- Rabbits are subject to a wide variety of diseases that cause death or decrease the quality of life for survivors. Most diseases can be avoided through good breeding and management practices. A healthy animal is alert and active and has a good, smooth coat. Its droppings are round and firm. Daily observation of the animals will allow you to note the first signs of disease. Remove and isolate the sick animals from the rest of your rabbits.
- “Pasteurellosis” is the designation for all diseases associated with Pasteurella multocida. The disease manifestations are varied and include rhinitis (snuffles), pneumonia, pyometra, orchitis, otitis media, conjunctivitis, subcutaneous abscesses, and septicemia.
- 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 characterized by nasal sounds and by a catarrhal (mucus or pus) nasal discharge. The extent to which the infection spreads into the lower respiratory passages 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 discharge. The inner aspects of the rabbit’s forepaws may be caked with exudate because of attempts to wipe the exudate away from the nose.
- Pasteurella bacteria often are found in the nasal sinuses of healthy looking rabbits. Stress resulting from extremes of temperature, high humidity, high ammonia levels, travel, pregnancy, and lactation is a primary factor in the development of snuffles.
- Treatment of snuffles has not proven to be economically effective in commercial rabbitries. By using broad spectrum antibiotics such as oxytetracycline or chlortetracycline, the symptoms might be alleviated. However, the animal often remains a carrier of P. multocida and is able to infect offspring and caged neighbors.
- Fluoroquinolones (e.g., Baytril) may be used in individual rabbits. Antibiotic combinations have been used to reduce symptoms in pet rabbits with some success. Antimicrobial residues might remain in the treated rabbits’ meat for days or weeks, making the meat unusable for human consumption. Penicillin use may cause fatal enterotoxemias.
- If the nasal discharge regresses, take care not to stress the rabbit. It should not be used as a breeder. The next stress period (e.g., kindling, lactation, heat wave) very likely will cause the symptoms to reappear. Vaccines have not proven to be effective. The only effective method of control is strict culling. If a rabbit has a nasal discharge or matted paws or sneezes on 2 consecutive days, cull it from the herd. If you are not sure whether to cull a rabbit, “when in doubt, cull it out.”
- In addition to a strict culling program, good ventilation must be provided to control snuffles. There is a direct correlation between the level of ammonia in a rabbitry and the amount of respiratory disease. An effective manure removal system and 10–20 air changes per hour are necessary to reduce the ammonia to an acceptable level.
- Upper respiratory disease (snuffles) may spread to the lungs and cause pneumonia. Rabbit mortality surveys reveal pneumonia to be present in 25 percent of the animals examined; it is the greatest single cause of death in mature animals. Signs of pneumonia are depression, labored breathing, bluish eye color in albinos, and a nasal discharge. The body temperature usually is above normal.
- Gross lesions of the lungs appear as red consolidated areas, sunken purple areas, and abscesses. The consolidated lesions most often are in the anterior lobes of the lungs (Figure 3). A catarrhal exudate is found in the air passages. Abscesses appear with thin, fibrous capsules close to the surface of the lungs. Sometimes there are adhesions between the wall of the chest cavity and the lungs.
- Pneumonia rarely is treated in rabbitries as it usually is a postmortem diagnosis. Broad spectrum antibiotics have been used with some degree of success with pet and show rabbits.
Otitis Media (Wry Neck)
- Middle ear infection of one or both ears causes filling of the tympanic cavity with a purulent exudate. If the process spreads to the inner ear, the equilibrium of the animal is disturbed, and head tilt or wryneck results. Although the Pasteurella organism is sensitive to certain antibiotics, treatment generally is not effective because of the isolated location of the infection.
- This form of pasteurellosis usually is an overwhelming blood stream infection of short duration without clinical signs, resulting in death. Tissue changes are limited to a few hemorrhagic areas on the heart and pericardium, swelling of the spleen, and slight congestion of the upper digestive tract. The lack of clinical signs and short duration do not allow time for suitable treatment.
