My cat has diarrhoea: causes, home care & when to call the vet

Loose stool in a cat is uncomfortable for everyone and often more serious than the equivalent in a dog. Cats are quiet sufferers and dehydrate quickly, so a 48-hour rule that works for dogs is too generous for cats — particularly for kittens and seniors.

Acute diarrhoea (less than 7 days) is most often from diet change, stress, or a passing infection, and usually resolves with gentle home care. Chronic diarrhoea (more than 3 weeks, intermittent or continuous) is a different problem and almost always needs investigation — inflammatory bowel disease, food allergy, parasites, hyperthyroidism, and small-cell lymphoma all sit in this picture.

Note colour, consistency, frequency, blood, mucus, and whether the cat is making it to the litter tray. That information narrows the differential dramatically.

Common causes

What you can safely do at home

• Do not fast cats — even short fasts risk hepatic lipidosis. Offer small frequent meals.
• Try a temporary bland diet of plain boiled chicken (no skin, no seasoning). Cats are reluctant to switch — warming helps.
• Probiotic paste designed for cats (FortiFlora) can shorten recovery.
• Ensure fresh water is plentiful and accessible — wet food is even more important than usual.
• Restrict the cat to one room with a clean litter tray so you can monitor every episode.
• If diarrhoea persists beyond 24 hours, or any red-flag sign appears, see a vet rather than continuing to wait.

These steps are general guidance for an otherwise well, healthy adult pet. If your cat is a puppy/kitten, a senior, or has a known chronic condition, call a vet rather than waiting it out.

What to expect at the vet

The vet will usually:

• Faecal sample for parasites, giardia, and panleukopenia if a kitten
• Bloodwork including thyroid (T4) and feline pancreatic lipase
• Urinalysis to assess hydration and kidney status
• Abdominal ultrasound if chronic or paired with weight loss
• Anti-diarrhoeal medication and fluids; sometimes a hydrolysed-diet trial

Useful questions to ask:

• Is this acute or chronic? Should we investigate now or wait?
• Should we ultrasound today?
• Is an elimination diet trial appropriate, and which food do you recommend?
• What's the next step if diet trial fails?

How to reduce the chance of it happening again

• Year-round worming on a vet-recommended schedule.
• Keep food and protein changes slow (7–10 days).
• Annual wellness exam; senior cats from age 7 with bloodwork including thyroid.
• Stable, low-stress environment; multi-cat households need one tray per cat plus one extra, in separate locations.
• No lilies in the home, and no human medications within reach.

Frequently asked questions