Constipation in Cats and Dogs

Constipation in Cats and Dogs

Animals Affected

Cats and dogs.


Constipation is a syndrome in which a pet has difficulty defecating or is unable to defecate.   It is characterized by repeated attempts to defecate that produce only small amounts of feces or no feces at all.

Constipation may be triggered by dehydration, abnormally large feces in the colon, neurological irregularities that impede normal defecation, diseases or syndromes that make pets too weak to defecate normally, or masses or foreign objects in the rectum that physically block the pathway of feces.

Mild constipation is uncomfortable for pets and causes repeated straining.  Severe constipation, known as obstipation, can have severe impacts on health and in the worst cases may be fatal.  Constipation is most manageable in the early stages of the syndrome.

Constipation tends to be a recurrent problem in pets. Owners of pets that suffer an episode of constipation should take steps to prevent further episodes in the future.


  • The most common symptom of constipation is repeatedly attempting to defecate while producing only small amounts of feces or no feces whatsoever.
  • Constipated pets may pass small bowel movements that are very hard and dry. The bowel movements may be pellet-like.
  • Constipated animals often go one or more days without producing bowel movements.
  • Pets with severe constipation that has lasted several days may stop eating or  become weak.  Vomiting may occur during attempts to defecate.
  • Severe straining may trigger bleeding from the rectum.  This can lead to spots of blood in the house.
  • Pets may urinate inappropriately (cats, dogs) while straining to defecate.
  • Pets with constipation often have a foul odor, particularly near the anus.

Risk Factors

  • Age is a leading risk factor. Constipation is more common among older cats and dogs.
  • It is suspected that gender is a risk factor, with females suffering higher rates of constipation than males.
  • A hereditary or individual predisposition plays a role in constipation.
  • Pets with diseases such as kidney failure that cause weakness or dehydration are at increased risk of constipation.
  • Pets that miss one or more meals may suffer constipation triggered by the interruption of normal flow through the intestines.
  • Pets that consume foreign objects such as bones or pieces of wood may have those objects lodge in the rectum, making defecation impossible.


Mild constipation is uncomfortable.  Repeated straining may trigger house soiling as pets pass small amounts of urine or feces in abnormal locations.  Heavy straining may lead to rectal prolapse, a serious condition in which rectal tissue passes outside of the anus.

Severe or chronic constipation may suppress consumption of food and water, leading to dehydration, weight loss, weakness, and deterioration of body condition.   In the worst cases, death may occur.


Diagnosis often can be made on the basis of physical examination.  Veterinarians usually perform rectal exams on constipated pets to assess the nature of the feces in the colon and to check for foreign objects or masses in the rectum.  X-rays aid in assessing the degree of constipation and in searching for foreign objects and masses that cannot be located on rectal examination.  Urine tests may be recommended to ensure that a urinary tract infection is not contributing to straining.  Blood tests may be performed to look for diseases such as kidney failure that contribute to constipation.


Mild constipation may respond to administration of fluids to correct dehydration, fiber supplementation to help promote regularity, and oral administration of mild laxatives (Laxatone® or Petromalt®).

Pets with moderate constipation may pass feces after administration of a simple enema.

Severe constipation that does not respond to the above steps may require a procedure known as manual deobstipation.  In this procedure a veterinarian removes feces from the rectum by hand, with the assistance of repeated enemas.  Most pets must be sedated or anesthetized for manual deobstipation.

As a last resort, pets with intractable constipation may require surgical removal of feces from the colon, rectum, and intestines.


Once an episode of constipation has been successfully treated, owners should focus on preventing further episodes, and on rapidly treating any episodes that develop.  Stool production should be monitored carefully, and recurrent episodes of constipation should be treated immediately to prevent the serious complications of severe constipation.

  • Dietary fiber supplementation helps to promote regularity.  High fiber pet foods may be prescribed by a veterinarian to prevent constipation.  Commercial products containing psyllium (similar to Metamucil® in humans) can be added to the diet. Some pets may show improvement if canned pumpkin is added to the diet in small quantities.
  • Regular administration of laxatives such as Laxatone®, Petromalt®, or lactulose may help to prevent further episodes of constipation.
  • If present, diseases such as kidney failure that contribute to constipation should be treated.
  • Commercially available pet enemas can be administered at home in cases of recurrent constipation.  These enemas are messy.  Many people are not willing to administer them to their pets.


Pets with bladder infections may appear to be constipated due to repeatedly straining to pass urine.  For that reason, urine tests may be performed on pets that appear constipated.

Pets that go one day without defecating or that skip one bowel movement often are not constipated.  This is particularly true if they are not noted to be straining to defecate, and if they are eating and behaving normally.  Most pets in this situation will pass feces normally within 24 hours.

Copyright © Eric Barchas, DVM All rights reserved.
The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.