WestVet Boise Emergency: 208.375.1600 | WestVet Idaho Falls Emergency: 208.552.0662


Megacolon is the term used for an abnormally enlarged colon. It is often associated with severe constipation.

Megacolon occurs if there is a mechanical obstruction, congenital dysfunction, metabolic disease, nerve damage, or certain endocrine maladies.

Continued water absorption from feces retained in the colon results in constipation. Prolonged colonic distention eventually causes damage to the muscle and nerves, this leads to colonic inertia (lack of contractions).

While most commonly diagnosed in middle-aged and older cats, the Manx remains more predisposed. Common clinical symptoms include:

  • constipation with anorexia
  • vomiting
  • weight loss
  • straining to defecate

Megacolon Veterinary Surgery

Radiographs are used to evaluate for pelvic fractures, malunions, obstructions, and spinal malformations.  Our specialty team utilizes medical management first with stool softeners, enemas, manual evacuation, antibiotics, high fiber diets, and/or prokinetic drugs.
Surgery is indicated if obstipation is recurrent despite adequate medical management. It entails removing the majority of the colon. Megacolon that occurs secondary to a pelvic malunion may require a subtotal colectomy with a pelvic reconstruction.

After veterinary surgery at WestVet

Patients remain hospitalized on IV fluids for 2-3 days post-surgery to ensure adequate hydration; antibiotics and pain medications are administered until the patient’s first stool passes. Tarry diarrhea is expected after surgery, but for 80% of cats over the following 6 weeks, this will more of a soft formed stool. Cats remain continent. Defecation increases by 30-50% and in rare cases, diarrhea persists.

Complications are rare but may include:

  • dehiscence (falling apart of the colonic anastomosis site)
  • leakage of fecal material into the abdominal cavity
  • stricture at the surgery site
  • abscess formation
  • persistence of diarrhea
  • recurrent constipation
  • need for additional surgery

Despite these risks, the prognosis with surgery, in general, is good to excellent in cats. The board certified surgeons at WestVet have extensive training and experience with Megacolon surgical procedures.calico_cat

Please see your family veterinarian for a referral for a consultation with a WestVet surgeon. If you have questions regarding the surgery for Megacolon, feel to contact us with any questions. 208.375.1600.

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