Constipation in cats is most common in middle-aged and older cats.  It can result from a variety of causes, including hairballs (especially in long-haired cats), ingested foreign bodies such as sticks, colon cancer, or pelvic or anal injuries that narrow the canal through which the feces must pass.  Some cats simply refuse to use a dirty litterbox.  In some cases, no obvious cause is ever identified.

Before passing out of the body, feces are stored within the colon, which is the last part of the large intestine at the end of the digestive tract.  One of the major functions of the colon is to reabsorb water from the fecal material as it passes through.  In constipation, the fecal material remains in the colon too long, and too much water is removed.  This makes the fecal material hard, and bowel movements difficult.  If fecal material accumulates for an even longer time, it can distend and weaken the colon, resulting in a serious condition called megacolon.  In megacolon, the distended bowel loses its ability to contract properly, leading to extremely severe and painful constipation.

Cats with constipation have fewer bowel movements than normal, and they may even stop having them altogether. Constipated cats typically strain while squatting in the litterbox and may howl from abdominal pain.  It is important to distinguish this straining from straining that is caused by a blockage of the urinary tract, a very serious condition seen especially in male cats.  Some constipated cats dribble small amounts of loose or blood-tinged feces.  Constipated cats can also be listless or reluctant to eat.  The abdomen may be distended or tender.

In most cases, your veterinarian will be able to make a diagnosis of constipation based on the history, signs, and physical examination.  However, x-rays may be needed to look for a cause of the problem, as well as to check for megacolon.

Initial treatment of constipation in cats usually involves enemas to remove feces that have built up in the colon.  Sometimes, the vet needs to extract the fecal material manually, a procedure that often requires a sedative or anesthesia.  Intravenous fluids may be needed to correct dehydration caused by the reduced intake of food and water.  Any identified underlying cause should also be treated.  If the problem is severe or chronic, your cat may need medications that stimulate the colon to contract.  Surgery can be required in cases of megacolon.

Long-term problems may require repeated or continual therapy with enemas and various types of laxatives such as stool softeners.  High-fiber diets are also helpful.  Long-haired cats should be groomed regularly and may periodically need medications that help hairballs pass through the digestive system.  It is also important to ensure that cats always have access to a clean litterbox that is located in a quiet, secluded area.

Q&A

How do cats become constipated?

Constipation can result from a variety of causes, including hairballs (especially in long-haired cats), ingested foreign bodies such as sticks, colon cancer, or pelvic or anal injuries that narrow the canal through which the feces must pass.  Some cats simply refuse to use a dirty litterbox. 

What is megacolon?

Megacolon is a serious complication caused by long-term constipation.  The chronically distended bowel loses its ability to contract properly, leading to extremely severe and painful constipation.

Can constipation be confused with other serious conditions?

Constipated cats typically strain while squatting in the litterbox and may howl from abdominal pain.  It is important to distinguish this straining and pain from that caused by a blockage of the urinary tract, a very serious and life-threatening condition seen especially in male cats. 

How is constipation in cats treated?

Initial treatment involves enemas and other methods of manually removing stool for the colon.  Cats with chronic problem may require repeated enemas, long-term stool softeners, and (possibly) drugs that stimulate the muscles of the colon.

Written and reviewed by John A. Bukowski, DVM, MPH, PhD
and Susan E. Aiello, DVM, ELS