Colonic or Rectal Inflammation in Cats

Colitis and Proctitis in Cats

Histiocytic ulcerative colitis is a bowel disease which causes the lining of an animal's colon to thicken, with varying degrees of ulceration and tissue loss to the superficial lining. The thickening is due to the infiltration of various cells in the layers under the lining. When the colon becomes inflamed, there is a reduction in the colon's ability to absorb water and store feces, leading to frequent diarrhea, often with mucus and/or blood. Proctitis, conversely, is inflammation of the anus and lining of the rectum.

Inflammation of the colon and rectum can occur in any breed of cat.

Symptoms and Types

Some of the symptoms that may indicate inflammation of the colon or rectum are frequent bowel movements with only a small amount of stool, and prolonged straining after a bowl movement, as though the cat needs to pass more. Inflammation can also cause the stool to vary in consistency, from semi-formed to fluid, to diarrhea. Evacuating stool can further irritate the inflamed tissue of the colon and rectum, causing it to tear. As a result, chronic diarrhea will often have mucus and/or blood in it.

Irritation and ulceration of the colon can also lead to responsive vomiting and weight loss as a result of decreased appetite.


There are a variety of possible causes for this condition. The source can be from intestinal or rectal parasites; bacterial infection; fungal infection; or an algae infection (water based). It may also result from swallowing a foreign object or abrasive material, causing trauma to the intestines.

An otherwise healthy system can occasionally react to infection or disorder by retreating into itself. In some cases, urine or waste products will reverse into the body system instead of vacuating, resulting in abnormal amounts of waste products entering into the bloodstream. Urea, a waste product in urine, is one of the potentially harmful products that can enter the bloodstream. This can cause other problems for your cat's body as well, but one of the possible indicators of waste back-up is inflammation of the intestinal tract.

An inflamed intestinal tract can also be an indicator of inflammation in other organs. For example, long-term inflammation of the pancreas (pancreatitis) will irritate the intestines. Inflammatory or immune disorders, diet, and swallowing foreign objects can also affect your cat systemically, leading to inflammation of the colon and rectum.

Perhaps less worrisome than an immune disorder, but a critical consideration nonetheless, is the possibility that the condition is the result of allergies. If an allergy is presenting itself through inflammation of any organ or system, it will be important to pinpoint the source of the allergy. Reactions to allergens tend to intensify with further contact, sometimes with fatal results.

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