The function of the large intestine is to maintain fluid and electrolyte balance, absorb nutrients, provide an environment for normal intestinal bacteria and store feces temporarily. It is also known as the colon or large bowel. When the large intestines becomes damaged, either by inflammation, parasites or other causes, it will often result in diarrhea. Colitis in dogs can be short term or long term. The cause is often unknown but parasitic, bacterial or allergic causes can be suspected. There may be a defect in the immune system in the colon which may result in inflammation. It may also be due to dietary or bacterial factors, genetic predisposition, parasitic diseases or previous infections.
The symptoms can include constipation with the animal straining to pass feces, mucus in the stool, and blood in the stool. The feces may be more of a liquid consistency and of a small volume. Weight loss and vomiting are not normally associated with diseases in the large intestines, but can be symptoms of diseases in the small intestines. The cause of the inflammation will need to be found and treated. The veterinarian will perform a physical examination. Tests will also be performed, such as blood tests, fecal tests, endoscopy and a biopsy. The treatment will be based on the cause of the inflammation.
It may be necessary to withhold food for a day or two which allows the digestive system to rest. When feeding is resumed, dis-solvable fiber may be added. After a period of time, the dissolvable fiber may be reduced or removed completely and standard dog food can be fed without the diarrhea returning. When feeding is resumed, the owner may be asked to give the animal food with a protein that has not been eaten previously such as duck, lamb, venison or kangaroo. Doing this reduces the chances of the dog having an allergic reaction to the food proteins. It is important for the owner to follow the veterinarian’s instructions very carefully. A fiber supplement in the diet can help improve diarrhea in many animals.
The veterinarian may also prescribe some anti- inflammatory medication in addition to the dietary changes. A fiber supplement does not usually relieve the symptoms of diarrhea related to the large intestines alone. It may also be necessary to administer antidiarrheal medication until the inflammation is controlled. This is a short term medication and will not be prescribed for a prolonged period of time.