Constipation in Cats – Causes, Symptoms and Treatment

Causes      Symptoms       Diagnosis      Treatment      Home treatment      Prevention

constipation in cats

What is constipation?

Constipation is the infrequent passage of hard and dry stools. There is no set number of bowel movements a cat must take in a day, but one to two is average. Constipation can affect cats of any age although it is seen more commonly in middle-aged to elderly cats.

Chronic constipation can lead to a condition known as megacolon, in which the colon becomes abnormally dilated and enlarged and loses its ability to contract. This may ultimately lead to obstipation, which is a complete blockage.


  • Dehydration: One of the most common causes of constipation in cats is due to dehydration. Water is reabsorbed from the colon and if the cat is dehydrated, the body will try to conserve water by removing additional water from the stool.
  • Reluctance to defecate: Dirty litter trays, not wanting to share a litter tray, incorrect placement of a litter tray or go outside (if it’s raining or cold).
  • Obstruction of the colon: Birth defects, hairballs, cancer, polyps or a foreign object.
  • Dietary: Diets which are low in fibre or eating food which contains hair and bones.
  • Drugs and medications: Antihistamines, diuretics, painkillers, and antibiotics can cause constipation in the cat.
  • Painful defecation: Causes include impacted anal glands or perianal bite abscess.
  • Neurological: Including damage to the nerves in the colon and anus, Manx syndrome, spinal cord injury, paralysis.
  • Hypothyroidism: A condition in which the thyroid gland doesn’t produce enough thyroid hormone which slows down metabolism. Hypothyroidism is rare in cats.
  • Pelvic injuries: Car accidents or trauma which lead to fractures narrowing the pelvic canal.
  • Metabolic/hormonal: Low potassium (hypokalemia), kidney failure, diseases of the thyroid and parathyroid glands.
  • Idiopathic. Sometimes it is not possible to find a cause of constipation.


As one would expect, the most obvious sign of constipation is straining in the litter tray. After a period of straining, the cat may pass small hard/dry feces and may cry in pain as he attempts to defecate.

As the condition progresses other symptoms may include:

Important: Another common and more serious cause of straining in the litter tray is a urinary blockage. This condition is seen more often in male cats due to their narrower urethra.

A urinary blockage is a life-threatening medical emergency and requires immediate treatment.


Your veterinarian will perform a physical examination of your cat and obtain a medical history from you. The exam will reveal a hard and full colon.

Diagnostic tests:

Routine serum biochemical profile, complete blood count, and urinalysis to check for underlying systemic disorders such as kidney disease or diabetes mellitus which could cause dehydration and electrolyte imbalances.

X-ray of the abdomen and pelvis to assess the size of the colon and to determine the extent of impaction as well as to check for foreign objects.

If cancer is suspected, colonoscopy and biopsy may be performed.


Mild cases of constipation without accompanying symptoms such as vomiting or depression may be treated on an outpatient basis at home by giving your cat extra fibre or stool softeners.

More severe cases may require an enema or manual extraction of the feces.

Rehydration with intravenous fluids and prevention of future dehydration.

If possible, find and remove the cause of constipation such as:

  • Litter trays: Make sure there are enough litter trays in the house. One per cat, plus one extra. Scoop solids twice a day and completely empty once a week.
  • Cancer: Surgical removal of tumours and/or chemotherapy/radiotherapy.
  • Blockage: Surgery to remove any blockages and/or increasing fibre, giving stool softeners to assist with defecation.
  • Dietary: Feeding a high fibre diet.
  • Drugs or medications: If possible, stopping any medications or adding extra fibre to the diet while the cat is on the drugs.
  • Anal glands/abscess: Treating abscess or impacted anal glands by emptying, applying antiseptic/antibiotics to the area and oral antibiotics.
  • Hypothyroidism:  Hormone replacement therapy (thyroxine).
  • Low potassium: Oral or intravenous potassium replacement.
  • Kidney disease: Dietary management with a low protein diet, phosphorous binders, and supportive care.

Home treatment: 

Adding bulk to the diet can assist in mild cases of constipation such as unprocessed wheat bran or Metamucil. Add approximately 4 teaspoons of unprocessed wheat bran or Metamucil per 475g canned food.

Pumpkin is also a good way to prevent constipation occurring as it is high in fibre and has a high water content, both of which help to keep bowel movements regular.  Add 1-2 teaspoons of canned or cooked pumpkin to your cat’s daily meal.

Laxatone is a petroleum gel which helps to lubricate the digestive tract.

Increase water consumption, which may include feeding more wet food, such as canned or raw meat as well as adding additional water bowls or investing in a cat water fountain.


Removing the cause if at all possible is the best course of action, which includes:

  • If your cat is prone to hairballs, speak to your veterinarian about hairball diets or treatments.
  • Frequent brushing to remove loose hair from the coat.
  • Regular treatment of parasites.
  • Add fibre such as pumpkin or flax seeds to the diet.
  • Provide access to clean, fresh drinking water at all times.
  • Increase water consumption by switching your cat to a wet diet and encouraging him to drink more.
  • Keep your cat’s weight down.
  • Ensure your cat gets plenty of exercise with interactive toys.