Bacterial enteritis and diarrhea in
weaned and adult rabbits
Esther van Praag, Ph.D.
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In rabbits, health of the digestive system is considered as the basis of the general health of the animal. There is no specific and unique cause that leads to a disruption of digestive transit, but a combination of factors: stress, the shift from a milk diet to an herbivore diet in weaning rabbits, hygiene, parasites, molting and trichobezoar (mass of fur hair in the stomach) and dental problems. In response, rabbits respond with intestinal disturbances characterized by the onset of diarrhea. Newborns are not much concerned because they are protected by milk produced by the doe, which has antibacterial properties that prevent the growth of pathogenic bacteria. Newly weaned 4- to 7-week-olds suffer mainly from enterotoxemia with the almost complete destruction of the intestinal flora. After this age, young rabbits and adults suffer from mucoid enteritis, with partial destruction of the bacterial flora.
Diarrhea
Intestinal diarrhea in rabbits is favored by the following facts:
1. The rabbit is a very nervous animal which is unable to adjust well its alarm response (adrenaline discharge) to the gravity of the situation.
2. The rabbit has a particular intestinal physiology, characterized by coprophagy (cecotrophy - reingestion of feces produced in the cecum). During a period of stress, the hormone adrenalin is released in the blood, which affects the nervous system and will slow down the activity of the intestine. Passage of food is slowed down and coprophagie is stopped.
3. After a stressful event, the cecum becomes more alkaline. This will affect the intestinal environment, the intestinal bacterial flora and will allow the growth of pathogen bacteria such as Escherichia coli or different species of the Clostridium bacterium may become dominant.
4. The appearance of a disease in rabbits is generally delayed after a stress period, and diarrhea appears only 1 to 7 days after.
The clinical signs of digestive problems or enteritis in rabbits are fairly constant. The first signs, which last 1 to 3 days, remain generally unnoticed: decreased food intake by the rabbit and constipation. The watery cecal feces are generally not eaten. After the 5th day, moderate diarrhea, accompanied by skin dehydration appears. Diarrhea consists of small quantities of liquid feces which soil the anal region and hindquarter of the rabbit. Death can occur at this phase, sometimes even before the diarrhea appears.
Two or three days later, the acute form of the illness develops. The rabbit stops eating drinking and suffer from extensive diarrhea. Teeth grinding can be heard, as a result of severe intestinal pain and discomfort and the rabbit may suffer an agitated comatose state. At this stage prognosis is poor and the rate of mortality is high. Animals that remained comatose during a full day can, however, survive when given appropriate care, and recover within a few days.
A post mortem examination of the intestine show atypical lesions. During the acute phase of the disease, the intestinal wall appears bruised or congested. The content is watery. The cecum looks congested, marked with red brushstrokes, and is filled with gas and little food.
Causes
There are specific and non-specific causes for diarrhea.
Young rabbits respond badly to stress (especially during the post-weaning period), transport, to unidentified noises, to a new environment and to new persons or animals. Modifications of the diet or a diet low in fibers can, furthermore, lead to digestive disorders. Usually, food alone is not the main trigger of diarrhea, but rather its composition, such as a low percentage of crude fiber, too rich in carbohydrates or proteins, too finely ground food or improper watering, or the introduction of a new sort of vegetable or fruit.
Viruses and pathogen bacterial overgrowth of e.g. Corynebacteria sp., Clostridium sp., Pasteurella sp. and Escherichia coli cause enteritis. The occurrence of Salmonella sp. is, however, rare in rabbits. The presence of intestinal parasites such as trematodes (flukes), cestodes (tapeworms), nematodes (Parasitic intestinal worms), and protozoa (coccidiosis) can also lead to digestive disorders in rabbits, with onset of stasis and diarrhea.
Further causes of diarrhea include the administration of drugs or antibiotics (see: “Antibiotics dangerous for use in rabbits”), or the presence of nitrate in the drinking water.
Bacterial and Mucoid enteritis
Mucoid diarrhea is sometimes observed in growing rabbits and nursing does. The watery feces are mixed with mucus, a translucent and gelatinous substance. This particular type of enteritis has various causes, including bacterial overgrowth or nutritional deficiencies (lack of water and food low in fiber).
