One loose stool in a cat who is bright, eating, and drinking normally often settles on its own within a day. Diarrhoea that lasts more than a day or two, contains blood, or comes with vomiting, lethargy, or appetite loss needs a vet — and kittens should never be left to 'wait it out' for long.
Common reasons for a short bout
Everyday triggers include a sudden food change, a new treat that doesn't agree, eating something scavenged, hairballs irritating the gut, stress from visitors or a house move, and mild dietary indiscretion like rich table scraps. If you recently switched foods, transition more gradually — mostly old food, slowly increasing the new over a week. Keep a note of exactly what your cat ate in the 24 hours before it started; that detail is gold for your vet if it doesn't resolve.
The red flags that change the answer
Contact a vet promptly — the same day where possible — if you see:
- Diarrhoea beyond 24 to 48 hours, or watery stools many times a day
- Blood, black tarry stool, or a lot of mucus
- Vomiting alongside it, refusal to eat, or marked tiredness
- A kitten, a senior, or a cat with an existing condition who develops diarrhoea
- Signs of dehydration: dry gums, sunken eyes, or skin that stays tented when gently lifted
Kittens dehydrate remarkably fast because their bodies hold so little reserve, and what looks like a mild bug in an adult can become serious in a small kitten within hours. When in doubt, phone the clinic and describe what you're seeing; they will tell you how urgently to come in.
Sensible care at home for a mild case
For a bright adult cat with a single loose stool, keep fresh water in several spots, feed their usual food in small, regular meals unless your vet advises otherwise, and keep the litter box scrupulously clean so you can monitor frequency and appearance accurately. Don't give human anti-diarrhoea medicines, and don't withhold food for long periods — cats, especially overweight cats, should not go without eating for extended stretches. If things are not clearly improving by the next day, that is your answer: book the visit.
What your vet will want to know
Bring a fresh stool sample if you can, plus your notes: when it started, how many episodes, colour and consistency, any blood, recent food changes, new medications, indoor or outdoor access, and whether other pets are affected. That history, plus an exam, guides whether your vet suggests monitoring, testing, or treatment — decisions that belong in the clinic, not in a guess at home.
Keeping a sitter in the loop mid-episode
If a sitter is caring for your cat during an episode like this, KinsLe's Care Pass helps: it is a temporary, scoped link — the recipient needs no account or app — so you can share exactly what to watch for, feeding notes, and when to call the vet. Everyone caring for your cat works from the same instructions instead of a scribbled note on the counter. Through a Care Pass on KinsLe, your cat sitter for the next 48 hours can follow the exact stool count and appearance, the small regular meals and water spots, and the blood-or-vomiting triggers for calling the vet, without needing an account.