Cat diarrhoea: causes and when to worry
A day or so of loose stools in a cat who is otherwise bright, eating and drinking is usually manageable at home. The thing that changes the picture is a cat who stops eating — cats tolerate that far worse than dogs do.
Get this seen
This is worth a call to your vet rather than waiting to see how it goes, particularly if it has lasted more than a day or your pet is otherwise off-colour.
The threshold that matters
Ring your vet the same day if your cat has stopped eating, is vomiting as well, is hiding or unusually quiet, if there is blood, or if the diarrhoea has continued beyond about 48 hours.
A cat that does not eat for a couple of days can develop a serious liver problem as a direct result. That is why "off their food" is treated more seriously in cats than in dogs, and why it is the single most useful thing to report.
Kittens dehydrate quickly and should be seen sooner. So should older cats, and any cat with a known condition.
What causes it
Diet is the most common trigger — a change of food introduced too fast, a new treat, or cow’s milk, which many cats cannot digest despite the stereotype.
Parasites and infections are common, particularly in kittens, outdoor cats and multi-cat households. Worming status is one of the first things a vet will ask about.
Stress genuinely does it. A new cat, building work, a house move or a change in routine can all show up as loose stools in a sensitive cat.
Longer-term causes include food intolerance, inflammatory bowel disease, an overactive thyroid and kidney disease. Diarrhoea that keeps returning is a different question from a one-off and deserves investigating.
What helps
Keep water available and easy to reach. Some cats drink noticeably more from a wide, shallow bowl away from the food, or from running water.
Feed small, frequent, plain meals rather than withholding food. Withholding is no longer standard advice and is particularly risky in cats for the liver reason above.
Make any food change gradually over a week. If you have just switched food and the diarrhoea started, going back to the old food and transitioning more slowly often resolves it.
Keep the tray scrupulously clean and, in a multi-cat home, note which cat it actually is — owners are often surprised. That answer matters if a vet visit follows.
What can help
Things we stock that owners commonly use alongside a vet’s advice — not a substitute for it.
ANIGENE Pet Urine Eliminator 750ml – Citrus Fragrance
Breaks down urine crystals at the source rather than masking the smell — helps fully eliminate odours and reduce repeat marking behaviour.
£12.99
Plastic Cat Litter Tray — Large & XL
A sturdy plastic litter tray in two generous sizes — practical, no-fuss, and easy to clean.
From£11.49
Plastic Cat Litter Scoop
A no-nonsense plastic litter scoop for daily tray maintenance — comes in assorted colours.
£4.99
PowAir Odour Neutralising Gel Jar 400g — Pet Safe, Natural Formula
An open-jar odour neutraliser made from essential oils that quietly gets rid of pet smells for up to 60 days — no sprays, no fuss.
£12.99
Common questions
- When should I take my cat to the vet for diarrhoea?
- The same day if they have stopped eating, are vomiting too, are hiding, if there is blood, or if it has lasted beyond about 48 hours. Kittens and older cats should be seen sooner.
- Should I starve my cat with diarrhoea?
- No. Withholding food is out of date advice and is riskier in cats, because a cat that does not eat for a couple of days can develop serious liver problems. Offer small, frequent, plain meals.
- Can I give my cat milk?
- Cow’s milk is a common cause of diarrhoea in cats, most of whom do not digest lactose well as adults. It is best avoided, particularly while their stomach is already upset.
- Can stress cause diarrhoea in cats?
- Yes. New pets, building work, moves and routine changes are all recognised triggers. It usually settles as the situation does, but the same warning signs still apply.
- How do I tell which cat it is in a multi-cat house?
- Separating cats temporarily, or using a food dye recommended by your vet, are the usual approaches. It matters, because treating the wrong cat wastes time.
Related
Sources
Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.
Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.