Inflammatory Bowel Disease (IBD)

. Inflammatory bowel disease (IBD) most commonly causes signs in cats such as vomiting, diarrhea, weight loss, and appetite changes. The signs may come and go, but are usually present for long periods of time. IBD is often called a “diagnosis of exclusion” because diseases such as parasites, viruses, tumors, food allergy, intestinal obstructions, and metabolic problems must all be ruled out.

Your veterinarian will likely begin with a thorough history and physical examination and then proceed to diagnostic testing such as a fecal examination, blood tests, X-rays and ultrasound. Blood tests may be normal, or may show nonspecific changes, but are important for evaluation of other organs such as the kidneys, liver, and thyroid. The X-rays are used to rule out intestinal diseases such as blockage or tumors. Abdominal ultrasound can evaluate the thickness of the intestinal walls, and look inside the liver, pancreas, and other organs.

To diagnosis this disease however, a sample of tissue (biopsy) from the intestine must be taken and evaluated by a pathologist. This sample can be taken by using endoscopy, in which a small fiber-optic camera is passed through the cat’s mouth into the stomach and small intestine. Tiny bites of tissue are taken. Biopsies can also be done by traditional exploratory surgery. For both procedures your cat will be under anesthesia, and the costs are usually comparable. Limits of endoscopy are that the samples are only taken from the inside surface of the intestine, and the equipment is not long enough to reach all of the intestines. Surgery, while more invasive, allows for full-thickness samples to be taken and for all of the abdominal organs to be evaluated and biopsy samples taken if needed.

Biopsy results show inflammatory cells [white blood cells] filling the walls of the intestines, thickening them and leading to decreased absorption of nutrients as well as altered motility [contraction of the intestines that moves the food]. To complicate the matter, in some cats the pancreas and liver/gall bladder may also be affected.

Treatment for this disease usually involves a combination of food and medication. There is no surgical treatment in cats.

Because food allergies can produce similar symptoms and look similar on biopsy, many veterinarians recommend a hypoallergenic food trial early in treatment. The recommended foods are highly digestible, easily absorbed, and contain a novel protein. A novel protein is either one that your cat has never seen before (some examples include duck, venison, and kangaroo) or a protein that has been broken up into such tiny pieces that your cat does not recognize it as a protein. Some cats respond well to increased fiber, such as oat bran, pumpkin or unflavored psyllium. Your veterinarian can recommend the most appropriate food and supplements for your cat.

Rarely, diet alone does the trick, and the diarrhea and vomiting both resolve. However, most cats require some sort of medication. Two types of medications are frequently prescribed to treat this disease: antibiotics, such as metronidazole, and immune system suppressants, such as corticosteroids. Steroids are initially given at a high dose, and then slowly tapered over weeks-to-months to the lowest effective dose. With treatment, the signs of IBD can often be controlled, even though the disease is not cured.

Can IBD progress to become lymphosarcoma (LSA) cancer? The answer is no one knows for sure, but one study did demonstrate that some cats with lymphosarcoma had previously been diagnosed with IBD. Severe IBD can look similar to early LSA in the biopsy taken via endoscopy. If there is uncertainty, a surgical biopsy should be performed.

What about just treating with prednisone without getting the biopsy first? We must be cautiousabout treatment with steroids prior to a true diagnosis of IBD: most lymphosarcoma will temporarily respond to steroid treatment, but without other chemotherapy the cancer will relapse and be more difficult to get into remission. Steroid treatment also makes it more difficult for the pathologist to read the biopsy because it leads to certain changes in the tissue.

There is no cure, but with medication and diet we can usually control the clinical signs.

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