Colitis in Dogs

There are two forms of colitis: acute and chronic. Acute colitis has a sudden onset of symptoms, and often resolves quickly without significant treatment. Stress is the most common cause of acute colitis. Dietary indiscretion, such as eating garbage, is another common cause of acute colitis. Not all underlying conditions leading to acute colitis are minor, so the presence of any other symptoms is useful for evaluating a dog with a sudden onset of large bowel diarrhea.

Chronic colitis lasts for more than 2 weeks and is more commonly associated with infections, allergies, autoimmune disease, or dietary intolerance. Further diagnostic testing and more specific treatment is usually necessary to successfully manage chronic colitis.

A diagnosis of colitis localizes the source of the symptoms to the colon, and this may occur in association with inflammation of other parts of the digestive tract. Dogs with colitis may present with additional symptoms like vomiting and appetite loss, indicating gastritis (inflammation of the stomach) and gastroenteritis (inflammation of the stomach and small intestines) as well.

Colitis is a common condition in dogs. Most cases of colitis are associated with stress or dietary indiscretion, and generally resolve quickly with appropriate treatment. More severe conditions, such as infections, allergies, or autoimmune disease, also cause colitis. These conditions require significant trial and error or diagnostic testing to determine the best route of treatment, and dogs often relapse despite appropriate care. Many of these conditions require life-long treatment and management.

Colitis is a very broad term, referring to inflammation of the colon.

Inflammation in the colon prevents it from absorbing water in the intestinal contents. This extra fluid remains in the feces, resulting in diarrhea. Colonic inflammation also increases the rate of fluid moving through the colon, causing many dogs to have increased bowel movements and increased urgency to defecate.

A history of soft stools or diarrhea with increased bowel movement frequency suggests a diagnosis of colitis. If symptoms have suddenly occurred, then stress-induced colitis or dietary indiscretion is presumed. These cases are generally treated without further diagnostic testing, using anti-inflammatory medications that target the colon. Veterinarians may recommend fasting the dog for up 1-2 days, then switching to a bland diet such as boiled rice and chicken to help rest the colon and give it time to recover.

If treatment is unsuccessful, or the dog has had gastrointestinal symptoms for more than 2 weeks, then further investigation is required.

Diagnostic tools include:

• Blood work
• Fecal analysis
• Diagnostic imaging
• Testing the feces for specific bacterial or parasitic DNA
• Colonoscopy
• Biopsy of the colon

Treatment depends on the underlying cause of colitis. Any infections are treated first, using appropriate anti-parasitic or antibiotic medications. If symptoms do not resolve, then a dietary change is recommended.

Some dogs diagnosed with chronic colitis benefit from adding fiber to their diet, such as psyllium or wheat bran. The added fiber absorbs water in the intestinal tract and slows the movement of the colon, helping to resolve symptoms. Over time, the amount of fiber is reduced to see if symptoms return.

If a high-fiber diet is ineffective, then switching the diet to another protein is recommended. In cases of food allergy, switching the protein removes the allergen and allows the colon to heal.

Symptoms that do not resolve with either a high-fiber or new protein diet are often switched to a low-residue diet. These diets are almost completely digestible by the stomach, leaving very little intestinal content that enters the colon. Adding probiotics to repopulate the colonic bacteria is also helpful in many cases.

During these dietary trials, anti-inflammatory medications are often helpful to prevent further damage to the colon. If allergies or autoimmune disease are suspected based on biopsy results, then long-term anti-inflammatories or immunosuppressants are used to reduce the immune system’s effect.

Most cases of colitis caused by stress or dietary indiscretion resolve within several days with appropriate treatment. These cases have a good prognosis.

Treating chronic colitis is more involved, and reduction of symptoms often takes days to weeks to occur. Many causes of chronic colitis are related to lifelong conditions such as allergies or autoimmune diseases, which require long-term management. Complete resolution of symptoms is rare, as many dogs with chronic colitis relapse, even when treated.

Some causes of colitis are contagious, such as parasitic or bacterial infections. Maintaining dogs on routine deworming medications helps prevent parasitic causes of colitis. Other types of colitis such as those caused by dietary indiscretion or allergies can be prevented or reduced by maintaining a steady diet that the affected dog is able to digest without symptoms. All types of GI inflammation in dogs are reduced by preventing access to human foods and food scraps.

Colitis is common in dogs.

• Bland diet
• Antibiotics
• Probiotics
• Steroids
• Other dietary changes