Why Does My Cat Have Diarrhoea?

Cat diarrhoea often settles, but it can be serious, so it helps to know when to call your vet.

Quick Answer

Diarrhoea means soft to liquid faeces, and it is a sign of a problem rather than a disease in itself; most cases improve quickly, but some are serious and need a vet.
Contact your vet if the diarrhoea lasts longer than 24 hours, gets worse, or comes with other symptoms such as vomiting, lethargy, loss of appetite, mucus in the poo, or a painful tummy.
Speak to your vet as soon as it starts if the cat is a kitten, is elderly, or has an underlying health condition. Kittens and elderly cats are more at risk of dehydration.
Treat a suspected blockage, a swallowed object such as string or tinsel, or suspected poisoning as an emergency and contact a vet immediately.
If there is blood in the diarrhoea, or the poo is black or very dark, ask your vet for an emergency appointment.
Do not starve your cat or give it milk; offer plenty of fresh water and small, bland meals instead.

Cat diarrhoea is when faeces become soft to liquid. Normal, healthy cat poo is firm and dark brown. Many things can cause diarrhoea, and most cases improve quickly. However, some are more serious and need treatment from a vet.

This guide covers the common causes, what you can do at home for a mild case and when to get help.

Overhead view of a tabby cat eating dry food from a green bowl on paving slabs – a sudden food change is one possible cause of cat diarrhoea

Emergency: Contact a Vet Immediately If…

You know your cat has swallowed something it should not have, such as string, thread, tinsel or small bones, or you suspect a blockage.
Your cat has severe tummy pain or collapses, along with vomiting and diarrhoea. In a kitten this can mean part of the intestine has become stuck.
You think your cat has eaten something poisonous, or a kitten may have swallowed a toxin or any medication.
There is blood in the diarrhoea, or the poo is black or very dark. Ask for an emergency appointment.

Call your vet, or the nearest emergency vet if your vet is closed, straight away. Do not wait to see if it settles.

Common causes of cat diarrhoea

Only a vet can say what is behind your cat's diarrhoea. These are causes that UK vets and cat charities list.

A sudden change in diet

Many cats are sensitive to a sudden change of food, or to food not designed for cats, such as human foods or too many treats. Scavenging food outside can have the same effect, and so can eating non-food items.

If you need to change your cat's diet, do it gradually.

Milk and food intolerance

Most cats are lactose intolerant, and dairy can lead to diarrhoea. For that reason, do not give milk to your cat. Food or ingredient intolerances and allergies can also contribute to digestive signs.

Worms and other parasites

Worms are a common cause, and so are gut parasites such as giardia, cryptosporidium and tritrichomonas. Worms are particularly common in kittens, because they can be passed on in the womb and through the mother's milk.

See How Do I Know If My Cat Has Worms? for more.

Infections

Infectious diseases caused by viruses, bacteria and parasites are common causes of digestive problems, especially in young cats. Less common causes include gut infections such as Salmonella and Campylobacter, and viruses such as feline panleucopenia virus, FeLV and FIP virus.

Pale cream-grey cat lying on its side on a wooden floor, looking at the camera – watch how bright your cat is when you notice cat diarrhoea

Stress

Stress can also cause diarrhoea. Vomiting and diarrhoea are very common in kittens, particularly recently rehomed ones, and many of these cases are straightforward.

Gut and organ problems

Pancreatitis, inflammatory bowel disease, liver disease and kidney disease can all cause diarrhoea. So can some hormonal conditions, such as an overactive thyroid, and digestive cancers. PDSA lists inflammatory bowel disease, liver disease, kidney disease and cancer among the less common causes.

Liver or kidney disease can cause toxins to build up, which leads to loss of appetite, vomiting and diarrhoea. Our guides to the signs of an overactive thyroid in cats and kidney disease explain these conditions.

A blockage or swallowed object

Small objects may pass through, but some get stuck and cause a blockage. String and thread are a particular risk, because cats love to chase them. A gut blockage is one of the less common causes, but blockages need to be treated as an emergency.

Poisoning or toxins are another less common cause. Contact your vet if you think your cat has eaten something poisonous.

Signs to look for

Cat diarrhoea is not always obvious. These are the signs to watch for:

Soft, liquid or watery stools
Stools lighter or darker than usual
Straining to pass faeces
Passing faeces more often than normal
Mucus or fresh blood in the stool
Vomiting, loss of appetite or tiredness

It can be hard to spot diarrhoea in a cat that toilets outside. Subtler clues include going out more often than usual, a dirty, smelly or painful-looking bottom, gurgling tummy noises, extra wind, a bloated tummy and a lot of bottom cleaning. Lethargy and an unkempt coat can also be signs.

Home care for mild cat diarrhoea

If your cat has had mild diarrhoea for less than 24 hours and is otherwise fine, you may want to try settling it at home first. "Fine" means bright, active and with no other symptoms.

Give constant access to fresh water, because cats with diarrhoea risk dehydration.
Offer small, bland, regular meals, such as boiled chicken or white fish without skin or bones. Do not feed anything rich or fatty.
Cats need a meat-based diet, so they do not need carbohydrate in a bland diet.
Once your cat is passing solid poo, slowly reintroduce its normal food over a few days.
Let your cat rest, and speak to your vet if it seems very tired or not itself.
Note how often your cat goes, the consistency, and any straining, blood or mucus. This helps your vet narrow down the cause.