- “Enteritis” is a group designation much like “pasteurellosis.” Any diarrheal type disease that kills rabbits generally is placed in this grouping. In the past, the group designation often has been called “enteritis complex,” as many different symptoms were observed, but the one unifying factor was death as the final result of the syndrome. More recently, specific diseases have been described; they are discussed below.
- Enterotoxemia is an explosive diarrheal disease of young rabbits 4–8 weeks of age. Rabbits often are observed to be normal one day and dead the next with or without evidence of diarrhea. This acute death is due to a deadly toxin produced by the bacteria Clostridium spiroforme. Young rabbits die in 24–48 hours; occasionally adult and junior breeders are affected,and they may live as long as 96 hours. Penicillin used to treat rabbits may also cause the disease by altering the gut bacteria.
- The typical lesions of enterotoxemia seen at necropsy are a fluid-filled intestine that is covered with petechial hemorrhages.The hemorrhage is most apt to be observed in the cecum. The causative agent, C. spiroforme, can be isolated on blood agar, but it is an anaerobic bacterium and must be grown under anaerobic conditions. Diagnosis of this disease is accomplished by demonstrating the iota like toxin in the intestinal contents or by staining and microscopic examination for the distinctive bacteria in centrifuged cecal content. A mouse bio assay test or an intradermal test in guinea pig skin commonly is used to detect the toxin.
- Little is known about the transmission of the organism, but it has been shown that rabbits do not have this organism as part of their normal microflora. The type of diet seems to be a factor in the development of the disease. Diets high in fiber reduce the incidence of the disease. The addition of hay or straw to a low-fiber diet is beneficial. Antibiotics used in the feed or water give temporary remission of symptoms, but the disease recurs once they are removed unless the diet has been changed.
- This uncommon enteric disease affects rabbits of any age and is a chronic type of diarrhea or constipation. Rabbits live for several days and sometimes several weeks with this disease. However, they will not eat and they sit hunched in the cage and grind their teeth as if in pain.They sometimes look bloated and often are crouched near the water supply (Figure 5).
- The etiology of this disease is unknown, but one common finding in almost all cases is constipation. Impaction of the cecum and/or terminal part of the small intestine is observed at necropsy in about 75 percent of the cases. Along with the finding of a gelatinous-type of mucus in the colon, this leads to the diagnosis of mucoid enteropathy. Other lesions observed during a postmortem examination are generalized dehydration and excess water in the stomach. This latter finding causes a “splash” or“water bottle” sound when these animals are rocked to and fro close to one’s ear.
- The impaction often can be palpated through the abdominal wall on young fryer rabbits, but treatment is not very successful. By the time the disease is recognized, the rabbit seldom can be saved. Rehydration with electrolytes sometimes is beneficial. The addition of excess salt to the ration occasionally helps stop an outbreak. Salt added to the feed seems to increase water consumption and decrease the incidence of the disease. Adding salt to the drinking water or salt spools in the cage is not beneficial.
- Staphylococcus aureus causes septicemic infections and abscesses in numerous organs, including the subcutaneous tissue, lungs, kidneys, and heart. This organism is known especially for causing infection in the mammary glands of nursing does. The breasts become swollen, hot, and may become bluish, accounting for the alternate name “blue-breast.”
- Cutaneous lesions in young animals appear as small abscesses and later develop into firm caseous nodules (Figure 7). These abscesses usually are found on the lower abdomen, on the inner aspects of the forelegs, and on the lower jaw. Small, white nodules also may be found in the lungs and heart. The Staphylococcus organism also may cause bronchopneumonia. The lungs are consolidated, with numerous necrotic lesions. The bronchi and trachea may contain a mucopurulent exudate.
- Bacteria enter the skin through broken or abraded areas following birth; transmission occurs from mother to young. Staphylococci live in the nasal passages of rabbits, and the close contact associated with kindling and nursing offers opportunities for both direct contact and aerosol transmission.
