Diarrhoea in Cats: Causes, nutrition, and when to see a vet

Key Takeaways:

- Diarrhoea in cats can be caused by anything from diet changes and stress to infections or underlying health issues.

- Most mild cases will pass quickly, but ongoing symptoms or changes in behaviour mean it’s time to check in with your vet.

- Supporting your cat with a consistent, gut-friendly diet can help with recovery and reduce the chance of future stomach upsets.

The dreaded diarrhoea. Every cat owner knows the pain. Unpleasant for you, unpleasant for them, and unpleasant for your carpet. 

But it’s not just an inconvenience - diarrhoea can make your cat feel really unwell, and it’s understandably worrying when you don’t know what’s causing it.

In many cases, it’s mild and short-lived - like a one-off reaction to something they’ve eaten. But in other cases, diarrhoea can be a symptom of something more serious.

In this article, we’ll explore the most common causes of diarrhoea in cats, the symptoms to look out for, what to feed your cat during recovery, and when it’s time to speak to your vet.

Signs and symptoms

We probably don’t need to explain how you know if your cat’s got diarrhoea - if they have it, you’re very likely already dealing with the evidence… 

Loose, watery, or unformed stools. 

You might also notice:

• More frequent trips to the litter tray

• Straining or urgency when passing stools

• Accidents outside the litter box

• Changes in appetite or energy levels

• Bloating and/or gurgling sounds from their stomach

• Clumps of poo in their fur around their rear end and tail

• Stronger-smelling stools

• Loud flatulence

• Mucus in stools

Causes

There are lots of possible reasons your cat might get diarrhoea. Some causes are harmless, and others can be more serious.

Diet changes or food sensitivity

Cats don't just need time to get used to a new food - their digestive system does too. Switching diets too quickly can upset the balance of their gut and trigger diarrhoea. 

Some cats may also have sensitivities to certain ingredients, leading to loose stools or ongoing digestive issues. 

Introducing new foods should always be gradual - we recommend a gentle transition over 7-8 days, while keeping a careful eye on how your cat’s responding.

Toxic foods

Cats are pretty good at following their noses - and that can sometimes get them into trouble. Whether it’s spoiled food, table scraps, something they’ve found outdoors, or in more serious cases, exposure to something toxic. Eating outside of their usual diet can easily upset their stomach and lead to diarrhoea.

In many cases, this will resolve on its own over a couple of days. However, if you suspect your cat has eaten something toxic, this should always be taken seriously.

Alongside diarrhoea, you may also notice other symptoms such as:

• Vomiting

• Drooling

• Lethargy

• Pale gums

• Unsteadiness

In these cases, it’s a medical emergency, and you should contact your vet straight away.

Infections

Just like us, cats can get stomach bugs too. Bacterial or viral infections can upset their digestive system and cause diarrhoea.

Cats can pick up bugs from almost anywhere. But if your feline loves to venture outdoors, they're even more likely to come into contact with whatever's going around, especially if they hunt or scavenge.

Cats are masters at hiding when they're feeling under the weather, so diarrhoea might be the only sign they're fighting off an infection. 

But if it lasts for more than a couple of days, or it's accompanied by other worrying symptoms, it's always best to seek advice from your vet.

Parasites

Diarrhoea in cats can also be caused by worms and parasites, such as Giardia, and it's especially common in kittens and outdoor cats.

Kittens are particularly susceptible because their immune systems are still developing, while outdoor cats are more likely to come into contact with parasites through contaminated soil, standing water, prey animals, or the faeces of other animals during their adventures.

Keeping up with a regular parasite prevention plan can help reduce the risk. Your vet can recommend the most suitable worming schedule based on your cat's age and lifestyle.

As a general guide:

Kittens: Start worming from two to four weeks of age, then continue monthly until they're six months old.

Indoor cats: Worm six months to a year, depending on their lifestyle and your vet's advice.

Outdoor or high-risk cats: Worm every one to three months. If you've got a top explorer (where are our Bengals at?), they need to be kept up to date.

