Constipation in Cats

Causes, Treatment, and Prevention

cat constipation
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What Is Constipation in Cats?

Constipation is a medical term that means difficult or infrequent passage of feces in the colon. This may lead to troublesome bowel movements, including straining and discomfort. For cats, owners may notice fewer stools being passed or even no stool at all. If passed, the stool may be very hard and dry.

The colon is the main area in the gastrointestinal tract for water to be absorbed. When feces are kept in the colon for an extended period of time, the retained feces become firm and dried out. This, in turn, leads to difficulty passing the stool and discomfort.


  • Straining
  • Abdominal pain/crying when defecating
  • Inappetence or vomiting
  • Small amounts of liquid stool or blood

This last sign may be confusing to cat owners. A constipated cat may strain so hard that a small amount of liquid feces or blood may be passed and mistaken for diarrhea. However, this liquid is actually passing around the hard stool, and the cat is constipated.

Causes of Constipation in Cats

Constipation may occur regardless of the cat’s age and health status. Cats are notoriously poor drinkers and, especially when fed a dry kibble diet, they are at higher risk of developing constipation. Any condition that leads to dehydration can also lead to constipation. Being sedentary and overweight are also risk factors. There is a very serious condition that can occur in overweight, middle-aged cats, called megacolon. Other issues that can lead to constipation include:

  • Hairballs or ingestion of foreign material
  • Pelvic pain or pelvic injuries resulting in a narrowed pelvic canal
  • Avoiding the litterbox
  • Breed, especially Manx

Megacolon in cats

Megacolon in cats is the result of serious constipation in cats. It is seen most often in middle-aged male cats that tend to be overweight.

In these cats, the colon loses appropriate nerve function and this results in a stretched-out and weak colon. Because the colon is dilated and much large than normal, feces may back up in the cat to truly astounding proportions. Adding to the issue, the colon lacks the ability to successfully push the feces out.

Megacolon is often diagnosed as a primary condition but may also occur secondary to long-standing and untreated normal constipation. This occurs because the colon becomes distended and weak due to large amounts of feces being trapped inside it over time. This stretching damages both the nerves and muscles of the colon, which affects its ability to contract.

The possibility of chronic constipation turning into megacolon is a serious concern and all constipated cats should be treated aggressively and in a timely manner.

Diagnosing Constipation in Cats

Any cat suspected of being constipated should see its veterinarian as soon as possible. The veterinarian will take a thorough history of what has been happening at home and do a complete physical exam.

A constipated cat will often have an enlarged colon full of hard fecal matter that the veterinarian can palpate. This may not be possible in overweight cats, so a quick and non-invasive x-ray will show the extent of the constipation and how dilated the cat’s colon may be.

X-rays will also be used to try to identify any physical causes of the constipation such as a foreign body obstruction, pelvic or sacral injuries, spinal issues, or tumors. In some cases, a more detailed look with an abdominal ultrasound may be necessary.

Treatment for Constipation in Cats

After the cause of the constipation is found, a treatment plan will be formulated with your veterinarian. Typically, constipated cats will require enemas and intravenous fluids. Miralax or another laxative may be added to help soften the feces enough to allow the cat to pass them.

If laxatives, enemas, and rehydration with fluid therapy do not enable the cat to defecate, manual extraction of the hardened feces by a veterinarian may be required. This procedure is performed under general anesthesia.

If a cat’s constipation recurs or becomes a long-term problem, dietary management or medications may be needed to prevent a recurrence. There are prescription diets, both in kibble and canned form, that may aid the cat in passing softer stool. Oral laxatives may also be administered at home and may work to soften the stool and encourage the cat to defecate.

In cats with severe cases of megacolon, your veterinarian may prescribe pro-motility agents to aid the cat’s colon in contracting and propelling feces out of the rectum. It is essential to keep up with your cat’s bowel movements to avoid more serious complications. Encouraging the cat to drink as much as possible or adding water to its food may also help ease its constipation issues.

Some cats may become constipated if their litter box is left dirty, and they do not feel comfortable defecating in it. Other cats in the house that may be guarding the litter box or attacking the constipated cat while they are in the box can also be an issue. It is important to have one litter box per cat plus an additional in your home. This will ensure there is always a litter box for your cat to use so that it will not willfully abstain from defecating.

If your cat has long hair and frequent hairballs that are contributing to its constipation, there are diets and supplements that can help the hair pass more easily through the gastrointestinal tract. Frequent brushing to remove as much of the hair as possible, before the cat can ingest it via grooming, can help tremendously to reduce hairballs.

Prognosis for Constipation in Cats

The majority of constipated cats respond to fluids, enemas, and medication or manual removal of stool. Surgery as a treatment for constipation in cats is rare but possibly necessary. Tumors or foreign bodies may need to be removed from the colon surgically. Also, in cases of megacolon that are refractory to traditional treatments, surgery may be recommended.

Surgical correction of severe and refractory megacolon involves removal of the affected portion of the colon, in a procedure called a partial or subtotal colectomy. Cats may have chronic diarrhea or fecal incontinence after this surgery, but the overall prognosis is good.

Constipation in cats is common and, in most cases, is easily treated. You should pay attention and learn the normal frequency of defecation for your cat to enable you to notice if there is an issue.

Typically, most cats will have a bowel movement every day to every other day. If you notice your cat is suddenly not defecating normally or is straining in the litter box, you should make an appointment with its veterinarian right away. Prompt treatment of constipation in cats can avoid future more serious complications.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Article Sources
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  1. Constipation. Cornell College of Veterinary Medicine.

  2. Constipation in Cats. VCA Animal Hospitals.

  3. Constipation and Megacolon in Cats and Dogs. Veterinary Information Network.