- Mastitis results from invasion of the milk glands by the disease-producing bacteria. The glands and teats become red and swollen and may advance to blue-black tissues, which are warm to the touch. The doe may refuse to nurse her young and generally loses her appetite. Young from does with mastitis should not be fostered to other nursing does because the disease might be transmitted to the foster doe. Mastitis also may result from abrasions to the teats or insufficient removal of milk when too few young are left with the doe or when the young are weaned too soon.
- The septicemic form of staphylococcosis results in peracute death in young rabbits, primarily those still in the nest box. Death is so rapid that few if any lesions are observed. Occasionally, small, superficial pustules or abscesses (Figure 7) are seen on the skin of dead kits or littermates. Diagnosis usually depends on isolating S. aureus from the heart blood. The organism generally enters the young kit from ingested milk from mammary glands, or it may enter the body through abrasions or scratch wounds that become contaminated with S. aureus.
- Staphylococci might be sensitive to several medications; however, some strains of the organism are resistant to one or more of these drugs. Laboratory tests may be necessary to determine which drugs should be used. Consult a veterinarian for current recommendations.
Conjunctivitis (Weepy Eye)
- Conjunctivitis is a common malady of young rabbits raised under crowded conditions. Mature does and bucks occasionally are affected. Red, swollen eyes with a copious exudate are characteristic of this disease. In young rabbits, the eyelids often are stuck shut (Figure 8). It may affect only one eye or both. The bacteria most often isolated are Staphylococcus aureus and Pasteurella multocida. Conjunctivitis is treated by opening the eyelids, if stuck shut, cleaning the surrounding tissues, flushing the eye with sterile saline or boric acid solution, and applying an ophthalmic ointment containing an antibiotic.
- Conjunctivitis sometimes becomes a chronic problem in show rabbits, where the lacrimal secretions cause a loss of fur at the medial canthus of the eye. This condition sometimes is alleviated by intravenous antibiotic administration or by repeatedly flushing the lacrimal duct with an antibiotic solution. This procedure is best done with the rabbit under anesthesia and with a small-gauge cannula inserted into the opening of the delicate and tortuous lacrimal duct found on the lower eyelid near the medial canthus.
Viral Enteric Diseases
- During the past decade, several viruses have been isolated from rabbits with diarrhea. Rotovirus, coronavirus, and adenovirus all have been incriminated in enteritis outbreaks. The clinical signs and pathology of the viral enteric diseases are very similar to those described under the section on bacterial diseases. It is not clear whether viruses act as the primary agent (with pathogenic bacteria as secondary invaders) or whether natural outbreaks of enteritis can be caused by these viral entities alone. A great deal of work currently is being done to answer the questions of viral pathogenicity and immunology.
- ERE differs from other intestinal diseases known rabbits by clinical and lesion specific table. Besides diarrhea and mortality, there is generally a pronounced abdominal bloating due to expansion of all segments of the digestive tract including the stomach whose contents are highly liquid. These symptoms are sometimes associated with cecal paresis and the presence of mucus, especially in the colon and sometimes in the small intestine.
More Info on Epizootic Rabbit Enteropathy (ERE)
- Two main groups of fungi, Trichophyton and Microsporum, are found on rabbits and produce disease of the skin and fur under certain conditions. Not only can rabbits serve as reservoirs for human infection, but humans can transmit their fungus infection to rabbits. Because they produce a similar disease known as ringworm, the two organisms are discussed together in this section.
- Fungus infections cause patchy areas of hair loss and thickened skin covered with yellow, dry crusts (Figure 11). The hairs may be broken close to the skin surface and become matted. The name “ringworm” is suggested by the circular lesion that often develops from the outward growth of the fungi. Lesions usually are found on the nose, ears, eyelids, and feet. Their size varies, and in severe cases whole areas of the body may be involved. The infection usually is most severe in nursing young; single small lesions are more likely found in adults. Diagnosis of fungus infection depends on finding fungi in skin and hair scrapings and by culture. Examination under Wood’s (ultraviolet) light may indicate Microsporum but not Trichophyton.
