What is colitis?
Colitis simply refers to inflammation of the large intestine (colon). Colitis is most commonly used to describe diarrhea or loose stools associated with the large bowel. Large bowel diarrhea is another term for colitis.
What are the clinical signs of colitis?
Most dog owners report seeing frequent, small volumes of semi-formed to liquid feces. Many dogs will exhibit straining during and after defecation, and small amounts of bright red blood will often be passed near the end of defecation. Mucus or fat is seen in many cases of chronic colitis. Most dogs with colitis will exhibit a sense of urgency and need to defecate frequently. Vomiting occurs in less than a third of the cases of colitis or large bowel diarrhea. Weight loss is rare.
What causes colitis?
The causes of colitis include stress, infections (including Salmonella, Clostridium, and E. coli), and parasites (including, Giardia, Cryptosporidium, and whipworms), trauma, allergic colitis, and primary inflammatory bowel disease (lymphoplasmacytic, eosinophilic, granulomatous, and histiocytic types). Colitis may also occur after ingesting contaminated food, being in contact with infected dogs, or after chronic exposure to a wet environment. Stress colitis is one of the leading causes of large bowel diarrhea in all dogs.
Whatever the cause, the inflammation in the colon results in reduced water absorption and decreased ability to store feces in the colon. This causes the classic symptom of frequent small amounts of diarrhea, often with mucus or blood.
How is colitis diagnosed?
The diagnosis of colitis is based on your pet's clinical signs and history, microscopic evaluation of the feces, rectal examination, cytology, and blood tests. Additional testing such as radiographs (X-rays) to examine the colon and intestinal tract, colonoscopy and colon biopsies, fecal cultures, barium enemas, or ultrasound evaluation of the abdomen may be necessary in some cases. These tests are important to rule out conditions such as colonic tumors or polyps, irritable bowel syndrome, cecal inversion, and ileocecocolic intussusception (a rare condition in which the intestines 'telescope' or fold into themselves).
How is colitis treated?
The specific cause of colitis will dictate the appropriate treatment. Non-specific treatment includes fasting for 24 to 48 hours, feeding a low residue or hypoallergenic diet, increasing dietary fiber content, and adding fermentable fiber such as psyllium, beet pulp, or fructooligosaccharides (FOS) to the food. Some dogs with colitis will do better on low-fiber diets. See the handout "Nutrition for Dogs with Colitis" for more information on the role of diet and nutrition for dogs diagnosed with colitis.
Antimicrobial drugs may be indicated, depending on your dog's diagnosis. Anti-inflammatory or immunosuppressive drugs may be used in cases of inflammatory or immune-mediated colitis. Drugs that modify the colon's motility may also provide symptomatic relief.
What is the prognosis if my dog has colitis?
For most dogs diagnosed with colitis, the prognosis is excellent for a speedy recovery. Stress colitis is one of the leading causes of colitis in dogs. Treatment with a simple change in diet and medication to resolve the inflammation or infection in the colon is all that is required for most dogs. The majority of dogs experiencing stress colitis are back to normal within three to five days. Chronic, severe, or recurrent cases should have further diagnostic tests performed to determine the exact cause and proper treatment. For many dogs with chronic colitis, strict dietary control and careful use of medications keep the condition under control.