Inflammatory Bowel Diseases of cats are a diverse group of chronic gastrointestinal conditions caused by infiltration of the lining of the gastrointestinal tract with inflammatory cells. IBD may involve the stomach, small intestine, or colon (or any combination thereof) and is classified based on the type(s) of inflammatory cells found in the gastrointestinal wall.

The cause of IBD is unknown, but may involve a hypersensitivity reaction to antigens (bacterial, food, or self-antigens) in the gastrointestinal lining (mucosa). This may result from a primary disorder of the gastrointestinal immune system or from events that occur secondary to mucosal injury and permeability. Chronic inflammation of the bowel may become self-perpetuating when loss of mucosal integrity allows bacterial or dietary proteins to enter the intestinal lining, where they incite further immune reaction and inflammation.

Affected cats show chronic gastrointestinal problems for weeks or years. Clinical signs vary based on the location and severity of inflammatory cell infiltration, with the most common symptom being intermittent vomiting. Diarrhea is the second most common sign and can result in weight loss despite an excellent appetite. Some cats have colitis, which causes them to defecate small amounts frequently. Occasionally, blood and mucus are found in the feces. Many other diseases have similar clinical signs. Other causes of inflammation must be ruled out before a diagnosis of IBD can be reached.

Diagnosing of IBD depends on:

• Establishing that the condition is chronic (weeks not days)

• Excluding other causes of intestinal inflammation (parasitic, infectious, and dietary). This may involve fecal analysis, blood tests, and a hypoallergenic feeding trial

• Establishing the presence of intestinal mucosal lesions by biopsy and histopathologic examination

Once other causes of intestinal inflammation have been ruled out and IBD has been confirmed by intestinal biopsy, medication to control the intestinal inflammation will be administered. Treatment involves a combination of medication to suppress the immune stimulation in the intestinal tract, a hypoallergenic diet, and stress reduction. Remission can take 4-6 weeks in severely affected cats, after which most medication can be tapered to a lower dose. In cats with signs suggestive of colitis, a fiber-enriched diet will sometimes produce a regression of signs. Fiber supplements such as psyllium (Metamucil) 1-2 tsp. daily or bran cereals (3-5 Tbsp.) may be added to regular diets or a fiber-enriched diet such as W/D or R/D may be fed. Regardless of the treatment, clinical signs may reoccur. Medication is used to control relapses and induce remissions, but usually does not result in a cure.