November 10, 2011 Dr. Washabau’s research in the mid-1990s through the early 2000s was instrumental in better understanding the pathogenesis of and defining therapy for cats with idiopathic megacolon.1-3 Many cats have one or two episodes of constipation without further recurrence, although others progress to complete colonic failure. Middle-aged male cats (mean, 5.8 years) are particularly at risk for the clinical continuum of constipation, obstipation, and dilated megacolon. The majority of cases (~ 62%) are defined as idiopathic megacolon, while pelvic canal stenosis (~ 23%) and nerve injury (~11) are minor causes in the development of this syndrome.4 In most affected cats, the underlying pathogenesis appears to involve colonic smooth muscle dysfunction.2,3,5 In this group of cats, it is not clear whether this disorder represents a primary or secondary (resulting from long-standing constipation and colonic distension) abnormality. Many cats with mild to moderate constipation respond to conservative medical management (e.g., dietary fiber supplementation, emollient or hyperosmotic laxatives, colonic prokinetic agents). Early use of colonic prokinetic agents (e.g., cisapride) is likely to prevent the progression of constipation to obstipation and dilated megacolon in many cats.5 Some cats may become refractory to these therapies, and progress through moderate or recurrent constipation to obstipation and dilated megacolon. These cats eventually require subtotal colectomy. Cats have a generally favorable prognosis for recovery following subtotal colectomy, although mild to moderate diarrhea may persist for 4 to 6 weeks postoperatively in some cases.Funding for research was supported by grants from various organizations including the American Association of Feline Practitioners 1,5, Morris Animal Foundation 1,2,3, Robert Winn Foundation 1,3,5 , Academy of Feline Medicine 1, American Veterinary Medical Foundation1, and the National Institute of Health3.References: