Colitis, Canine

Large Bowel Diarrhea (Colitis)

By Dr. Karen Burgess

Your pet has clinical signs of large-bowel (colon) disease. Signs typically include soft stools with or without mucous or fresh blood, increased urgency to defecate, and straining to defecate (small amounts of stool in numerous locations). There are many ways to treat colitis and what might work for one pet may not work for another. While the goal is to cure the problem, in many cases the underlying cause cannot be completely resolved and control of symptoms becomes our goal.

There are three different approaches to controlling colitis; low residue, novel antigen/hydrolyzed protein and high fiber diets. Typically we will start with one of these three products and evaluate for response. If improvement is not noted after a period of time, another approach may be recommended. A commercially made prescription version of these diets is recommended as these are made under controlled conditions which ensure reliability. While feeding any of these diets, it is very important that no other food or treat be given unless specifically approved by your veterinarian.

  • Low-Residue diets are made of highly digestible ingredients therefore leaving less material for the colon to deal with.
  • Novel antigen diets are made with a new protein and carbohydrate source that a pet has not been exposed to previously. Hydrolyzed protein diets contain nutrients that have been reduced to a size that is not recognized by the immune system. Both of these diets are used to help rule out symptoms that may be related to a specific component of the diet (food sensitivity or food allergy). These diets usually need to be fed for a minimum of 8 weeks to evaluate for response. It is extremely important that now other food items pass your pet’s lips during this trial period.
  • High fiber diets bulk up the stool thus enhancing gut mobility and improve cellular health. Metamucil and canned pumpkin are other options to help bulk up a diet.

Intestinal deworming
An intestinal parasite exam is performed on a fecal sample to help identify parasite issues. In some cases, eggs may be transiently passed or not detected on a single sample. For this reason a prophylactic broad spectrum deworming is often administered to ensure that parasites are not a contributing factor in cases of colitis.

There are several different medications that may be used in conjunction with diet.


  • The bacteria in the colon can become imbalanced and contribute to signs of colitis. Metronidazole and Tylan are common antibiotics used in the management of colitis in the short and sometimes even long run. In addition to assisting with bacterial loads, these medications also have anti-inflammatory and immune-modulating effects that can also help the gut.


  • Steroids suppress inflammation and at high doses are immunosuppressant. While very beneficial when indicated, steroids have numerous known side effects and should ideally only be used in diagnosed cases of steroid responsive diseases (ex. Inflammatory Bowel Disease). Once steroids have been started they can alter future diagnostic test results or hinder response to other treatments (in the case of cancer).

Anti-inflammatory drugs

  • Anti-inflammatory drugs that target the gut are typically well tolerated and have somewhat lower risk of negative side effects.


  • While not 100% proven to help with gastrointestinal disease, there have been promising results with the use of probiotics that provide pet’s with a dose of “good” bacteria in an effort to normalize their intestinal flora. With no real side effects, this nutraceutical should be purchased only from your veterinarian to ensure quality of the product.