Constipation is one of the most common digestive problems in cats -- and if left untreated, can progress to megacolon, a serious condition where the colon becomes permanently stretched and unable to function. Early intervention prevents this progression.
Normal vs Abnormal
- Normal: Most cats defecate once daily. Stools should be formed, moist, easy to pass.
- Constipation: Infrequent (every 2-3+ days), hard, dry, small stools with straining.
- Obstipation: Severe constipation -- complete inability to pass stool. Medical emergency.
- Megacolon: Chronically dilated, weakened colon that has lost the ability to contract. End-stage.
Causes
- Dehydration: The #1 cause -- body pulls water from stool when dehydrated
- Low fiber diet: Insufficient bulk to stimulate peristalsis
- Obesity: Abdominal fat compresses the colon
- Pain: Arthritis makes posturing in litter box painful, cat avoids defecating
- Pelvic injury: Old fractures can narrow the pelvic canal
- Neurological: Nerve damage affecting colon motility
- Idiopathic megacolon: Unknown cause -- colon simply stops working
Treatment Ladder
| Stage | Treatment |
|---|---|
| Mild | Increase water intake (wet food, fountains), add fiber (pumpkin, psyllium), increase exercise |
| Moderate | Stool softeners (Miralax 1/8-1/4 tsp daily), lactulose (prescription), diet change |
| Severe | Enemas (vet-administered only), manual deobstipation under anesthesia |
| Megacolon | Prokinetic drugs (cisapride), and if unresponsive: subtotal colectomy (surgical removal of most of colon) |
Miralax for Cats
- Polyethylene glycol 3350 (PEG) -- osmotic laxative
- Commonly recommended by vets at 1/8-1/4 teaspoon mixed into wet food once or twice daily
- Draws water into the colon to soften stool
- Generally safe for long-term use under veterinary guidance
- Unflavored -- mixes easily into wet food
Prevention
- Wet food: The single most effective prevention
- Multiple water stations: Water fountains increase intake
- Fiber: 1-2 tsp canned pumpkin daily
- Weight management: Reduce abdominal fat
- Pain management: Treat arthritis so cat is comfortable posturing
- Clean litter boxes: Dirty boxes make cats hold it longer
Frequently Asked Questions
Can cats die from constipation?
Yes, in extreme cases. Severe obstipation can cause: electrolyte imbalances (life-threatening), colonic perforation (fecal peritonitis -- surgical emergency), and systemic toxicity from waste product buildup. Megacolon that does not respond to medical management requires surgery (subtotal colectomy). Most cats do well after surgery, though stools are permanently soft. The key is not letting constipation reach these extremes -- early dietary intervention and veterinary care prevent progression.
