Diarrhea in Cats: When to Worry and What to Do.

Diarrhea means loose, watery or unusually frequent stools. In cats it can be a short-lived upset after a food change or a stressful day, or a sign of something that needs treatment, from parasites to thyroid or bowel disease. Because cats can become dehydrated, and kittens very quickly, it’s worth knowing when you can watch at home and when your cat needs to be seen.

What healthy cat poop looks like

Normal cat stool is brown, formed and firm enough to pick up without smearing. Most adult cats pass stool about once or twice a day, though this varies. Diarrhea is a change from your own cat’s normal: softer, runnier, more frequent, smellier than usual, or with mucus or blood. You may also notice accidents outside the litter box, straining, or a dirty back end.

Common causes

Short-term causes

• A sudden diet change. Switching foods too fast is one of the most common triggers. See how to change cat food gradually.
• Eating something unusual, such as spoiled food, table scraps, dairy or something from the trash.
• Stress, such as travel, a vet or boarding stay, moving house or a new pet.
• Kittens moving to solid food.

Medical causes

• Intestinal parasites such as roundworms, hookworms, Giardia and coccidia. See worms in cats.
• Infections, including viral infections such as feline panleukopenia, which is serious in unvaccinated cats and kittens. Keep vaccines up to date with our cat vaccination schedule.
• Food allergies or intolerances.
• Inflammatory bowel disease and other ongoing gut conditions.
• Hyperthyroidism, kidney disease or liver disease, especially in older cats.
• Some cancers, such as intestinal lymphoma.
• Toxins and some medicines.

Diarrhea that lasts more than about two weeks, or keeps returning, is usually called chronic and nearly always needs tests to find the cause.

When to see a vet

Cornell’s Feline Health Center advises a vet visit for diarrhea lasting longer than a day or two, and as soon as possible when there are other signs such as poor appetite, lethargy or vomiting. Kittens are more fragile: they dehydrate easily and can develop low blood sugar, so any gut upset in a kitten deserves prompt attention.

Urgent: go to a vet straight away if your cat has large amounts of blood in the stool, very watery diarrhea with vomiting, is weak or collapsed, has pale gums, seems to be in pain, or may have eaten something poisonous.

Signs of dehydration

• Sticky or dry gums
• Sunken eyes
• Skin at the scruff that doesn’t spring back quickly when gently lifted
• Weakness or lethargy

Make sure fresh water is always available. Some cats drink more readily from a fountain or a wide bowl; see cat water bowls and fountains. If your cat is drinking less than usual, our guide on why your cat isn’t drinking much water may help.

Caring for your cat at home

For a mild case in an adult cat that is otherwise bright and eating:

1. Keep fresh water available and check that your cat is drinking.
2. Stick to its usual food, unless your vet suggests otherwise. Avoid treats, table scraps and milk. Don’t stop food for long periods: cats shouldn’t go without eating.
3. Ask your vet about a bland or sensitive-stomach diet. Vets often prescribe a low-fat, easy-to-digest food for a few days.
4. Keep the litter box very clean and note how often your cat goes and what the stool looks like. A photo can help your vet.
5. Keep your cat clean. Gently wipe the back end with a damp cloth if it gets soiled. Long-haired cats may need a little trimming around the rear.
6. Don’t give human medicines. Some over-the-counter anti-diarrhea products are harmful to cats. Only use what your vet prescribes, including dewormers.

What happens at the vet

Your vet will ask about diet, recent changes, how often your cat is going, what the stool looks like, any vomiting, and parasite treatments. Bring a fresh stool sample if you can. Common tests include a fecal test for parasites, blood tests, and sometimes X-rays, ultrasound or diet trials. Treatment depends on the cause and may include parasite treatment, a special diet, fluids for dehydration, probiotics or other medicines.

Preventing diarrhea

• Change foods slowly, over about a week
• Keep up with deworming and vaccinations as your vet recommends
• Keep trash, toxic plants and human food out of reach; see plants and foods poisonous to cats
• Reduce stress around changes such as moving or new pets
• Book regular checkups, especially for older cats

Diarrhea often goes together with other signs. If your cat is also vomiting, see why is my cat vomiting. If it seems uncomfortable, our guide to signs your cat is in pain can help, and signs your cat is sick covers other changes to watch for.

Frequently asked questions

How long can diarrhea last in a cat before I see a vet?

If your adult cat is otherwise well, mild diarrhea that doesn’t improve within 24–48 hours should be checked by a vet. Kittens, or cats with vomiting, poor appetite, lethargy or blood in the stool, should be seen sooner.

Can a change of food give my cat diarrhea?

Yes. A sudden food switch is a common cause. It usually settles within a few days. To avoid it, mix the new food in gradually over about a week.

Is diarrhea in kittens dangerous?

It can be. Kittens dehydrate quickly and can develop low blood sugar, and diarrhea can be a sign of parasites or serious infections. Contact your vet promptly if a kitten has diarrhea.

Can I give my cat human anti-diarrhea medicine?

No. Some over-the-counter medicines for people are harmful to cats. Always ask your vet, who can prescribe safe treatment once the cause is known.

Sources and further reading

• Cornell Feline Health Center: Diarrhea
• Small Door Veterinary: Diarrhea in cats