Canine Constipation Study Guide

Overview and Clinical Importance

Constipation is defined as the infrequent or difficult evacuation of feces, which are typically dry and hard. This is a common clinical problem in small animal practice that ranges from mild, self-limiting episodes to severe, life-threatening conditions requiring emergency intervention. Understanding the pathophysiology, diagnostic approach, and treatment options is essential for NAVLE success and clinical practice.

Obstipation represents intractable constipation characterized by an inability to evacuate the mass of dry, hard feces, with impaction potentially extending from the rectum to the ileocolic valve. When obstipation results in permanent dilation and hypomotility of the colon, the condition is termed megacolon. While megacolon is more common in cats, it does occur in dogs and carries significant clinical implications.

Pathophysiology

Normal Colonic Function

The colon serves two primary functions: water and electrolyte absorption and fecal storage. Peristaltic waves are responsible for the aboral movement of fecal material in the colon. Giant, migrating waves occur intermittently throughout the day and move material farther and more rapidly, constituting the gastrocolic reflex that is common after meal ingestion.