Bacterial enteritis in rabbits

 

Esther van Praag, Ph.D.

 

Warning: this file contains pictures that may be distressing to some persons

Intestinal disturbance in rabbits is the result of stress or underlying diseases. It is characterized by the appearance of watery feces or diarrhea. Young weaned rabbits aged between 4 to 10 weeks appear to be more prone to this problem than older adult rabbits. It rarely occurs in new-born rabbits, probably due the milk of the doe which has anti-bacterial properties.

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 - reinjestion 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 cecotrophy 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 Clostridium sp. 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.

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Adar and Flora caring for their sick friend Stampi, suffering from watery diarrhea (arrows)

 

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:  decrease in food intake by the rabbit, accompanied by constipation. The watery cecal feces are generally not eaten. After the 5th day, moderate diarrhea, accompanied by skin dehydration appears. It 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. It involves a stop of food and liquid intake and extensive diarrhea. Rabbits often grind their teeth as a response to severe intestinal pain and may suffer an agitated comatose state. At this stage the rate of mortality is high. It is nevertheless observed animals that were in coma for a full day can 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.

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Tal Saarony

Dirty bottom of a rabbit suffering from a bout of soft fecal of cecal material (arrow). When the production of soft fecals becomes chronic, alopecia can develop. The skin will become inflammed and painful.

Causes

Young rabbits respond badly to stress, transport (especially during the post-weaning period), 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.

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. Viruses and pathogen bacterial overgrowth of e.g. Corynebacteria sp., Clostridia sp., Pasteurella sp. and Escherichia coli cause enteritis. The occurence 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.

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).

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Kim Chilson

Mucus threads (left) or “plugs” (right) excreted among fecal material. The presence of mucus is often observed after the diarrhea is gone.

Bacterial enteritis develops very rapidly, within 3 to 4 days and may cause death before the appearance of diarrhea. The bacteria causing intestinal enteritis are known as Clostridia perfrigens and Escherichia coli. In healthy rabbits the number of E. coli bacteria present in the droppings is low (102-103/g drops), but in 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. Escherichia coli is occasionally found together with coccidia. For diarrhea to occur there must be another stress on the rabbit, such as unbalanced feeding or a thermal shock.

Clostridia perfrigens 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.

Prof. Richard Hoop

Prof. Richard Hoop

Prof. Richard Hoop

Microscopic view of Clostridium perfrigens and Clostridium spiriforme (top) and bacterial culture of C. perfrigens.

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.

Prof. Richard Hoop

Prof. Richard Hoop

Microscopic view of Escherichia coli and a pure culture on a Petri dish.

Treatment

As the disease develops very rapidly, treatment of bacterial enteritis often comes too late. Antibiotics and sulfonamide drugs will help prevent the growth of pathogen bacteria. Anti-diarrhea product can help stop the diarrhea, e.g. Hylak, a concentrate of lactic ferments. The administration of cholestyramine will bind toxins released by pathogen bacteria. Probiotic powders or paste, although controversial, will help the growth of the endemic healthy bacterial flora.

If the rabbit is dehydrates, subcutaneous fluids should be given. If the rabbit refuses to eat, it must be forced food, using a syringe.

In the case of yeast overgrowth, this can be treated by reduced the carbohydrates sources in the diet, or with nystatin.

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

Bryskier A, Doll J, Labro MT, Andrieu J. Role of Clostridium and its toxin in pseudo-membranous colitis. Ann Biol Clin (Paris). 1981;39(1):1-8.

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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