Constipation in Cats
This client information sheet is based on material written by Ernest E. Ward Jr., DVM.
© Copyright 2002 Lifelearn Inc. Used with permission under license. September 30, 2009.
Cambridge VetCare
Animal Clinic, PA
Cambridge, MN

Constipation can be defined as an abnormal accumulation of feces resulting in difficult bowel movements.  This may result in reduced
frequency or absence of defecation.  The feces are retained in the large intestine or colon.  Since one of the functions of the colon is water
absorption the retained feces become hard and dry, which makes fecal passage even more difficult.  Constipated cats strain in an attempt to
defecate resulting in abdominal pain.  Some constipated cats may pass small amounts of liquid feces or blood.

What causes constipation?

Factors associated with causing constipation include:

  • Hairballs, especially in long-haired cats
  • Ingestion of foreign bodies
  • Obstruction caused by tumors, strictures or masses compressing or blocking the large intestine
  • Injures resulting in a narrowed pelvic canal
  • Damage of the nerves, which cause the colon to contract.  This may develop after trauma or may be part of a more generalized
    neurological disease.

In some cases, there is no obvious cause identified.  Constipation is a condition seen most commonly in middle-aged and older cats.  

What is megacolon?

This term refers to a dilated and weak colon that causes sever constipation.  Megacolon may be seen as a primary entity or following long-term
constipation.  When the colon becomes distended with fecal material over a prolonged period of time, its ability to contract may be reduced or
lost resulting in megacolon.

How are constipation and megacolon diagnosed?

In most cases, a diagnosis of constipation can be made on the basis of the cats clinical signs.  Affected cats usually strain unsuccessfully to
defecate and may cry in pain.  Any feces passed are hard and dry.  The cat may also show signs of lethargy, reluctance to eat and vomiting.  
Further tests may be needed in order to diagnose the cause of the constipation and these may include abdominal and pelvic x-rays to look for
pelvic injuries, colonic strictures or tumors.  X-rays are also the primary test for the diagnosis of megacolon.  

How can constipation and megacolon be treated?

Treatment varies depending on the cause of constipation.  If an obstruction such as a colonic tumor is present, surgical treatment may be
performed.  Initial treatment of a cat with constipation may involve administration of enemas and manual extraction of feces by a veterinarian.  
The latter may necessitate an anesthetic or sedative.  Treatment of dehydration with intravenous fluids may also be needed in cats that have
become dehydrated.  If the constipation recurs or becomes a long-term problem, continuous therapy may be needed to prevent recurrence.   

A wide variety of treatments are available to soften the feces and promote regular bowel movements.  High fiber diets may be helpful and
lubricating laxatives or stool softeners may also be used in mildly affected cats.  Those more severely affected may need drugs that stimulate
contraction of the colon.  The doses of all of these drugs may need to be altered to produce the desired effect.  Ideally, cats should defecate
at least once every other day.  Over a period of time, resistance to the treatment may be found necessitating an increase in the drug dosage or
a change in therapy.  No changes to the treatment protocol should be made without consulting your veterinarian.  

In long-haired cats, regular grooming and hairball removal agents and diets may reduce hair ingestion and the likelihood of hairballs causing
constipation.  It is important to ensure that there is always access to a clean litter tray so that frequent defecation is encouraged.  If megacolon
develops or if the constipation is severe and medical treatment is unsuccessful, surgery may be recommended.  Surgical treatment involves
removal of most of the colon called a partial or sub-total colectomy.  Most cats do very well with few side effects following this surgery.

What is the long-term outlook for a cat with this problem?

The long-term outlook varies according to the cause of the constipation; however, most cats can be adequately managed without surgery and
resume normal, healthy lives.