Colitis in Dogs
Dr. Bari Spielman
The history and clinical symptoms of dogs with colitis may vary and other illnesses may cause similar clinical symptoms. Therefore, several different diseases may initially be considered when evaluating a dog with symptoms compatible with colitis.
Common symptoms of colitis include loose stools that contain fresh (bright red) blood or mucus, frequent attempts to defecate, production of small amounts of stool, and straining to defecate.
Many types of inflammatory disorders can cause or be associated with colitis. These disorders collectively are known as "inflammatory bowel disease" because the clinical symptoms of several specific disorders are very similar to one another. Definitive diagnosis of the specific disorder is necessary for proper treatment. The different inflammatory bowel diseases include:
Lymphocytic-plasmacytic colitis is the most common inflammatory bowel disease of dogs. The definitive cause is not known, but it is thought to be caused by an overreaction of the immune system.
Histiocytic ulcerative colitis is characterized by ulcers and inflammation of the colon. It is seen most commonly in young boxer dogs.
Granulomatous colitis is an uncommon, poorly understood and severe disease of the colon that resembles Crohn's disease in people. The word "granulomatous" refers to the specific types of inflammatory cells that are present in the colon in this disorder.
Eosinophilic colitis is characterized by eosinophils (a type of white blood cell associated with allergic reactions or parasites) in the inflammation. The cause of eosinophilic colitis is unknown, but food allergy or parasitic infection may be involved.
Many infectious agents can cause symptoms of colitis:
Bacteria (Clostridia, Salmonella, E. coli, Campylobacter, and others)
Viruses (corona virus, parvo virus)
Fungal agents (such as the causative agents of histoplasmosis, pythiosis, and protothecosis)
Parasitic worms (whipworms, hookworms)
Parasitic protozoa (Trichomonas, Ameba, Balantidium, Giardia)
Dietary intolerance or allergic reactions also can cause colitis. In this case, colitis often occurs as a reaction to a specific protein, but also can be associated with lactose, high fat content and certain food additives.
Dietary indiscretion may cause acute (abrupt onset and short course) colitis. Examples of dietary indiscretion include eating spoiled food, overeating, ingesting foreign material and sudden dietary changes.
Colonic cancer can cause symptoms similar to those that occur in colitis such as fresh (bright red) blood in the stool, mucus in the stool, straining to defecate, increased frequency of defecation and painful defecation. The most common types of colon cancer in dogs are adenocarcinoma and lymphosarcoma.
Trauma, either internal (foreign bodies) or external (blunt trauma by an automobile) can cause colitis.
Intussusception (telescoping of the bowel into itself) can cause partial or complete blockage and can result in symptoms such as straining to defecate ("tenesmus")or blood or mucusin the stool.
Hemorrhagic gastroenteritis ("HGE") is a dramatic, potentially fatal disorder of unknown cause. It occurs primarily in small breeds of dogs. It is characterized by a sudden onset of profuse bloody diarrhea (often "raspberry jam" appearance and consistency) and occasional vomiting.
Pancreatitis (inflammation of the pancreas) can cause blood and mucus in the stools.
Antibiotic-associated colitis can occur after administration of some antibiotics. It usually is self-limiting and ceases after antibiotic treatment is discontinued.
Blood clotting disorders ("coagulopathies") including clotting problems due to liver failure, some rat poisons, and low platelet count ("thrombocytopenia") can result in blood in the stool and be mistaken for colitis.