A bland diet should not be a long-term solution. Speak to your vet if your cat needs one for more than a few days, or if it refuses to eat.

When to Contact Your Vet

The diarrhoea has lasted longer than 24 hours, has not improved, or has got worse.
Your cat is vomiting, tired, low, off its food, in pain, or has a painful or bloated tummy.
The diarrhoea is watery, explosive or persistent.
There is mucus in the stool. If there is blood, or the stool is black or very dark, ask for an emergency appointment.
Your cat is a kitten, is elderly, or has an underlying health condition. Contact your vet as soon as the diarrhoea starts.
Your kitten is unwell and more than one cat is affected, or a family member is unwell too.

UK sources give slightly different time limits, from 24 hours to a few days. This article uses 24 hours as the cautious line. Cats Protection advises asking for an emergency appointment if diarrhoea comes with lethargy, lack of appetite or vomiting, or if the poo is black or has blood in it. Severe diarrhoea, or diarrhoea with vomiting, can lead to dehydration or serious illness if it carries on.

What your vet may do

Your vet will take a detailed history and examine your cat before deciding whether tests are needed. If the diarrhoea is recent and mild and your cat is bright and eating, they may simply treat the signs and wait.

Tests can include a dietary trial, blood and urine tests, and a faecal sample to look for parasites or harmful bacteria. Some cats need X-rays, an ultrasound scan or an endoscopy.

Treatment targets the cause and supports your cat. A simple, highly digestible diet often helps, and a severely dehydrated cat may need fluids. Vets may also suggest probiotics and products that soothe the bowel. It is rare for a cat with diarrhoea to need antibiotics. In the wrong situation, they can even make diarrhoea worse. Surgery may be needed to remove a foreign body.

The outlook depends on the cause. Many cases resolve completely with the right treatment, and finding the cause of persistent diarrhoea early helps prevent long-term changes.

What not to do

Do not starve your cat. Withholding food can stop the gut healing and may lead to a serious liver condition. If you are unsure, or your cat is vomiting, ask your vet.
Do not give milk or dairy products.
Do not feed leftovers or human foods. Chocolate, onion and garlic are toxic to cats.
Do not give a kitten human medication, because even small amounts can be fatal. For any cat, ask your vet before giving a medicine or supplement.
Do not assume your cat needs antibiotics.

Helping to prevent diarrhoea

Vets Now describes a consistent diet, and limiting your cat's exposure to things likely to cause diarrhoea, as the best form of prevention. Avoid leftovers and human foods, avoid overfeeding, and make any diet change gradually. Moisture-rich wet food and a good water intake can help prevent dehydration and support digestion.

How Pet Med Direct Can Help

You can browse our non-prescription cat digestive support range. Your vet is the best first contact for choosing a supplement, so speak to them before giving one.

If your vet prescribes a medicine, our page on how pet prescriptions work explains how we can help.

Some pet medicines require a valid veterinary prescription. Pet Med Direct can only supply prescription medicines after the prescription has been checked. Always follow your vet's advice and the directions on the medicine label.

Frequently Asked Questions

How long is too long for cat diarrhoea?

Contact your vet if it has not improved within 24 hours, or straight away if your cat is unwell, very young, elderly or has an underlying health condition. If there is blood in the stool, ask for an emergency appointment. UK sources vary slightly, so 24 hours is the cautious line.

Should I stop my cat eating when it has diarrhoea?

Usually not. Vets Now says not to withhold food, and PDSA says there is no need to starve your cat. Offer small, bland meals instead. Blue Cross says to miss the next meal if your cat is vomiting, but that young kittens should never skip a meal, so ask your vet if you are unsure.

Can I give my cat milk?

No. Most cats are lactose intolerant and should not be given any dairy products. Milk can lead to diarrhoea.

Is blood in my cat's diarrhoea an emergency?

Treat it as urgent. Cats Protection advises asking your vet for an emergency appointment if the poo has blood in it or is black. Black, tarry faeces can point to bleeding higher up in the intestine. International Cat Care says a small amount of blood does not usually need emergency attention, but your cat should still be checked, and a large amount does need it.

Can stress cause diarrhoea in cats?

Yes. Stress can cause diarrhoea, and vomiting and diarrhoea are very common in kittens that have recently been rehomed. Even so, ask your vet to check, particularly if it carries on.

Will my cat need antibiotics?

Probably not. It is rare for a cat with diarrhoea to need antibiotics, and in the wrong situation they can make it worse. Your vet may suggest probiotics and products that soothe the bowel instead.

Why does my kitten have diarrhoea?

Causes include stress from rehoming, intestinal parasites, infections, a rapid diet change and swallowed foreign material such as wool or string. Kittens are more at risk of dehydration, so always speak to your vet.

Related Cat Health Guides

Sources and Further Reading

This article was researched from the sources listed above. It is general information for cat owners and is not a substitute for advice from your own vet.

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This article is for informational purposes only and does not constitute veterinary advice.
If you are concerned about your cat’s health, please consult a qualified veterinarian.