Inflammatory Bowel Disease in Cats
There are three bowel problems in cats characterized by chronic and protracted diarrhea, sporadic vomiting, malabsorption and, in long-standing cases, weight loss,anemia, and malnutrition. Together, these are classified as inflammatory bowel disease (IBD). Some affected cats show clinical signs in a cyclical pattern, while others are constantly in discomfort.
All of these diseases are immune-mediated reactions of the gastrointestinal system to food, bacteria, or parasite antigens. These reactions get out of control, with large numbers of inflammatory cells collecting along the gastrointestinal tract and interfering with digestion and absorption. These syndromes can be managed but are seldom cured, and over the long term may lead to ulcers or cancer, such as lymphosarcoma.
Other health problems, such as parasites,hyperthyroidism, and kidney disease, must be ruled out first. Blood work and ultrasound or X-ray studies of the gastrointestinal tract may be needed.
The role of bacteria in these syndromes has not been clearly established in cats but has been suggested, since cats tend to have higher concentrations of bacteria in their small intestines than many other mammals. This may be related to their being obligate carnivores and having a relatively short intestinal tract. Some scientists believe that cats fed a high-protein, low-carbohydrate diet that is more like a wild cat’s natural diet are less likely to develop these problems.
In each disease in the IBD complex, a different type of inflammatory cell (plasma cell, eosinophil, lymphocyte, macrophage) accumulates in the mucous lining of the small or large intestines. Pancreatitis and intestinal cancer may cause similar signs. A definitive diagnosis is made by endoscopy or exploratory surgery, during which biopsies are taken of the intestinal wall.
Treatment: This is an illness for which the realistic goal is control, not cure. Treatment tends to be lifelong for most cats. Although the exact medications may vary for the three versions of IBD, all three types often respond, at least partially, to dietary changes as described for lymphocytic-plasmacytic enterocolitis. Along with immunosuppressive drugs such as prednisolone and azathioprine, omega-3 fatty acids, antioxidants, and probiotics such as acidophilus may be helpful. Metronidazole, which is used to lower bacterial counts, can reduce symptoms. Budesonide is a new drug being looked at for treating IBD. This is a version of a corticosteroid, but it may have milder side effects. More research must be done before this drug can be recommended.
This is the most common inflammatory bowel disease in cats. Lymphocytes and plasma cells are the predominant inflammatory cells seen on biopsy of the small and large intestines. The disease has been associated with giardiasis, food allergy or intolerance, and an overgrowth of intestinal bacteria. Vomiting is a common sign but is not present in all cases.
Treatment: An antibiotic (metronidazole) is given to treat bacterial overgrowth and giardiasis. Immunosuppressant drugs such as azathioprine (Imuran) and/or prednisone are used if other treatments are not successful. As a general measure, the cat should be placed on a hypoallergenic diet, either homemade (baby foods or boiled chicken) or commercially obtained from your veterinarian. The diet should be highly digestible and low in fat. If colitis is present, fiber may need to be added. A homemade diet may be developed by consulting a veterinary nutritionist. Raw diets are not recommended because the cat already has a stressed immune system.
On biopsy, eosinophils may be found in the stomach, small intestine, or colon, and the eosinophil count in the blood may be elevated. Some cases are thought to be associated with food allergy or the tissue migration of roundworms and hookworms.
Treatment: Treatment involves the use of high-dose corticosteroids, such as prednisolone, that are tapered as symptoms are controlled. The cat should be tested for food allergies and intestinal parasites and treated accordingly. Dietary changes, as described for lymphocytic-plasmacytic enterocolitis, may be beneficial. This form of IBD is the most difficult to treat successfully and has the poorest outlook.
Granulomatous (Regional) Enteritis
This is a rare disease, similar to Crohn’s disease in humans. There is thickening and narrowing of the terminal small bowel due to inflammation of surrounding fat and lymph nodes. Macrophages, which are cells, found in tissues, that fight infections, are found when the colon is biopsied. The diarrhea contains mucus and blood. Biopsies are processed with special stains to exclude histoplasmosis and intestinal tuberculosis.
Treatment: Corticosteroids and immunosuppressive drugs are used to reduce inflammation and scarring. A course of metronidazole may be of benefit. Surgery may be required for a strictured bowel.