MEGACOLON

WHAT IS MEGACOLON?

The term megacolon refers to a very distended, flaccid colon due to a pathology associated with its neuro-muscular function.  This condition is most commonly seen in cats due to a suspected neurologic or muscular dysfunction of the colon (idiopathic), however other cause such trauma, tumors, and hernias can impede the colon to empty feces. From the severe distension of the colon, the patient becomes constipated, and as result he or she is unable to defecate.

HOW DO I KNOW THAT MY DOG HAS MEGACOLON?

Patients with megacolon usually experience clinical signs associated with constipation (straining to defecate, large firm stool, and large palpable colon).  Additional signs associated with megacolon are painful belly, lethargy and decreased to no appetite.

HOW IS MEGACOLON DIAGNOSED?

The diagnosis of megacolon can be made on physical examination by the veterinarian (large colon filled with feces during belly palpation), as well as x rays of the belly. If the cause of the enlarged colon is not found, the diagnosis is likely idiopathic (unknown) by exclusion.

WHAT IS THE TREATMENT OF MEGACOLON?

The treatment of megacolon can be divided into medical (special diet, stool softener, colon motility stimulant and enemas) and surgical (removal of the colon). Special diet should be recommended such as low residue (easily digestible) and avoid high fiber diet. Enemas as usually given to cats after being properly hydrated (IV fluids), and the feces removed manually by the veterinarian under general anesthesia. Please do not use enemas over the counter for cats, because they could be toxic. Laxatives such as lactulose, and motility stimulant (cisapride) should be considered in the first phase of treatment. Unfortunately, cats with megacolon become refractory to treatment and the patient will eventually need surgery.

The surgical treatment for megacolon is the removal of the colon, and the two intestinal ends are sutured together.  Additionally, if there is an obstruction of the pelvic canal due to trauma, the segment of the pelvis can be also removed (pelvectomy).

WHAT ARE THE COMPLICATIONS WITH MEGACOLON SURGERY?

Complications reported with megacolon include infections (sepsis), recurrence of megacolon (residual colon left behind), and abnormal stool consistency. The risk of infection is decreased by providing antibiotic treatment before, during and after surgery. Recurrence of the megacolon is very rare, and it is due to the residual segment of colon not removed the first time. This condition is rarely treated with a second surgery, and most often managed medically (diet, lactulose, cisapride).

WHAT IS THE PROGNOSIS WITH MEGACOLON?

The prognosis with megacolon is excellent, despite temporary diarrhea for the first 2 to 4 months’ post operatively. The diarrhea eventually resolves, and the feces become more firm as the remaining portion of the intestine adapt to the loss of colon.