Stress and routine changes

Cats are creatures of habit, so even small changes to their routine can leave them feeling stressed. And just like us, stress can affect their digestive system and upset the balance of their gut microbiome.

Common triggers include:

• Moving house

• Welcoming a new pet

• Vet visits

• Changes to their daily routine

• Even a thunderstorm.

Stress-related diarrhoea often comes alongside other behavioural changes too, such as excessive grooming, becoming more clingy or withdrawn, hissing, aggression, or being more vocal than usual.

If your cat seems particularly anxious or they're experiencing repeated episodes of diarrhoea during stressful periods, it's worth speaking to your vet. 

They can help rule out any underlying health conditions and advise on ways to help your cat feel more settled.

Underlying health issues

If your cat's diarrhoea is persistent, keeps coming back, or doesn't have an obvious cause, it could be linked to an underlying health condition. 

Digestive disorders, such as inflammatory bowel disease (IBD), food allergies, or other long-term health issues, can all contribute to ongoing diarrhoea.

It's important to seek advice from your vet as soon as possible. The sooner the underlying cause is identified, the sooner your cat can get the right treatment and start feeling like themselves again.

When to see a vet

Not every upset stomach is an emergency. 

That said, sometimes diarrhoea can signal a serious health condition that requires urgent veterinary care.

We’d recommend you book an urgent appointment with a vet if:

• Your cat’s diarrhoea lasts for more than 24 to 48 hours

• There’s blood present

• Your cat’s vomiting as well

• Their appetite or energy drops noticeably

• Signs of dehydration appear (e.g. dry or sticky gums, reduced urination)

• It keeps recurring without a clear cause

• Your cat is a kitten or a senior

Treatment and aftercare

The best treatment for your cat’s diarrhoea depends on what’s causing it. 

Sometimes, a mild stomach upset will settle on its own, but ongoing or severe diarrhoea may need support from your vet.

They might recommend:

• Further tests. If your cat’s diarrhoea is persistent, severe, or keeps coming back, your vet may recommend additional testing to get to the root cause. This could include testing a sample of their stool to check for parasites, blood tests to assess their overall health and organ function, allergy tests, or an ultrasound to look at the digestive tract in more detail.

• Medication. If your cat has an infection, parasites, or another underlying issue, your vet will help you with the most appropriate treatment.

• Fluid support. Diarrhoea can cause extra fluid loss, so keeping your cat hydrated is especially important. This may include wet food and broths, alongside veterinary-recommended treatments.

• Dietary changes. Switching to a gentle, easily digestible complete cat food or a veterinary digestive diet can help settle your cat’s stomach. Just remember to transition their new food gradually to avoid further stomach upsets.

• Probiotics. This can include supplements, specially formulated cat foods. You can also look out for ingredients like Chicory Root or Psyllium Husk, which are prebiotic fibres that help feed beneficial gut bacteria.

What should I feed my cat after diarrhoea?

Once your cat’s stools start returning to normal, gradually getting them back onto their usual diet can help prevent another upset.

Foods that support digestive health can include:

• Highly digestible proteins. Think lean proteins like Chicken, Turkey, or White Fish, or specially formulated digestive or gastrointestinal diets designed for sensitive stomachs.

• Fibre sources. Ingredients like Psyllium Husk, Beet Pulp, or Pumpkin are often used to help support firmer stools and healthy bowel movements.

• Prebiotics and probiotics. These support a healthy balance of gut bacteria.

• Moisture-rich foods. Wet foods and broths can help support hydration, which is especially helpful after fluid loss.

How to reduce the risk of diarrhoea in cats

While you can’t prevent every upset stomach, there are a few simple ways to support your cat’s digestive health:

• Introduce new foods slowly. Sudden diet changes are a common cause of diarrhoea, so transition gradually over a couple of weeks.

• Keep their diet consistent. Avoid frequent changes unless recommended by your vet.

• Stay on top of worming.

• Be careful with human foods. Keep scraps, spoiled food, and poisonous plants out of reach.

• Support a calm routine. Reducing stress and keeping their environment predictable can help support a healthy gut. This can include regular mealtimes, a quiet space to retreat to, and familiar people around them.