Cat Diarrhoea: Vet Advice on Causes, Care and When to Worry

The appearance of your cat’s diarrhoea can reveal clues on what's going on: soft or unformed stools often follow diet changes or stress, while watery, mucus-coated, or hair-filled poo may suggest parasites, inflammation, or poor gut motility.

Unusual colours like yellow, green, red, or black can point to bile issues, bleeding, or malabsorption, and should always be discussed with your vet.

For a more detailed guide on different types of poo and key indicators, check out our expert cat poo chart with visual cues.

Diarrhoea in cats is usually a sign that the digestive system is irritated or out of balance, common causes include sudden diet changes, parasites, infections, stress, or underlying medical conditions.

Cat diarrhoea isn’t a condition in itself, it’s a symptom. It signals something’s off in your cat’s digestive tract.

Diet Changes and Food Intolerances

Sudden changes in diet are one of the most common causes. Even switching to a new diet too quickly can trigger loose stools, which is why a slow and steady transition is recommended when making the switch.

Some cats also have intolerances to ingredients like beef, dairy, or grain. These sensitivities disrupt digestion, resulting in runny cat poo that may look oily, smells terrible or be unusually soft.

Parasites, Infections, and Toxins

Worms, Giardia, and other parasites often cause diarrhoea, especially in kittens. Bacterial infections or exposure to toxins (like houseplants or spoiled food) can also inflame the gut and cause quick and watery poos.

Stress and Gut Imbalance

Cats under stress from vet visits, house renovations, boarding, or new pets can develop stress-related diarrhoea. The gut microbiome can also shift after antibiotics or illness, disturbing normal stool formation.

Underlying Conditions

• Recurring or chronic diarrhoea may point to more serious problems like:
• Inflammatory Bowel Disease (IBD)
• Hyperthyroidism
• Liver or kidney issues
• Pancreatic insufficiency

If your cat has persistent diarrhoea but seems fine otherwise, don’t ignore it. Early changes might be a clue that something more complex is under the surface.

“It’s not unusual for cats to have a short bout of diarrhoea after a diet change or stressful event. The key is to notice early changes and support the gut before things escalate: many cases are mild and easy to manage with the right approach from the get-go.”

- Dr Lisa Deering

For many cases, good nutrition is the first line of support. The right cat food can often be a good first step to supporting the gut and speed up recovery if symptoms are mild and your cat is still eating and behaving normally.

Bland, Easy-to-Digest Meals (short-term solution)

For short-term diarrhoea, offer small portions of bland foods for no more than 2 days:

• Plain cooked chicken (skinless, boneless)
• Steamed white fish
• Cooked pumpkin (plain, no seasoning)

Avoid dairy, oils, or table scraps. Keep meals cool or slightly warm to encourage appetite.

Sensitive Stomach or Limited Ingredient Diets (medium to long-term solution)

Transition gradually to a high-quality, sensitive-stomach cat food. Look for:

• Food labelled as limited ingredient or containing a single animal protein (like turkey or chicken)
• Added prebiotics or fibre

For more detailed recommendations, check out this expert guide to the best vet-recommended cat food for sensitive stomachs.

Hairball Support and Fibre Enrichment

If diarrhoea is paired with hair in the stool, especially in long-haired breeds, your cat may need more fibre. Unflavoured psyllium husk (⅛ to ¼ teaspoon daily) or plain pumpkin (1 to 2 teaspoons with meals) can help regulate digestion in adult cats without irritating the gut. Just make sure your cat has access to plenty of fresh water.

Short-term, mild diarrhoea (lasting 1-2 days) can often be managed at home, provided your cat stays hydrated and alert. Along with a bland diet, what to try:

• Hydration support: Offer fresh water in multiple spots. Chicken bone broth (low sodium, no onion or garlic) can help increase intake, along with supplements that assist with hydration, like hydra care.
• Probiotics: Use vet-formulated cat probiotics to rebalance gut flora after antibiotics, stress, or food trials.
• Litter box monitoring: Keep tabs on frequency, texture, and any changes in colour or smell. Take photos if needed (your vet will thank you).

