Inflammatory Bowel Disease in Cats

Inflammatory bowel disease (IBD) is not a specific disease. Rather, it is a specific reaction that the stomach or intestines have to chronic irritation and inflammation.
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If the stomach is involved, your cat will have chronic vomiting. This is the most common form. If the intestines are involved, chronic diarrhea will occur. In some cats, both parts of the digestive tract are involved, so both vomiting and diarrhea occur. If the disease occurs for several weeks to months, weight loss and poor appetite are common. The frequency can vary from daily to every few weeks or months even. 

IBD is most common in middle-aged to older cats (generally between ages 5 and 12), but it can occur in younger cats as well.

There are many diseases with similar clinical signs so there can be multiple steps involved in diagnosis to help rule out other causes as well.

The chronic irritation that causes IBD stimulates the body to send cells from the immune system to the affected area. The most commonly found cells are lymphocytes and plasmacytes. Thus, the disease is diagnosed when these cells are identified in abnormal levels in the tissue. A pathologist is responsible for this part of the diagnosis; his/her report usually calls the disease lymphoplasmacytic gastritis (relating to the stomach), lymphoplasmacytic enteritis (relating to the intestine) or lymphoplasmacytic colitis (relating to the colon).

In order to obtain these cells, a biopsy is required. In most cases, an endoscope is passed into the cat’s stomach or colon (while the cat is under anesthesia). A tiny biopsy instrument is passed through the endoscope and used to take small samples of the lining (mucosa) of the affected organ. These samples can also be obtained surgically through an abdominal incision, however an endoscope it less invasive.

The tissue reaction that occurs in the stomach or intestines is diagnosed with a biopsy. However, determining what causes the tissue reaction to occur requires further testing. Tests or treatments should be performed to rule out stomach and intestinal parasites, cancer and infections. Diseases such as hyperthyroidism, diabetes and pancreatitis should also be considered, though these will be ruled out by blood testing before an endoscopic biopsy is recommended. In many cases, the cause cannot be determined. IBD can be present concomitantly with other diseases as well. An abdominal ultrasound can also assess the thickness of the intestines and suggest IBD or lymphoma (a cancer that causes similar signs) as the cause and rule out other diseases prior to pursuing biopsies.

The ideal way to treat this problem is to diagnose the underlying disease that is causing the reaction. Sometimes the above mentioned tests will do that and sometimes a cause cannot be found. In the latter situation, the disease is called idiopathic. This means that a disease is present, but there is no known cause. Many cases of IBD are considered idiopathic.

Some cats with IBD respond to a change in diet. A prescription food that contains a strict novel protein source that is new to the cat, or a completely hydrolyzed protein diet is common. A true food trial requires that the test diet be fed exclusively for 2-3 months. If dietary therapy is not successful or feasible, drugs are used to suppress the inflammatory reaction. The type of drug chosen is dependent on the severity of the clinical signs and the biopsy result. 

New studies show the importance of GI bacteria contributing to the development of IBD, and newer therapies include adding fiber and probiotics, as well as supplementation of folate or vitamin B12 if they are deficient.

Long-term therapy is required for many cats. Generally, a cat is treated for a few months before the medication is weaned or discontinued. If the signs of vomiting or diarrhea recur, medication is resumed. Medications commonly used long-term include metronidazole or prednisolone (a corticosteroid). 

Some cats are meticulous groomers and typically swallow hair every day. Since hair is not digestible, it could easily be a source of chronic irritation to the stomach or intestines. Frequent brushing and the use of hairball medications are recommended to cats with IBD, especially if they have a history of vomiting or passing hairballs.

If a response to diet change occurs, the cat can be maintained on this diet for the rest of his/her life (as long as it is balanced). If a response occurs to corticosteroids or drugs that change the motility of the stomach, the long-term prognosis is also good if administration of the drug is feasible. However, if there is no response to diet or corticosteroids, the prognosis is more guarded. At that point, further testing is suggested to see if an underlying disease can be found. Long term use of cortisosteroids or immunosuppressives can have other risks which should be discussed further with your veterinarian.

It is helpful to monitor them for signs of recurrence as well as frequency of any clinical signs like vomiting or diarrhea. You can check their weight regularly as well to detect any early signs of weight loss. Monitoring carefully at home can help detect relapses sooner and can lead to earlier adjustments in long-term medications/therapies.