- Infection of young rabbits probably occurs in the nest box. The nest-box material becomes contaminated with fungus from the adult, and minor skin abrasions allow the fungus to become established on the young. When nursing, the young are in direct contact with skin and fur around the doe’s teats, and the fungus is easily transferred to the mouth and nose regions of the infants. These same fungal organisms are found on dogs, cats, domestic livestock, and wild rodents around farm buildings.
- Fungal infections must be differentiated from other types of skin problems, such as mite infestations, hair pulling, fight wounds, molting, and vitamin deficiencies. If ringworm is suspected 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 examined under a light microscope with reduced illumination. Fungal forms are identified easily by trained personnel.
- When small numbers of animals are involved, a topical antifungal medication may be applied directly to affected areas. systemic medication is preferred. Griseofulvin, an antifungal drug, is the medication of choice. Each animal should receive 12 milligrams (mg) per pound of body weight per day for at least 15 days. Dissolve the drug in water and administer to the rabbit by gastric intubation. During 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 company. This situation may be resolved in the near future.
- 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 influenced by methods of feeding, handling, and housing. If these are satisfactory, and if recently acquired animals are quarantined for a few days and checked for disease, most economically important parasitisms can be avoided.
- Prevention and Control
- Prevention of parasite infection is far cheaper and preferable to treatment. The best preventive measures are sanitation, good housing, adequate food ration, and an understanding of potential parasite problems. Where good husbandry is the rule, rabbits rarely are infested with parasites in significant numbers. Modern pens are constructed so that they can be kept clean and free from the infective forms of parasites. Proper cleaning of cages and use of good disinfectants, together with a good diet, are the keys to parasite control.
- Psoroptes cuniculi, the common ear mite of rabbits, causes ear mange or canker. This condition is a very common parasitic disease in commercial rabbitries.
- The mites live in the ear canal and damage the skin lining this area. An exudate of brown, waxy material soon covers the inner ear (Figure 12). This dark encrustation consists of cellular debris, keratin, dried blood, and mites in varying stages of development.
- The complete life cycle of the mite takes less than 3 weeks, and a severely infested ear can contain as many as 10,000 mites. In severe cases, the entire inner surface of the pinna may be involved, as well as the side of the head, the neck, and even the chin and shoulders. Severely affected rabbits lose flesh, fail to reproduce, and succumb to secondary infections.
- Treatment of ear mite infestations requires a plan and perseverance. If ear mites are detected in one rabbit, they likely are in others in the herd also. To rid the herd of this bothersome parasite, treat all rabbits in the herd regardless of whether ear mites are detected. Treating just the one rabbit will result in continually treating one or two rabbits a week.
- Most mineral-oil-based ear mite medications containing a parasiticide are effective, as are treatments using ivermectin. Place oil-based preparations (two or three drops) in both ears of all adult and potential replacement rabbits in the herd. Massaging the base of the ear after administering the medication distributes the drug throughout the surface of the ear canal. If rabbits are severely infected and have a large amount of debris in the ear canal, soften the debris with mineral oil and remove it with cotton-tipped applicators and tweezers before drug application. Treat rabbits with noticeable ear mite infestations every day for three treatments, every other day for three treatments, and then weekly for three treatments. Treat rabbits without noticeable ear mites monthly for three treatments. Ivermectin is given two or three times at 2-week intervals.
- Pet-Informed #Rabbit Ear Mites
- Cheyletiella parasitovorax and Listrophus gibbus are two common mites inhabiting the skin of rabbits. In healthy, well-fed rabbits these mites seldom cause a problem and rarely are noticed. If a rabbit becomes sick or is underfed, alopecia, sores, or scabs may develop in the neck or dorsal trunk areas. Intense itching may occur, which causes constant scratching with the hind legs and the consequent loss of hair and injury to the skin.
- Diagnosis of fur mites is best accomplished by scraping the skin of the affected area with a scalpel blade dipped in mineral oil. The resulting debris then is examined microscopically for evidence of mites and eggs. To treat fur mites in a few rabbits, apply a cat flea powder at weekly intervals for several treatments. If a fur mite infestation becomes a herd problem, treat with injections of ivermectin or dip rabbits (wear gloves) in a 0.5 percent malathion solution at 10-day intervals for two treatments.