While not every case is avoidable, many episodes of diarrhoea can be prevented by building simple habits into your cat’s routine.

Feed a consistent, digestible diet

Stick to high-quality, vet-recommended cat food. Avoid frequent changes in meat proteins or formula, which can disrupt digestion.

Transition new foods slowly

Introduce any new diet over 7–10 days. Sudden switches are one of the most common causes of short-term diarrhoea.

Use gut support during stressful events

If your cat is boarding, recovering from illness, or adjusting to change, consider a cat probiotic supplement to support their gut microbiome.

Keep parasite protection up to date

Worms are a frequent culprit. Ensure you’re following a vet-advised deworming schedule, especially for outdoor cats or multi-pet households.

Regular grooming matters

Especially for long-haired cats, regular dematting and brushing helps reduce the amount of hair swallowed, which can contribute to both constipation and diarrhoea.

Clean litter trays regularly

A clean litter tray helps you spot early changes and encourages healthy toileting habits.

Some cases of diarrhoea need a vet’s attention, especially when symptoms linger, worsen, or come with changes in behaviour.

Don’t wait too long to seek veterinary care. Book an appointment if:

• Diarrhoea lasts longer than 24–48 hours
• You notice blood or mucus in the stool
• Your cat becomes lethargic, refuses food, or vomits
• Your cat is a kitten, senior, or chronically ill

When a cat presents with diarrhoea, the goal isn’t just to stop the symptom, it’s to find the cause. Diagnosing the underlying issue helps guide the right treatment and avoid unnecessary guesswork.

History and Symptom Review

Your vet will begin by asking detailed questions about:

• When the diarrhoea started and how it has changed
• Any recent diet changes or new foods
• Litter box habits and stool appearance
• Behavioural shifts like hiding or vomiting

Photos of the litter tray or a stool sample can be especially helpful if possible.

Physical Examination

Your vet will check hydration, feel the abdomen, assess overall body condition, and look for signs of inflammation, bloating, or dehydration.

Diagnostic Testing

Depending on the case, your vet might recommend:

• Faecal tests for parasites or bacterial overgrowth
• Blood work to check for systemic illness
• Imaging (like X-rays or ultrasound) to rule out blockages or inflammation
• Diet trials to pinpoint food sensitivities
• Endoscopy or biopsy for chronic or complex cases

For many cats, diarrhoea resolves with dietary changes or basic support. But when it doesn’t, these tools help uncover what’s going on, and get your cat feeling better faster.

Why does my cat have diarrhoea all of a sudden?

The most likely culprits are a new food, stress, or exposure to something unusual. Sudden cases usually have a short-term cause, but still need monitoring.

What’s a good home remedy for cat vomiting and diarrhoea?

Try feeding small, bland meals like boiled chicken with no seasoning and adding a probiotic. Keep water available and avoid treats or new foods.

What is the best cat food for diarrhoea recovery?

Look for vet-recommended sensitive-stomach formulas or hydrolysed diets. These are easier to digest and help restore gut balance.

Can stress cause diarrhoea in cats?

Yes. Cats are sensitive creatures. Even minor disruptions in routine can lead to digestive upset.

What if my cat has diarrhoea but seems fine otherwise?

It’s worth noting and keeping track. If it continues for more than a day or two, or if it recurs, it’s time to get your vet involved.

Diarrhoea is common in cats and often mild, but it can also signal something more serious. By keeping an eye on your cat’s litter box habits and acting early with diet tweaks or vet care, you can help prevent bigger problems. If diarrhoea lasts more than a day or two, or you see worrying signs like blood, vomiting, or lethargy, book a vet visit right away. With the right support, most cats recover quickly and comfortably.

This article was written by Dr Lisa Deering