Diarrhoea in Cats: Causes, Home Care, and When to See a Vet

Diarrhoea in cats is the passing of loose or watery stools, and while most short bouts come from a diet upset or parasites and settle within a day or two, it always matters because cats can dehydrate quickly. The job for an owner is to judge the cause, support your cat safely at home, and know the point at which loose stools stop being a nuisance and become a reason to call the vet.

What diarrhoea in cats is

Diarrhoea means stools that are softer, more frequent, or more urgent than your cat’s normal, often with more water and sometimes mucus or blood. It is a symptom, not a disease, and it reflects the gut moving contents through too fast or absorbing too little fluid. Vets broadly split it into acute (sudden, lasting up to a few days) and chronic (lasting beyond about three weeks or recurring), and that distinction shapes how worried to be. A single soft stool in a bright, playful cat is rarely a crisis; persistent or bloody diarrhoea is a different matter. Knowing your cat’s usual litter-box habits is what lets you notice the change at all, which is the same baseline thinking covered in our guide to the signs your cat is sick.

Common causes of diarrhoea in cats

Most cases trace back to one of three groups: diet, parasites, or underlying illness. Diet is the everyday culprit: a sudden change of food, a rich treat, scavenged scraps, or a food intolerance can all loosen the stools, which is exactly why diet changes should be made gradually over about 7 days rather than overnight. Parasites are the next big group, and the Cornell Feline Health Center lists intestinal worms (roundworms, hookworms) and protozoa such as Giardia among the common causes, especially in kittens and cats with outdoor access. The third group is illness: infections, inflammatory bowel disease, pancreatitis, and in older cats conditions like hyperthyroidism or kidney disease can all show up as loose stools. Eating something toxic counts too; the ASPCA lists onion, garlic, chocolate, grapes and raisins, and xylitol among foods to keep away from pets, and several cause digestive upset before anything worse. Matching the diet to your cat’s life stage, covered in our cat nutrition guide, removes one of the most common triggers entirely.

The dehydration risk

The single biggest danger with diarrhoea is dehydration, because every loose stool carries water and electrolytes out of the body. A cat is normally about 60 percent water, and that loss adds up fast when stools are frequent or watery, faster still if vomiting is happening at the same time. Kittens and senior cats have the least reserve and tip into trouble soonest. You can check for early dehydration with two quick tests: gently lift the skin over the shoulders (it should spring straight back, not stay tented) and feel the gums (they should be moist and slippery, not tacky or dry). A cat that is also lethargic, refusing water, or sunken-eyed needs a vet without delay. Because diarrhoea and vomiting so often travel together, it is worth reading our companion piece on vomiting in cats so you can recognise when both at once tips the balance toward urgent care.

Safe home care

For a bright, well-hydrated adult cat with mild diarrhoea, sensible home care is reasonable for the first 24 to 48 hours. Keep fresh water available at all times and encourage drinking; our notes on getting a cat to drink more water help here. If your vet agrees, offer small amounts of a bland, easily digestible diet for a day or two, then transition back to the normal food gradually over about 7 days. The one firm rule is what not to do: never give human anti-diarrhoea medicines. International Cat Care and other authorities are clear that products meant for people, including those containing loperamide or salicylates, can be toxic to cats, and dosing a cat at home can mask a problem that needs proper treatment. When in doubt, phone the practice and describe what you are seeing before giving anything at all.

When I switched my older cat to a new senior food in one go rather than over a week, I learned this the hard way: within a day she had soft, urgent stools and a couple of litter-box misses, even though she was eating happily and behaving normally otherwise. I backed off, mixed the foods slowly over the following week, and it settled completely. It was a small, harmless episode, but it made the seven-day rule stick for good, and it taught me to watch the litter tray as closely as the food bowl.

When to see a vet

See a vet if diarrhoea is severe, persistent, or comes with other warning signs, rather than waiting it out. As a working rule, book a check if loose stools last more than 24 to 48 hours, recur often, or contain fresh blood. Go promptly, the same day, if your cat also has repeated vomiting, is lethargic or off food, has a painful or bloated belly, or shows signs of dehydration. Lower the threshold for kittens, for senior cats (the AAFP and AAHA recommend vet checks every 6 months from around 11 years), and for any cat with a known chronic illness, because all of these dehydrate faster and tolerate it less well. The same instinct that something is simply off, described in our overview of when to take a cat to the vet, is worth acting on. Your vet can examine your cat, test a stool sample for parasites, and look for the causes you cannot see at home.

This guide is general information, not a diagnosis. Anything that worries you about your own cat should be checked by your vet, who can examine your cat and knows its history.