Megacolon secondary to pelvic trauma in a domestic shorthair cat

Abstract

A 6 year old castrated male domestic shorthair cat presented to the Emergency Service at Cornell University Hospital for Animals on June 28, 2010 for obstipation. The patient had been found on the side of the road in 2007 and taken to an animal shelter, where a pelvic fracture was diagnosed by physical exam, but no treatment was undertaken. After his adoption in 2008, the patient had frequent episodes of constipation progressing to obstipation, requiring enemas and manual de-obstipation by his veterinarian. After medical therapy with lactulose and cisapride failed to prevent obstipation, the patient underwent a pelvic osteotomy at CUHA in March 2010, which widened the pelvic canal by approximately 8mm. After surgery, the patient initially defecated on his own, but eventually became obstipated again. After seeing his veterinarian several times for de-obstipation, the cat was sent to CUHA through the emergency service for surgical intervention. Upon presentation, the patient was bright and alert, and slightly overconditioned (BCS 6/9). He was mildly dehydrated, based on skin tent and tacky mucous membranes. A left parasternal heart murmur (grade I/VI) was ausculted. On abdominal palpation, the colon felt distended and filled with firm fecal material; abdominal radiographs supported the physical exam findings. The patient was diagnosed with obstipation secondary to megacolon. The patient was rehydrated with IV fluids and administered three enemas over the next day, and passed a large amount of semi-formed stool the following morning. He was discharged to the care of his owners and scheduled for surgery the following week. On July 7, the patient returned to CUHA and underwent a subtotal colectomy to remove the distended colon. Megacolon is the most common cause of obstipation in cats and can occur secondary to pelvic canal stenosis. The obstructed colon initially becomes hypertrophied, and if the obstruction is not relieved early (e.g., with pelvic osteotomy), the lesion progresses to dilated megacolon, which is a permanent loss of colonic structure and function. At this stage, the colon is no longer responsive to medical treatment and surgical intervention is required. The prognosis for cats with subtotal colectomy is good to excellent, compared to fair to guarded for medical treatment alone.