Colitis literally means inflammation of the colon, which is part of the large intestine. Think of the digestive tract as one long tube, starting at the mouth and ending at the rectum. Before reaching the rectum, the byproducts of digestion pass through the colon, where much of the water content is absorbed. When a dog’s colon is inflamed, it may cause diarrhea, possibly with blood or mucus.
Risk factors and detection
Colitis affects dogs of all ages. Boxers develop their own type of colitis called histiocytic ulcerative colitis, named for the type of cells found in the colon. Dogs who spend time outdoors are more likely to encounter parasites and bacteria that cause colitis, and those who eat foods other than dog food also may experience problems. Very nervous animals can develop a form of colitis known as irritable bowel syndrome.
Signs of colitis include:
- blood or mucus in your dog’s stool
- excessive gas
- diarrhea
- frequent defecation
- unproductive defecation.
Dog owners often mistake an inability to defecate for constipation. Either way, make an appointment to see your veterinarian. You may think it’s not necessary, since dogs with colitis usually maintain their weight, energy level, and appetite. But colitis may be the first sign of a more serious problem, such as cancer.
Your veterinarian will ask about your dog’s eating and elimination habits. Then he or she will perform a thorough examination, including a digital rectal exam and a fecal exam. A fecal exam often reveals the cause of colitis, such as a rich meal, a bone or other foreign material in the rectum, or parasite eggs visible under the microscope. Sometimes the examination identifies a mass in the rectum, which could be a benign polyp or a cancerous tumor. If the signs of disease are ongoing, your dog may need blood tests and additional fecal tests. In some cases, the only way your veterinarian can make a diagnosis is to anesthetize your dog, examine her colon with an endoscope, and obtain a biopsy sample.
Causes of colitis include parasites, such as whipworms, hookworms, and Giardia; bacterial infections with Campylobacter, Salmonella, or Clostridium species; and fungus or algae infections. Also, food allergies, inflammatory bowel disease (in which different types of white blood cells infiltrate the colon’s lining), cancer, polyps, stress, and dietary indiscretion (when your dog overeats or ingests something she shouldn’t) can all contribute.
Prevention and treatment
Prevention, of course, depends on the cause. Keep your dog away from moist outdoor areas and stagnant water to reduce exposure to parasites and bacteria. Some monthly deworming products prevent and treat gastrointestinal parasite infections, and a new vaccine prevents giardiasis.
Feed your dog the same type and amount of dog food each day to eliminate colitis caused by dietary indiscretion. Your veterinarian may recommend changing to a special food to prevent recurrence of some types of inflammatory bowel disease. If your dog has irritable bowel syndrome, try to identify and minimize the source of her stress.
Once your veterinarian identifies the underlying cause of colitis, treatment may be as simple as withholding food for 24 hours, changing to a high-fiber or hypoallergenic food, or administering medication once or twice a day. If the cause is a bacterial infection, the doctor will prescribe an antibiotic. If the culprit is inflammatory bowel disease, your dog may require lifelong treatment. And in rare cases, your dog will need surgery to remove a mass.