- Coccidiosis is a prevalent parasitic disease of domestic rabbits. It is caused by a microscopic protozoal parasite that invades 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 intestinal forms are Eimeria magna, E. media, E. perforans, and E. irresidua. These produce diarrhea, poor appetite, weight loss, and sometimes death. E. irresidua 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 intestinal contents. However, 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 coccidiosis depends largely on management practices that minimize the danger of fecal contamination of feed, water, and hutch floors. Wire-bottom floors greatly reduce the hazard presented by solid floors or slots. However, brush wire floors daily with a wire brush to ensure that fecal material falls through the wires. This breaks the life cycle of the organism. Design feeders so that fecal contamination is held to a minimum. An automatic water system is recommended. Oocysts passed out in the feces require moisture and warmth to sporulate and become infective (Figure 14). Dry wire floors and automatic water systems hinder sporulation of the parasite. Oocytes persist in the environment and are difficult to kill with most common sanitizing agents.
- Treatment has only a temporary effect during the early stages of intestinal coccidiosis, but it may be useful in controlling outbreaks. When indicated, a ration containing 0.025 percent sulfaquinoxaline may be fed for 2 to 3 weeks to reduce the numbers of parasites to a level where control can be accomplished by proper management. Intestinal coccidia develop a tolerance to the drug if used continuously, so treatment is not suggested unless clinical disease appears. Meat rabbits so treated must be held for at least 10 days following cessation of treatment to allow breakdown of antimicrobial residue in muscle tissue.
- Eimeria stiedae, the one species that multiplies in the liver, is considered to be the most pathogenic coccidium of rabbits. Like the other forms, it enters the intestinal wall, but it migrates to the bile ducts, where it reproduces. Infections lasting more than 16 days can be recognized by white circular nodules on the liver (Figure 15). The parasite multiplies in the epithelial cells of the bile ducts, which become thickened and tortuous and contain a vast number of oocysts. In the early stages of infection, there are no unusual symptoms. Then appetite decreases, a potbelly develops, and death sometimes follows. In moderate infections, there is no mortality, but disfigurement of the liver makes it unmarketable; hence this type of coccidiosis always is of economic significance.
- Liver coccidiosis is acquired in the same manner as intestinal coccidiosis. The control measures also are similar; however, liver coccidiosis can be controlled more easily by proper management. When the disease does occur, feed containing 0.025 percent sulfaquinoxaline is an effective treatment. It can be fed at this level for 3 weeks; use it only until management control measures can be introduced.
- Also known as “ketosis,” this disease is a toxemia of pregnancy that is most common in first litter females. Signs of ketosis are dullness of the eyes, sluggishness, respiratory distress, prostration, and death after 1 to 4 days. The disease occurs in the last week of pregnancy and is much more prevalent in obese animals. The probable major cause is starvation with subsequent metabolic effects on the doe and young. For some reason, there is a loss of appetite and failure to eat. This may be the result of minor digestive upset (hairballs in the stomach are common), an abrupt reduction in exercise, or a ration containing too little digestible carbohydrate. When carbohydrate energy declines, body fat is mobilized for energy, and ketone bodies are produced and enter the bloodstream. The liver becomes fatty and appears brown and soft.
- Birth of the litter or abortion is apt to be curative if either occurs shortly after the onset of signs. Injections of fluids containing glucose may reverse the breakdown of body fats and halt production of ketones. Junior does should not be too fat when bred for the first litter.
Vitamin A Deficiency
- Low-grade vitamin A deficiency adversely affects the reproductive performance of females, often before other signs are noted. Premature degeneration of the ovum and reduced numbers of fertilized ova result. Resorption of the fetus or abortion during late gestation also is noted.
