Constipation is common in cats, especially seniors. Without management, it can progress to obstipation (severe, intractable constipation) and megacolon (permanent dilation of the colon). Diet is one of the most effective management tools.

What's Considered Constipation

Normal cat defecation: at least once daily, formed but not hard, no straining. Signs of constipation:

  • Less than once daily (or much less)
  • Small, hard, dry stools
  • Visible straining in litter box
  • Crying or discomfort
  • Tiny amounts of stool with much effort
  • Sometimes liquid stool around hard mass (paradoxical diarrhea)

Common Causes

  • Dehydration: Most common cause. Cats are notoriously bad water drinkers, especially on dry food only.
  • Hairballs: Especially in long-haired cats.
  • Diet: Low moisture, low fiber, or excessive bone in raw diets.
  • Lack of exercise: Sedentary cats.
  • Stress: Cats hold stool when stressed.
  • Litter box aversion: Refusing dirty or stressful boxes.
  • Pelvic injuries: Old fractures narrow the pelvic canal.
  • Kidney disease: Causes dehydration.
  • Aging: Reduced colonic motility.
  • Megacolon: End-stage colonic dysfunction.

What to Look For in Food

Wet food emphasis: The single most impactful change. Higher moisture supports proper hydration and stool consistency. Aim for 50-80% of calories from wet food.

Quality fiber: Look for moderate fiber from sources like beet pulp, psyllium, pumpkin. Both soluble and insoluble fiber help.

Quality protein: Maintains GI motility.

Adequate fat: Helps stool slide through. Not high-fat, just adequate.

Prescription Options for Severe Cases

  • Hill's Prescription Diet w/d (high fiber)
  • Royal Canin Gastrointestinal Fiber Response
  • Purina Pro Plan Veterinary OM (moderate fiber)

Beyond Food

Hydration

  • Multiple water sources around the home
  • Water fountains (many cats prefer running water)
  • Wide shallow bowls (some cats avoid touching whiskers)
  • Add water to wet food
  • Bone broth (low sodium, no onion/garlic)

Litter Box Optimization

  • Multiple boxes (one per cat + one extra)
  • Clean daily
  • Quiet locations
  • Avoid covered boxes for older arthritic cats
  • Low-entry boxes for seniors

Supplements & Medications

  • Pumpkin: 1-2 tsp daily of plain canned pumpkin (not pie filling)
  • Miralax (polyethylene glycol): Often vet-recommended, gentle stool softener
  • Lactulose: Prescription stool softener
  • Cisapride: Prescription motility enhancer for severe cases
  • Probiotics: Support gut health

Hairball Management

For long-haired cats, constipation often relates to hairballs:

  • Daily brushing
  • Hairball control food
  • Hairball gel supplements (Laxatone)

What to Avoid

  • Dry-only diets (worsen dehydration)
  • Excessive bone in raw diets
  • Low-fiber foods
  • Ignoring early signs (progression to megacolon is harder to manage)
  • Mineral oil (can be aspirated)

When to See a Vet

  • Constipation lasting more than 2-3 days
  • Severe straining
  • Vomiting
  • Lethargy
  • No appetite
  • Visible distress in litter box

FAQ

Can pumpkin really help?

Yes — the soluble fiber adds bulk and moisture. 1-2 tsp daily mixed into wet food.

How quickly will diet changes help?

Often within 1-2 weeks. Severe cases may need medication alongside diet.

What is megacolon?

End-stage condition where colon permanently dilates and loses motility. Some cats need surgery.

The Bottom Line

Increase wet food, support hydration aggressively, consider fiber supplementation, and address underlying causes. Early intervention prevents progression to megacolon. Browse our cat food rankings.