When a cat has loose or watery stools, it’s a clear sign something is off. Cats often hide illness, so diarrhoea can be one of the first visible clues. Sometimes it’s a short term stomach upset from new food, stress, or a hairball, and sometimes it indicates parasites, infection, medication effects, or a deeper health problem.
Diarrhoea is a symptom, not a diagnosis. It means the gut isn’t absorbing water or nutrients properly, or the intestines are irritated and moving contents too quickly. Cats have unique traits that affect how diarrhoea appears and what it means: they are obligate carnivores with sensitive metabolisms and small stomachs, they groom frequently, and they can decline quickly if they stop eating.
Common causes include recent diet changes, stress, parasites, bacteria or viruses, toxins, medication reactions, or organ disease. Watch your cat’s appetite, energy, grooming, and litter box habits, as these behaviours often reveal how serious the problem may be.
- Food and treats. Cats are sensitive to sudden diet changes and to human food. Even one meal can trigger loose or greasy stools.
- Food intolerance or allergy. Repeated diarrhoea after the same food suggests intolerance; signs may be subtle and chronic.
- Stress and routine disruption. Cats thrive on routine. Moving house, visitors, boarding, or new pets can trigger digestive upset.
- Parasites. Protozoa such as Tritrichomonas foetus, Giardia, and Cryptosporidium, intestinal worms, and coccidia are common causes, especially in kittens, pedigree cats, or multi cat households.
- Infections and inflammation. Bacterial enteritis, viral infections, and inflammatory bowel disease can cause sudden or ongoing diarrhoea.
- Medications or toxins. Some antibiotics, NSAIDs, or spoiled food, rancid fat, or toxic plants can irritate the gut.
Changes in appetite, behaviour, or energy alongside diarrhoea are significant signs.
Some infections need specific tests or treatments, and some persist in the environment. Key feline pathogens include:
- Tritrichomonas foetus: causes chronic, often mucoid diarrhoea in kittens, pedigrees, and multi cat homes.
- Giardia intestinalis: can cause intermittent or chronic diarrhoea; diagnosis may require repeated testing.
- Cryptosporidium spp.: uncommon but notable in young or immunocompromised cats.
- Feline panleukopenia virus: a severe disease with fever, vomiting, and diarrhoea; vaccination prevents it.
- Feline coronavirus (FCoV): usually mild, but in rare cases can lead to FIP.
- Bacterial causes such as Clostridium perfringens, Salmonella, and Campylobacter. Some can affect humans too.
Most of these can be identified through faecal testing such as microscopy, flotation, antigen, or PCR. Early testing and good hygiene help manage them effectively.
If your cat seems unwell but not in immediate danger, these steps help you gather information before visiting the vet:
- Observe and record. Note stool frequency and appearance such as watery, mucus, bloody, or greasy, along with appetite, vomiting, and behaviour.
- Encourage eating. Cats need steady protein intake. Offer small, appealing portions of favourite wet food. If they refuse, contact your vet.
- Support hydration. Offer fresh water often; small sips are easiest. Signs of dehydration include sunken eyes, dry gums, or reduced skin elasticity. Seek help if your cat will not drink.
- Avoid human food. Fatty foods can worsen diarrhoea. Use only vet recommended bland diets if advised.
- Litter box care. In multi cat homes, provide a clean tray for the sick cat to track symptoms. Clean trays, bedding, and bowls regularly and wear gloves when handling waste.
- Collect a stool sample. Scoop a fresh deposit into a clean, sealed container for testing.
Seek veterinary attention straight away if your cat has:
- Repeated vomiting with diarrhoea
- Blood in stool or large amounts of mucus
- Lethargy, collapse, or pale gums
- Severe abdominal pain or a firm, swollen belly
- Refusal to eat or drink
- Signs of dehydration
- Fever, weakness, or shock
Kittens, elderly cats, and those with chronic illness are at higher risk and can worsen quickly.
Typical diagnostic steps include:
- Faecal testing for parasites such as Giardia and Tritrichomonas. Sometimes repeat testing is needed due to intermittent shedding.
- Retesting after treatment to confirm resolution.
A good plan balances your cat’s symptoms, likely causes, and the household setting.
- Change diets gradually over 7 to 10 days.
- Keep litter boxes and bedding clean.
- Maintain regular parasite control, especially for kittens and outdoor cats.
- Stay current with vaccinations and health checks.
- Isolate and clean if needed to prevent spread in multi cat homes.