- Rabbits born to females fed a diet deficient in vitamin A may be hydrocephalic at birth. Hydrocephalus, or “water on the brain,” is characterized by distention of the portion of the skull that covers the brain. Cases may not be apparent because the young die soon after birth or are born dead. Animals that live show signs of nervous system involvement. Wryneck, loss of equilibrium, and incoordination persist for several days or weeks. Impaired coordination may prevent animals from eating, and eventually they die of starvation. Enlargement of the head is caused by increased pressure within the brain. On cut section, the ventricles (cavities) of the brain are greatly enlarged and filled with a clear, colorless fluid.
- Hydrocephalus is caused by low maternal blood levels of vitamin A throughout the gestation period. When maternal blood levels fall below 20 micrograms (ug) per 100 ml serum, hydrocephalus appears in a large percentage of the young. Commercial diets, in general, supply adequate levels of vitamin A; however, the vitamin does deteriorate after prolonged storage of alfalfa hay.
- It has been shown by workers at Oregon State University’s Rabbit Research Center that excess levels of vitamin A can cause the same signs and symptoms as deficiency of the vitamin. Low fertility, abortions, resorption, and hydrocephalus were seen in does given excessive vitamin A in the diet. Excess vitamin A may be a problem if a vitamin premix is added to rabbit diets containing high levels of alfalfa.
Vitamin E Deficiency
- Infant mortality, characterized by death of entire litters at 3 to 10 days of age without clinical signs prior to death, has been associated with vitamin E deficiency. Affected infants do not reveal any gross lesions of diagnostic significance. Producing females become less fertile as the deficiency progresses. The problem can be treated because adequate supplementation of vitamin E will stop infant mortality and correct infertility. Alfalfa hay is a suitable source of vitamin E in commercial rations, and 8–9 mg/100 grams (g) feed is adequate.
- Malocclusion and tooth overgrowth, or “wolf teeth,” have long been recognized as common problems in rabbit colonies. The dental formula of the rabbit is: incisors 2/1, canines 0/0, premolars 3/2, and molars 3/3. Constant chewing and gnawing keep the teeth ground down to proper length and size. When the lower jaw is shorter or longer than the upper jaw or teeth are damaged, malocclusion of the incisors might result in overgrowth (Figure 19). The cheek teeth (premolars and molars) meet and grind evenly in normal animals. These teeth continue to grow and depend on constant grinding against opposing teeth to maintain their shape. If there is a malposition of the jaw, broken teeth, or malformation, overgrowth will occur in the cheek teeth similar to that which occurs in the incisors.
- Signs of malocclusion are gradual loss of appetite and weight. Both sides of the mouth may become stained with saliva. Animals become progressively listless, dehydrated, and unable to chew properly. Complications are abscessed teeth, growth of teeth into the upper jaw, and death from starvation.
- Malocclusion of the incisors can be corrected temporarily by cutting back the teeth so the animals can eat and attain good condition before slaughter.
- However, never use these animals as breeding stock because many types of malocclusion are inherited. Young rabbits occasionally pull on cage wires or feeders with their teeth and cause misalignment, which also results in malocclusion. This type of malocclusion is difficult to differentiate from inherited malocclusion. Therefore, the best solution is to regard all malocclusion as inherited. The recessive malocclusion genes can be eliminated from a breeding herd by selective breeding.
Splay Leg and Ataxia
- Splay Leg
- Splay leg in rabbits is due to one or more recessive genetic factors. The condition might be similar to the hip dysplasia found in certain breeds of dogs.
- The disease is characterized by an inability to put weight on one or both hind legs, and might even involve all four limbs. The limbs are twisted so the animals have a double-jointed posture. Affected animals are not paralyzed. They eat normally, seem to be well, and move by wriggling along on their belly and chest. The pathologic effects are limited to the hip and shoulder.
- Ataxia (muscle incoordination) resembles splay leg in some respects. It is, however, a lethal recessive genetic factor. The disease usually appears when the animal is 2 to 3 months of age and runs its course in 30 days. In ataxia, the nervous system is involved, and at first the animal might not be able to use its hind legs effectively. Later the animal cannot move, and its body temperature drops below normal until death ensues.
