Constipation in dogs and cats

Constipation (the infrequent and difficult evacuation of feces) and obstipation (intractable constipation) have several causes. The initial use of symptomatic therapy is often successful, but it is preferable to look for causes, because some problems that are initially treatable may become irreversible if symptomatic therapy masks the signs for too long.

A search of the history for iatrogenic, dietary, environmental, or behavioral causes should be done. Feces should be examined to determine whether they contain plastic, bones, hair, popcorn, or other such material. Physical and rectal examinations are done to search for rectal obstruction or infiltration.

Plain pelvic, radiographs can help show whether the animal has anatomic abnormalities or a previously undetected colonic obstruction (e.g., prostatomegaly, enlarged sublumbar lymph node.) Ultrasonography is the preferred technique when looking for infiltrates. Serum biochemistry panel, and urinalysis may reveal causes of colonic inertia.

Colonoscopy is indicated if one suspects an obstruction too orad to be detected by digital examination. Ultrasound-guided fine-needle aspiration of infiltrative colonic lesions sometimes yields diagnostic findings, but colonoscopy (especially rigid) allows a more reliable biopsy specimen to be obtained. If a thorough diagnostic work-up fails to identify a cause in a patient with a grossly dilated colon, then idiopathic megacolon may be present.