Inflammatory Bowel Disease in Dogs and Cats

The term inflammatory bowel disease refers to a condition that results when cells involved in inflammation and the bodies immune response infiltrate the lining of the GI tract. This infiltration thickens the bowel lining and interferes with absorption of nutrients and GI motility (the ability of the bowel to contract and propagate food).

With inability to contract absorb, the bowel’s function is disrupted. Chronic vomiting results if the infiltration is in the stomach or or upper small intestine. Liquid diarrhea with weight loss results if the infiltration is in the lower small intestine. Pudding-like stool, laden with mucus and/or fresh blood (colitis) results if the infiltration occurs in the large intestine. In the worst case scenario, the entire tract from top to bottom may be involved. Inflammatory Bowel Disease should not be confused with Irritable Bowel Occasional vomiting or diarrhea seems to be pretty standard for dogs and cats. After all, cats groom themselves and get hairballs, and dogs often lack dietary discretion and eat things they aren’t supposed to. However, many owners notice that their pets seem to have vomiting or diarrhea more often than it seems they should. It is often subtle where one notices that one is cleaning up hairballs or vomit piles more frequently than with previous pets. Or there could be a sudden realization that one hasn’t seen the pet have a normal stool in weeks or months. Typically, the affected dog or cat doesn’t seem obviously sick, nothing worse than perhaps a little weight loss, and of course, the chronic vomiting and/or diarrhea. Inflammatory bowel disease accounts for a large percentage of this type of presentation in dogs and cats. Dogs with inflammatory bowel disease more commonly present with chronic diarrhea, and cats more commonly present with chronic vomiting, although both presentations regularly occur in both species.

Achieving a diagnosis of inflammatory bowel disease is multifactorial. It is first important that the veterinarian rule out all other possible systemic possibilities for the set ot clinical signs. This includes kidney disease, endocrine disease, liver disease, parasites and cancer just to name a few. Therefore, an inflammatory bowel disease work-up should always begin with a good thorough physical examination, blood chemistry, complete blood count, urinalysis, fecal flotation, and abdominal x-rays.

Inflammatory bowel disease often does not show any abnormalities with these diagnostics. However, once all other systemic diseases have been ruled out, the veterinarian can begin to focus on resolving the inflammatory bowel disease.

The first consideration is to provide relief for the affected dog or cat. This consists of a course of metronidazole (effective antibiotic with anti-diarrheal properties) or other antibiotics to treat diarrhea, and/or metoclopramide (an anti-nausea agent) or Cerenia. Next, the patient should be placed on a hypoallergenic food trial, to rule out allergy to ingested protein sources. Many of these prescription diets exist for dogs and cats, two of the best being Royal Canin Anallergenic and Hill’s ZD Ultra. During the food trial the canine or feline patient cannot be fed anything else but the special diet.

At this point, if the dog or cat suspected to have inflammatory bowel disease improves with the medication(s) and does not ever have problems while on the hypoallergenic diet, then you have your solution – keep the pet on the diet. However, if improvement is temporary, but relapses once the medications have ceased, and you have been conscientious in feeding only the hypoallergenic diet, then more diagnostics need to be performed to formulate a long term treatment strategy. It is also important because there are other diseases that can primarily affect the GI tract of dogs and cats that can mimic inflammatory bowel disease that also escape detection by the aforementioned routine diagnostics. Examples of other diseases that can look just like inflammatory bowel disease include GI lymphoma , infection with a bacteria called H. Pylori, or an abnormal thickening of the stomach lining called hyperplasia.

The next mode of diagnostic that follows is endoscopy – colonoscopy for chronic diarrhea, or upper GI endoscopy for chronic vomiting. Endoscopy requires general anesthesia. Once the dog or cat is under, a scope with a camera on the end is fed into the GI tract. The GI tract can then be visualized by the veterinarian, looking for obstructive lesions such as masses, polyps, or plaques, as well as other lesions such as ulcers. If anything unusual is seen (or not seen), biopsy samples can be taken by the endoscope, and then submitted for cellular analysis.

The cornerstone of treatment for inflammatory bowel disease is suppression of the inflammation. In milder cases of large intestinal inflammatory bowel disease, the immunomodulating properties of metronidazole (Flagyl) might be adequate for control but usually prednisone is needed. Prednisone will work on inflammatory bowel disease in any area of the intestinal tract. In more severe cases, stronger immune suppression is needed (as with cyclosporine or azathioprine). Higher doses are usually used in treatment at first and tapered down after control of symptoms has been gained. Some animals are able to eventually discontinue treatment or only require treatment during flare-ups. Others require some medication at all times. Long-term use of prednisone should be accompanied by appropriate periodic monitoring tests due to the immune suppressive nature of this treatment.

Dietary manipulation may also be helpful in the management of inflammatory bowel disease depending on the patient’s interest in newer foods. The first step in dietary management of inflammatory bowel disease is fat restriction. Fat prolongs the time food spends in the stomach, which tends to promote nausea. There can also be undesirable interactions with fats and the bacteria of the intestine.

The second step in using diet as therapy for this condition is to use a protein source with which the patient is inexperienced. Such a novel diet is considered hypoallergenic and removes any immunological stimulation by dietary properties. While there is no hypoallergenic diet that is appropriate for all patients, many food companies have recognized the need for diets such as these and something may be specially ordered. Such diets are typically based on duck, venison, or rabbit proteins.

Some spets have recommended the use of what is called a sacrificial protein. This kind of treatment involves using one novel protein during initial treatment stages while the intestine is still inflamed and switching to another one when signs have been controlled. The theory is that an allergy to the initial protein is more likely to develop while the intestine is still diseased.

Insoluble fibers have been helpful in inflammatory bowel disease. They increase fecal bulk which stimulates more normal motility from the intestine. Slower stool passage results which enhances water absorption. Adding oat bran to the hypoallergenic diet may be helpful.

Is it at all Reasonable to just Try Treatment and Skip the Expensive Diagnostics?

Possibly. The problem with the prednisone trial involves the possibility of intestinal lymphosarcoma (also called lymphoma). This is a type of cancer that produces chronic diarrhea or vomiting just as inflammatory bowel disease can. Lymphoma is temporarily responsive to prednisone but the response is short-lived. Exposure to prednisone will make the lymphoma much more difficult to diagnose should biopsies be obtained later. Plus exposure to prednisone can lead to resistance to other medications. (This is less of a problem for cats, but in dogs even a few days of prednisone can make a lasting remission impossible to achieve.)

In short, if one tries prednisone without confirming a diagnose, harm can be caused should a lymphoma be present instead of inflammatory bowel disease.

Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital

Founder, CEO, Dr. Roger’s Holistic Veterinary Care

Article updated 2/12/2014