- Most cases of cannibalism are the result of a diet that is inadequate in either quality or quantity, injury or abnormality in a baby rabbit, or disturbance of the doe following kindling. Proper feeding and seclusion at kindling usually prevent the tendency. A valuable doe that destroys her first litter should be given another chance. If she continues to kill young, she should be culled from the breeding population.
- Heat prostration results from 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, animals breathe rapidly and become comatose.
- Provide relief to adult animals suffering from the heat by spraying 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 circulation 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.
- Draining water lines or crocks and refilling with cold water for immediate consumption aid in reducing rabbits’ body temperature. It is also helpful to change breeding schedules to reduce the number of late-pregnancy does in the hottest part of the summer.
- Sore hocks are inflamed bare spots, devoid of fur, found on the bottom surface of the hind legs (Figure 20). In severely affected cases, secondary infections with Staphylococcus occur. Both front and hind feet might become involved. As the hocks of the hind feet become painful, the animal throws more weight to the front feet, adding stress to the front feet and causing them to become affected. Wet, dirty hutch floors and the irritating action of urine salts are predisposing factors. The breed also is a factor in the development of sore hocks; the disease is seen more often in large breeds than in smaller breeds. Rex rabbits are prone to the disease because of thin foot pads.
- Treatment of sore hocks often is nonproductive. Even if treatment is successful, the lesion almost always returns, and the animal seldom is useful as a breeder. The best method of treatment is prevention. Prevention is accomplished in three ways. First, cull all affected breeders from the breeding herd because of a genetic predilection for sore hocks (thickness of the foot pad). Second, clean cage floors daily and never allow manure to hang on cage floors. Third, inspect cage floors frequently for rough spots or rusty areas.
- Spontaneous tumors in rabbits rarely are reported because the animals are slaughtered before they reach the age at which tumors are most apt to occur. With the increasing use of rabbits as laboratory animals, interest in these growths can be expected. Tumors have been observed in the uterus, kidneys, blood, lymph nodes, bones, testicles, skin, and other organs. Adenocarcinomas of the uteri are not uncommon in does over 2 years of age. Usually they are multiple and occur in both uteri. Most cases of lymphosarcoma (tumors of cells from lymph nodes) occur in mature females. Neoplastic cells are found in numerous body organs, but the most outstanding lesions are in the kidneys. Another tumor originates from embryonic cells in the kidneys (embryonal nephroma) and is observed with some frequency in domestic rabbits.
- Rabbits take soft fecal pellets from the vent and swallow them intact. This is a natural physiological process for rabbits and should not be misinterpreted as a nutritional condition or depraved appetite. Coprophagy is practiced at night by tame rab-bits and during the day by wild rabbits in their burrows. Fermentation of the feces in the large intestine supplies an abundance of certain B vitamins to the fecal pellets, probably improves the quality of the protein in the soft pellets, and improves fiber breakdown by bacterial action. By permitting a second passage of food through the digestive tract, the rabbit gains additional nutritive value from the food.
Winter Breeding Depression
- A very common occurrence in rabbitries in cold climates is a decrease in productivity during the winter. The syndrome usually has these common elements: small litters, abortions, weak litters that can’t nurse, does that don’t have enough milk, and does that will not breed. All of these factors lead to a decreased number of fryers toward the end of the winter. Although many causes for this syndrome have been postulated, the basic problem is inadequate nutrition.
- Breeding does (and sometimes bucks) require more energy in cold weather to keep warm. If you use a restricted feeding program (rabbits are not fed all they want), increase the amount of feed in cold weather. Otherwise, the doe will not have enough food calories to provide body heat and energy for the reproduction process. Reproduction will be suspended until adequate nutrition is available, which usually occurs as warmer weather arrives.
- The treatment for this syndrome is either to increase gradually the amount of feed (usually to about double) or to increase the amount of energy in the diet by increasing the amount of carbohydrate or fat.