Constipation is the most common reason, and it usually means dehydration or a blockage in the digestive tract
When a cat stops pooping normally, constipation is almost always the cause. A constipated cat may strain in the litter box, produce small hard stools, or stop going altogether. The most frequent culprits are dehydration (cats naturally drink less water than they should), low-fiber diet, hairballs, or an actual blockage from swallowed objects or matted fur.
Less often, the problem is a medical condition like megacolon (an enlarged colon that loses muscle tone), thyroid disease, or nerve damage. Pain from arthritis or anal gland problems can also make a cat reluctant to use the box. The key is that constipation that lasts more than a day or two, or that happens repeatedly, needs veterinary attention—not because it is always serious, but because a vet can rule out blockages and other conditions that do require treatment.
Key Takeaways
- Constipation caused by dehydration or low fiber often improves with more water intake and dietary changes, but straining that lasts more than two days warrants a vet visit.
- A complete blockage—from a foreign object, severe hairball, or twisted intestine—is a medical emergency and causes vomiting, lethargy, and abdominal pain alongside lack of stool.
- Hairballs are normal in cats but excessive straining or no stool production means the hairball is stuck and needs professional removal.
- Litter box avoidance can look like constipation; if your cat is straining but producing stool, or if the box is dirty or in a stressful location, the issue may be behavioral rather than digestive.
How to tell the difference between constipation and a blockage
A constipated cat will strain in the litter box but usually still produce some stool, even if it is small or hard. The cat may visit the box more often than usual and seem uncomfortable, but remains alert and eats normally. This is uncomfortable but not an emergency.
A blocked cat shows different signs: repeated vomiting, loss of appetite, lethargy, abdominal pain (the cat hunches or cries when touched on the belly), and little to no stool output. A complete blockage is a surgical emergency. If your cat is vomiting and has not pooped in more than 24 hours, or if you see any of these warning signs, call your vet when ready—do not wait to see if it resolves on its own.
Dehydration and diet changes that help mild constipation
Cats are poor drinkers by nature; they evolved to get most of their water from prey. A diet of only dry kibble can leave a cat chronically dehydrated, which hardens stool and makes bowel movements difficult. The fastest way to increase water intake is to switch to wet food (canned or fresh) or add water to dry food until it becomes a paste. Some cats also drink more from a running water fountain than from a still bowl.
Fiber can help, but only if constipation is mild and not caused by a blockage. Adding a small amount of canned pumpkin (plain, not pie filling) or a vet-approved fiber supplement to food sometimes softens stool and encourages movement. Start with a teaspoon mixed into food once daily. If your cat has not pooped in more than two days, or if adding fiber makes straining worse, stop and contact your vet instead.
When hairballs are the problem
Cats groom themselves constantly and swallow loose hair. Most of the time, hair passes through the digestive tract without issue. But long-haired cats, or cats that groom excessively due to stress or skin irritation, can accumulate hair in the stomach or intestines. A hairball that is stuck will cause straining, vomiting, or no stool output at all.
If your cat is a long-haired breed or sheds heavily, regular brushing (several times a week) removes loose hair before it is swallowed. A hairball remedy—a petroleum-based gel that helps hair move through the digestive tract—can be given weekly as prevention. If your cat is actively straining or vomiting, a vet needs to confirm the hairball is not blocking the intestines before you try home treatment.
Litter box problems that look like constipation
Sometimes a cat avoids the litter box because it is dirty, too small, located in a noisy or high-traffic area, or placed near the food and water bowls (cats naturally avoid toileting near where they eat). A stressed or anxious cat may also refuse to use the box. From outside the box, this looks like the cat is not pooping—but the cat may actually be going elsewhere in the house.
Check whether your cat is producing stool anywhere outside the box. If so, the issue is litter box aversion, not constipation. Provide a second box in a quiet location, scoop daily, and use unscented litter if your cat has been avoiding the box. If the cat is genuinely not producing stool and is also straining, the problem is digestive, not behavioral.
Medical conditions that cause chronic constipation
Older cats sometimes develop megacolon, a condition where the colon becomes enlarged and loses the muscle tone needed to move stool. Cats with hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid) can have constipation as a symptom. Kidney disease, diabetes, and neurological problems can also affect bowel function. These conditions require blood work and imaging to diagnose.
If your cat has constipation that comes and goes, or that does not improve with diet and hydration changes, a vet visit is necessary. Bring a record of when the constipation started, how often it happens, and what your cat eats. This information helps the vet narrow down the cause and recommend treatment—which might be medication, dietary change, or management of an underlying condition.
When to call the vet right away versus waiting
Call your vet when ready if your cat is vomiting, has not pooped in more than 24 hours, shows abdominal pain, is lethargic, or has lost appetite. These are signs of a blockage or serious illness. Also call right away if your cat is straining hard but producing no stool, or if you suspect your cat swallowed a foreign object (string, toy, bone).
Schedule a regular appointment (not an emergency visit) if your cat is mildly constipated but otherwise acting normal, eating well, and producing some stool. A vet can rule out medical causes and recommend dietary or lifestyle changes. If constipation is a new problem in an older cat, or if it keeps happening despite diet changes, an appointment is also the right move—chronic constipation in cats is often a sign of an underlying condition that benefits from early treatment.
Frequently Asked Questions
How long can a cat go without pooping?
Most cats poop once or twice a day. If your cat has not gone in more than 48 hours and is showing other signs of illness (vomiting, lethargy, loss of appetite), contact a vet. If the cat seems otherwise fine but has not pooped in 24 to 48 hours, a vet visit is still a good idea to rule out a blockage.
Can I give my cat a laxative at home?
Do not give your cat a human laxative or stool softener without vet guidance. Some are toxic to cats. A vet can recommend a cat-safe option like lactulose or a prescription stool softener if constipation is mild. If a blockage is present, laxatives can make it worse.
Is straining in the litter box always constipation?
No. Cats with urinary tract infections or blockages also strain in the box but produce urine, not stool. If your cat is straining frequently but you are not sure whether stool or urine is being produced, a vet visit is important—urinary blockages in male cats are emergencies.
Will wet food alone fix my cat's constipation?
Wet food increases water intake and often helps mild constipation, but it is not a cure-all. If constipation persists after switching to wet food for a few days, or if it happens repeatedly, the cause is likely something other than dehydration and needs veterinary evaluation.
Can stress cause a cat to stop pooping?
Stress can cause a cat to avoid the litter box, which may look like constipation. It can also slow digestion and contribute to constipation. If your cat's constipation started after a move, new pet, or other stressful event, reducing stress and ensuring a quiet, accessible litter box may help. If straining continues, a vet should rule out other causes.