Cat Constipation: Causes, Home Remedies & When to See the Vet

By Sarah Bennett, Certified Animal Nutritionist

Occasional constipation in cats is common and often resolves with simple management at home. However, chronic or severe constipation is a different matter entirely — it can spiral into obstipation (complete inability to defecate) and, over time, irreversible megacolon. Understanding the causes, recognizing when home management is appropriate versus when professional care is urgently needed, and implementing good prevention strategies will keep your cat comfortable and protect their long-term colon health.

Understanding Feline Constipation

Constipation is defined as infrequent, difficult, or incomplete defecation. Normal defecation frequency in cats is roughly once to twice daily, though this varies by individual. Hard, dry feces that the cat strains to pass, or absence of any fecal output for more than 24–36 hours, are the key indicators. The longer feces sit in the colon, the more water is extracted, making them progressively harder and more difficult to pass.

Obstipation refers to severe, refractory constipation where the colon is packed with hard, impacted feces that the cat cannot pass at all, regardless of effort. This is a medical emergency. Megacolon is the end-stage condition where the colon wall loses its contractile function — discussed in a separate article.

Common Causes of Constipation in Cats

Dehydration

By far the most common cause. The colon's primary job is to reabsorb water from waste material. When a cat is chronically dehydrated — which is extremely common in cats eating primarily dry food — the colon extracts even more water from feces, leaving them hard and dry. This is why increasing water intake is the single most impactful intervention for most constipated cats.

Hairballs and Grooming

Cats ingest large amounts of hair during grooming. Hair that accumulates in the colon can compact and impair normal fecal transit. Long-haired breeds are especially susceptible. Regular brushing to reduce ingested hair is an important preventive measure.

Dietary Factors

Low-fiber diets, sudden diet changes, and bone ingestion (from raw diets) are common dietary contributors. Bones can produce hard, chalk-white feces that are difficult to pass. Inadequate dietary fiber reduces the bulk needed to stimulate normal colonic motility.

Litter Box Issues

Cats are fastidious about their toileting environment. A dirty litter box, a box in a stressful location, or discomfort with box type can cause cats to voluntarily suppress defecation — leading to constipation. Multi-cat households with insufficient boxes are a common scenario.

Obesity and Inactivity

Overweight cats and sedentary indoor cats have reduced GI motility. Physical activity stimulates colonic movement; inactive cats are at higher risk.

Orthopedic Pain

Arthritis, hip pain, or other musculoskeletal discomfort can make the squatting position needed for defecation painful. Affected cats may avoid or rush through defecation, leading to incomplete evacuation and constipation. This is an underrecognized cause in older cats.

Pelvic Narrowing

Cats that have suffered pelvic fractures (often from trauma) may have a narrowed pelvic canal through which feces cannot pass normally. Surgical correction is sometimes required.

Neurological Conditions

Conditions affecting spinal cord function — intervertebral disc disease, Manx cat sacral deformity, or trauma — can disrupt the nerve signals that coordinate defecation.

Underlying Disease

Hypothyroidism (rare in cats), CKD (dehydration), hypercalcemia, hypokalemia, and certain medications (opioids, anticholinergics, antacids) can all cause or worsen constipation.

Home Remedies for Mild Constipation

For cats with occasional, mild constipation that are otherwise well, several safe home interventions can be tried:

Increase Water Intake

This is the foundation of management. Switch from dry to wet food, or add water to dry food. Offer a cat water fountain — many cats prefer moving water. Place multiple water bowls around the house in quiet locations away from food and litter boxes. Adding a small amount of low-sodium chicken broth to water can encourage drinking in reluctant cats.

Canned Pumpkin

Plain canned pumpkin (not pie filling — no spices or sugar) is a time-honored home remedy. It contains soluble fiber that absorbs water and helps soften stools. One to two teaspoons mixed into food daily is a typical starting dose. Most cats tolerate it well, and many accept the flavor readily mixed into wet food.

Laxatone and Hairball Remedies

Petroleum-based hairball remedies (Laxatone, Petromalt) act as mild laxatives by lubricating the GI tract and helping hair and compacted material pass more easily. Given a few times per week as preventive, or daily during a constipation episode, they can be effective for mild cases and hairball-related constipation.

Miralax (Polyethylene Glycol 3350)

Many veterinarians now recommend Miralax — an osmotic laxative available over the counter for humans — for cats with mild to moderate constipation. The typical dose is 1/8 to 1/4 teaspoon mixed into wet food once or twice daily, but always confirm dose and frequency with your vet before starting. It is tasteless and odorless, making it easy to administer. Miralax draws water into the colon, softening stools.

Increase Physical Activity

Daily play sessions using wand toys, laser pointers, or puzzle feeders stimulate gut motility and are part of good long-term constipation prevention, especially for indoor cats.

Litter Box Optimization

Clean the litter box at least once daily. Provide one box per cat plus one extra. Ensure the box is large enough for comfortable squatting. Try different litter types if your cat seems reluctant to use the box.

When Is It an Emergency?

Stop home management and seek veterinary care promptly if:

• The cat has produced no feces in 48–72 hours despite home interventions
• The cat is straining repeatedly with no output (this can also indicate a urinary blockage — a separate but equally urgent emergency, especially in male cats)
• There is blood in or around the stool
• The cat is vomiting, lethargic, or showing signs of abdominal pain
• You can feel or see a very hard, distended abdomen
• The cat is a male straining at the litter box — rule out urethral obstruction first, which is life-threatening

Veterinary Treatment

For moderate to severe constipation, your vet may recommend an enema administered under sedation to evacuate the colon. Multiple sessions may be needed for severe impaction. Prescription laxatives — lactulose (an osmotic agent), cisapride (a prokinetic that stimulates colonic muscle contraction), or bisacodyl — may be prescribed for ongoing management. The underlying cause must be identified and addressed to prevent recurrence.

References

1. Washabau RJ, Holt D. "Pathogenesis, diagnosis, and therapy of feline idiopathic megacolon." Veterinary Clinics of North America: Small Animal Practice. 1999;29(2):589-603. PMID: 10202484
2. Freiche V, et al. "Uncontrolled study assessing the impact of a psyllium-enriched extruded dry diet on faecal consistency in cats with constipation." Journal of Feline Medicine and Surgery. 2011;13(12):903-911. PMID: 21856205