Cat with diarrhoea — when to worry
Mild loose stool in a bright, eating cat can be monitored briefly; any blood, lethargy, refusal to eat for over 24 hours, or kitten with diarrhoea needs vet contact today.
Recognise the signs
- Loose, soft, or watery stool in or near the litter tray
- Mucus or blood in stool
- Frequent visits to the litter tray
- Soiling outside the tray (often a sign of urgency or pain)
- Vomiting alongside diarrhoea
- Weight loss, dull coat, refusing food
- Dehydration — tacky gums, sunken eyes, slow skin tent at the scruff
First aid steps
- Do not starve a cat for more than a few hours — fatty liver disease (hepatic lipidosis) is a real risk after 2–3 days off food.
- Offer small amounts of bland food — boiled chicken, white fish, or a vet-recommended sensitive diet.
- Provide fresh water; consider a water fountain to encourage drinking.
- Photograph the stool for the vet.
- Note frequency, volume, and any tray-soiling pattern.
- If the cat refuses food for over 24 hours, phone the vet.
Do NOT
- Do not give human anti-diarrhoeals — many contain bismuth (salicylate, dangerous in cats) or are unsafe.
- Do not give cow's milk — most cats are lactose-intolerant.
- Do not starve a cat for more than a few hours.
- Do not assume diarrhoea in a thin older cat is mild — investigate for hyperthyroidism, kidney disease, or IBD.
- Do not delay for a kitten or any cat with vomiting alongside.
When to phone the vet immediately
- Any cat off food for 24 hours
- Blood in stool or black tarry stool
- Vomiting alongside diarrhoea
- Lethargy, hiding, or jaundice
- Kitten under 6 months — fluid loss is fast and panleukopenia is serious
- Outdoor cat with possible toxin or hunting exposure
- Diarrhoea persisting more than 48 hours
Signs that can usually wait for a routine appointment
- A single soft stool in a bright, eating, drinking cat with no other signs can usually be monitored at home for 24 hours.
Common causes
- Dietary indiscretion or sudden food change
- Worms or other parasites (especially in outdoor cats and kittens)
- Bacterial infection — Campylobacter, Salmonella
- Viral infection — feline panleukopenia (kittens), feline coronavirus
- Inflammatory bowel disease (IBD)
- Hyperthyroidism (older cats)
- Chronic kidney disease
- Pancreatitis
- Food intolerance or allergy
- Toxin exposure
What the vet will need to know
- Frequency, volume, and appearance of stool
- Indoor/outdoor lifestyle
- Recent diet changes
- Worming and flea treatment history (and product name)
- Other cats in the household and whether affected
- Weight changes over recent months
- Photo of the stool
Aftercare
- Continue prescribed diet or medication as directed.
- Probiotic paste from the vet often helps.
- Stool sample testing if parasite or infection suspected.
- Address underlying conditions (kidney support, thyroid medication).
- Keep a brief log for the vet — frequency, appearance, appetite.
Prevention
- Stay current on worming, especially for outdoor cats and kittens.
- Transition foods over 5–7 days.
- Avoid feeding cow's milk and rich human leftovers.
- Multiple clean litter trays in multi-cat homes.
- Annual senior bloods from age 8 catch chronic disease early.
Breed-specific notes
- Siamese and Oriental breeds over-represented in IBD and food sensitivity.
- Persians appear prone to chronic gut sensitivity in some lines.
Frequently asked questions
Why is not eating more dangerous in cats than dogs with diarrhoea?
Cats can develop hepatic lipidosis (fatty liver disease) after 2–3 days off food, particularly if they are overweight. The liver becomes overwhelmed processing fat stores and can fail. This is why cats with diarrhoea should not be starved — they need small amounts of bland food, not a fast.
My kitten has diarrhoea — is it urgent?
Yes. Kittens dehydrate within hours, not days, and viral causes (panleukopenia) and parasites can be life-threatening. Any kitten with diarrhoea, particularly with vomiting, lethargy, or refusal to eat, should see a vet the same day.
How can I tell if my cat is dehydrated?
Lift the loose skin at the scruff and let go — it should snap back instantly. Slow return (over 1–2 seconds) suggests dehydration. Tacky or dry gums and sunken eyes are other signs. Dehydrated cats need vet fluids; you cannot reliably rehydrate at home.