Megacolon and Obstipation in Dogs

Megacolon is a relatively uncommon intestinal disorder of dogs characterized by Obstipation. Megacolon and Obstipation in dogs can cause a blockage of feces and it is most common in middle aged dogs with geriatric issues. Medically, this disease is touted as a hard extrication of feces from the animal’s colon or large intestine.

Megacolon in itself is a term used to describe a very dilated, flaccid, incompetent colon. This usually occurs, secondary to chronic constipation and retention of feces, but may be a congenital dysfunction. Dogs with congenital megacolon are born with an abnormal lack of normal smooth muscle function of the colon.

Megacolon itself is not a specific disease entity, but it will usually result in obstipation (inability to defecate), since feces is retained in the colon in a larger diameter than is able to pass through the pelvis. The feces also become very dry and hard, as the colon absorbs water. Surgery may be required to treat this condition once medical management has been exhausted.

One of the symptoms listed below should lead you to seek veterinary assistance. Once your pet is in the care of the veterinarian, a physical examination and treatment will be done.

Symptoms of Megacolon and Obstipation in Dogs

The first sign of trouble in these cases usually manifests as simple constipation. Constipation will often be readily identified by owners who routinely monitor their pets’ elimination habits. Observant owners may note one of the following signs:

• Straining to defecate (remaining in a hunched position for longer than usual and exerting repeated abdominal effort)
• Production of less stool than normal
• Production of harder and/or drier stool than normal
• Defecating indoors
• Passing small amounts of liquid stool (with or without mucus and/or blood) intermittently with firm stools intermixed
• Lack of appetite
• Vomiting
• Depression/lethargy
• Weight loss
• Dehydration
• Vomiting

Causes of Megacolon and Obstipation in Dogs

In dogs, diet is the most important local factor affecting colonic function and the quality of feces formed in the colon. As well, ileal distension appears to play a role in the initiating cascade of reflex colonic relaxation and distension in the dog.

Large-breed dogs appear predisposed, and other factors may aggravate the condition such as:

• Dietary bone meal, dietary calcium supplements
• Inactivity
• Chronic constipation
• Autonomic ganglioneuritis
• Pelvic injury
• Tumor

Treatment

Most patients affected with megacolon and Obstipation will need to be hospitalized for initial fluid therapy. This is to rehydrate the body and to correct electrolyte imbalances.

The colon can then be gently evacuated. Your veterinarian will administer anesthesia to your dog, and then manually inject warm water enemas and water-soluble jelly. This will allow for the easy extraction of feces with a gloved finger or sponged forceps.

If the problem is recurrent or especially severe, and is not responding to medical management, surgery may be necessary to repair the colon. Most dog can be cured of recurrent megacolon after undergoing subtotal colectomy surgery.