Winter breeding for laboratory ological process for rabbits and ­depression diagnosis should not be misinterpreted A very common occurrence in as a nutritional condition or The best way to obtain an rabbitries in cold climates is a accurate diagnosis is to take dead depraved appetite. Coprophagy decrease in productivity during is practiced at night by tame rab‑ animals or two or three sick ani‑ the winter. The syndrome usu‑ mals showing typical signs to the bits and during the day by wild ally has these common elements: rabbits in their burrows. Fermen‑ nearest animal diagnostic labora‑ small litters, abortions, weak tory and supply any additional tation of the feces in the large litters that can’t nurse, does that intestine supplies an abundance information the pathologist may don’t have enough milk, and need. If delivery in person is not of certain B vitamins to the fecal does that will not breed. All of pellets, probably improves the convenient, the dead animals can these factors lead to a decreased be shipped. quality of the protein in the soft number of fryers toward the end pellets, and improves fiber break‑ of the winter. Although many down by bacterial action. By per‑ causes for this syndrome have Shipping dead animals mitting a second passage of food been postulated, the basic prob‑ If you cannot take your rab‑ through the digestive tract, the lem is inadequate nutrition. bits to a diagnostic laboratory rabbit gains additional nutritive because of distance, the next best value from the food. Breeding does (and sometimes bucks) require more energy in thing is to send the dead rabbits cold weather to keep warm. If to the laboratory. Yellow fat you use a restricted feeding pro‑ Because it is against postal reg‑ Yellow body fat is an inher‑ gram (rabbits are not fed all they ulations to send frozen carcasses ited condition in rabbits. It is want), increase the amount of of diseased animals through the included here only to prevent feed in cold weather. Otherwise, mail, shipment must be made by misunderstanding or association the doe will not have enough bus or air express. United Parcel with a disease condition (jaun‑ food calories to provide body Service will not accept carcasses. dice). Yellow fat is a genetic heat and energy for the repro‑ Label the outside of the box trait determined by a recessive duction process. Reproduction “Biological specimen,” “Rush,” gene. Alfalfa and other green will be suspended until adequate and “Keep in a cool place.” feeds contain xanthophyll, a nutrition is available, which usu‑ If the carcass is to be shipped fat‑soluble compound that is yel‑ ally occurs as warmer weather a short distance, chill (but never low in color. Animals with the arrives. freeze) it thoroughly and place yellow fat gene lack an enzyme The treatment for this syn‑ it in the center of a box contain‑ that reduces (changes) the xan‑ drome is either to increase ing sawdust or shavings. For thophyll pigment to a colorless ­gradually the amount of feed long-distance shipments, place product. Therefore, the xantho‑ (usually to about double) or to dry ice around the carcass, then phyll is deposited in the body increase the amount of energy pack it as indicated above. Never fat, making it yellow. White fat in the diet by increasing the put dry ice in an airtight jar or in meat rabbits is preferred to amount of carbohydrate or fat. can. If the gas cannot escape, it may cause an explosion. Properly

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used, dry ice will prevent spoil‑ age for 2 or 3 days. Use pesticides safely! Many specimens decompose When you use any pesticide, observe these rules: after arriving at the laboratory because no one is available to • Wear protective clothing and safety devices as recom‑ take care of them promptly. mended on the label. Bathe or shower after each use. With this in mind, do not send • Read the pesticide label—even if you’ve used the pesticide fresh specimens that will arrive before. Follow closely the instructions on the label (and any on a weekend; most laboratories other directions you have). do not operate on Saturday or • Be cautious when you apply pesticides. Know your legal Sunday. Address the package to responsibility as a pesticide applicator. You may be liable for the laboratory itself, not to an injury or damage resulting from pesticide use. individual employee. This will ensure more immediate atten‑ tion. Do not send carcasses that have started to decompose. It • Dates of first losses and subse‑ is better to kill an animal or quent losses two that show typical signs, or • Incidence of infection to ship them alive if there is a (whether it is in just one chance they may reach their des‑ house or pen, or scattered tination before death. throughout the rabbitry) • What treatment, if any, has Accompanying been given information • Type and brand of feed and Letters that do not contain feeding methods used for the sufficient information are a prob‑ past 6 months lem to the pathologist. In some • Type of housing (whether the diseases, a complete history is rabbits are kept on wire or more useful than the carcass. The solid floors) accompanying letter should con‑ • Any other information tain the following information: that might help explain the • Number of rabbits on the ­outbreak ranch It is best to telephone the lab‑ • Number of sick or dead oratory so the staff can be alerted ­animals to the arrival of the specimen. If • Age and sex of affected they need further information, ­animals they can ask at that time. • Description of the disease as you observed it. For example, “Rabbits develop watery diar‑ rhea, quit eating and drinking, and die in 1 or 2 days.”

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© 2008 Oregon State University Pacific Northwest Extension publications are jointly produced by the three Pacific Northwest states—Oregon,W ash- ington, and Idaho. Similar crops, climate, and topography create a natural geographic unit that crosses state lines. Since 1949 the PNW program has published more than 500 titles. Joint writing, editing, and production have prevented duplication of effort, broadened the availability of faculty specialists, and substantially reduced the costs for participating states. Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the Oregon State University Extension Service, Washington State University Cooperative Extension, the University of Idaho Cooperative Extension System, and the U.S. Department of Agriculture cooperating. The three participating Extension Services offer educational programs, activities, and materials—without regard to age, color, disability, gender identity or expression, marital status, national origin, race, religion, sex, sexual orientation, or veteran’s status—as required by Title VI of the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972, and Section 504 of the Rehabilitation Act of 1973. The Oregon State University Extension Service, Washington State University Cooperative Extension, and the University of Idaho Cooperative Extension System are Equal Opportunity Employers. Published September 1986. Revised January 2008.