PAPER Long-term results of subtotal colectomy for acquired hypertrophic megacolon in eight dogs OBJECTIVES: To evaluate the long-term results of subtotal colectomy for acquired hypertrophic megacolon in the dog. METHODS: Eight dogs with acquired hypertrophic megacolon underwent subtotal colectomy with preservation of the ileocolic junction. Long-term follow-up was obtained by clinical records and telephone interviews with the owners. RESULTS: Eight large-breed dogs (age range: 6 to 12 years; mean age: 10  75 years) were enrolled. The use of bone meal, low levels of exercise, chronic constipation with dyschesia and tenesmus refractory to medical management were factors predisposing dogs to acquired hypertrophic megacolon. The diagnosis was confirmed in all animals by abdominal palpation, plain radiography and postoperative histopathological findings. There were no intraoperative complications. One dog died as a result of septic peritonitis. The clinical conditions (that is, resolution of obstipation and stool consistency) of the remaining seven dogs were improved at discharge; all animals returned to normal defecation in five to 10 weeks (mean: 7  3 weeks) and were alive 11 to 48 months (mean: 40  5 months) after surgery. CLINICAL SIGNIFICANCE: Predominantly bony diet and/or low levels of physical activity may predispose dogs to acquired hypertrophic megacolon. Our results emphasise the long-term effectiveness of subtotal colectomy with preservation of the ileocolic junction in this condition. T. NEMETH, N. SOLYMOSI AND G. BALKA* Journal of Small Animal Practice (2008) 49, 618–624 DOI: 10.1111/j.1748-5827.2008.00624.x INTRODUCTION Megacolon is characterised by the presence of an enlarged, hypomotile colon. This condition has been reported to occur in human beings (Swenson and Bill 1948), cats (Dietzmann 1968), dogs (Bright and others 1986) and pigs (Bassett and others 1999). In human beings, congenital megacolon (Hirschsprung’s disease) is caused by the failed migration of colonic ganglion cells during gestation. Varying lengths of the distal colon are unable to relax, causing functional colonic obstruction (Ehrenpreis 1970). Acquired megacolon may result from long-standing mechanical or functional bowel obstruction and may be classified as either primary or secondary. In cats, the causes and treatment of primary idio- pathic megacolon have received consider- able attention (Bright and others 1986, Rosin and others 1988, Bertoy and MacCoy 1989, Barreau 1994, Washabau and Hasler 1997, Washabau and Holt 1999). Specifically, it has been proposed that secondary megacolon can develop as a result of chronic obstructive lesions (for example pelvic canal stenosis) affecting the colon (Holt and Brockman 2003). Alternatively, this condition may be caused by neurological abnormalities resulting from sacral nerve injury or sacral spinal cord deformity (MacPhail 2002). Al- though canine-acquired megacolon has been described previously (Sahay and others 1983, Bright and others 1986, Barreau 1994, Petrus and others 2001), data concerning the long-term clinical out- come of this condition remain scanty. Nonetheless, medical (Hall and Washabau 1997, Hasler and Washabau 1997) and surgical strategies for the treatment of feline and canine megacolon have been de- scribed. Specifically, subtotal or total colec- tomy has been advocated as the treatment of choice in cases non-responsive to med- ical therapy (Fellenbaum 1978, Bright and others 1986, Bertoy and MacCoy 1989, De Haan and others 1992, Barreau 1994). In this case series, we sought to evaluate the long-term results of subtotal colectomy for acquired hypertrophic megacolon in the dog. We therefore reviewed the clinical data of eight dogs treated by this technique during a 5-year period. MATERIALS AND METHODS A total of eight dogs were included in the study. All animals had a history of bony diet, low levels of exercise, chronic Department and Clinic of Surgery and Ophthalmology, *Department of Pathology and Forensic Veterinary Medicine, Faculty of Veterinary Science, Szent Istva ´n University, Budapest, Hungary 618 Journal of Small Animal Practice  Vol 49  December 2008  Ó 2008 British Small Animal Veterinary Association