Bacterial enteritis develops very rapidly, within 3 to 4 days and leads to death before the appearance of diarrhea. Bacteria such as Clostridium perfringens and Escherichia coli cause intestinal enteritis. In healthy rabbits the number of Escherichia coli bacteria present in the fecal droppings is low (102-103/g drops), but in cases of diarrhea, they are systematically present in high number. The bacterium produces toxins, but it has been shown that these alone do not lead to the onset of diarrhea. It needs a supplemental source of stress to induce diarrhea, such as a non-balanced diet or a thermal choc (sudden change of weather, drop of temperature or atmospheric pressure).
Clostridium perfringens exists in 5 forms and is classified according to the production of toxins. These toxins induce local lesions in the intestine, but their action may also affect distant organs such as the liver and the kidney.
Escherichia coli possess five general mechanisms to invade the intestine and cause the disease. Sometimes there is production of toxins. The bacterium invades the intestine by adhering on the villi of enterocytes and begins to proliferate. The presence of toxins stimulates the secretion of water and electrolytes by the intestinal mucosa. Proliferation of bacteria and production of toxin together can lead to diarrhea.
Both above bacteria are often associated to the presence of coccidia.
Treatment
As the disease develops very rapidly, treatment of bacterial enteritis often comes too late because the evolution of the disease is fast and the rabbit is severally dehydrated. Antibiotics, including sulfonamide drugs, may help prevent the growth of pathogen bacteria. Anti-diarrhea product can help stop the diarrhea, e.g. Hylak, a concentrate of lactic ferments. Cholestyramine will bind toxins released by pathogen bacteria such as the alpha toxins produced by Clostridium perfringens. Probiotic powders or paste, although controversial, will support the growth of the endemic healthy bacterial flora.
If the rabbit is dehydrates, it should be given oral fluids with a syringe or subcutaneous fluids. If the rabbit refuses to eat, intake of food must be forced using a syringe. Various veterinary products are available to feed a sick rabbit. Homemade food can also be prepared, using the usual pelleted food, finely grinded in a coffee grinder, a few drops of olive oil and plant-based baby food (pumpkin, carrot, apple, etc.) diluted in lukewarm water in order to obtain a smooth paste that can be easily taken up in a syringe.
Even if controversial, virgin cold-pressed olive oil has several properties that help against constipation or diarrhea. Its presence in the intestine stimulates the secretion of digestive fluids such bile, lightly stimulates peristaltic movement of the intestine and lubricates the intestinal wall. It does, furthermore, promote the growth of healthy intestinal bacteria.
In the case of yeast overgrowth, food rich in carbohydrates should be reduced. The lack of sugars will lead to a decrease of the yeast population in the intestine. If this is not helping, an antifungal drug like nystatin can be given to the rabbit.
Plants with medicinal or other properties can help stop the diarrhea or help recovery of the rabbit after the disease. They are presented in the bellow tables.
Acknowledgements
All my gratitude to Prof. Richard Hoop (Institut für Veterinärbakteriologie, University of Zurich, Switzerland), to Kim Chilson (USA), and to Tal Saarony for the permission to use their pictures. Thank you also to Adar, Flora, and Stampi for their help in illustrating this article.
Further Information
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Jones JR, Duff JP. Rabbit epizootic enterocolitis. Vet Rec. 2001 Oct 27;149(17):532.
Hoop RK, Ehrsam H, Keller B. 10 years of rabbit autopsy--a review of frequent disease and mortality causes. Schweiz Arch Tierheilkd. 1993; 135(6-7):212-6.
Humphrey CD, Condon CW, Cantey JR, Pittman FE. Partial purification of a toxin found in hamsters with antibiotic-associated colitis. Reversible binding of the toxin by cholestyramine. Gastroenterology. 1979 Mar;76(3):468-76.
Licois D. Tyzzer's disease. Ann Rech Vet. 1986; 17(4):363-86.
Sinkovics G. Rabbit dysentery: 3. Diagnostic differentiation. Vet Rec. 1978 Oct 7; 103(15):331-2.
Patton NM, Holmes HT, Riggs RJ, Cheeke PR. Enterotoxemia in rabbits. Lab Anim Sci. 1978; 28(5):536-40.
Patton NM, Holmes HT, Riggs RJ, Cheeke PR. Enterotoxemia in rabbits. Lab Anim Sci. 1978; 28(5):536-40.
Tribe GW, Whitbread TJ, Watson GL. Fatal enteritis in rabbits associated with a spirochaete. Vet Rec. 1989; 124(22):595.
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