Managing Cat Diarrhoea: Causes, Symptoms & Treatment

Causes of Cat Diarrhoea

There are many causes of diarrhoea. Often it occurs when a cat eats something unusual or when their meal plan changes abruptly. When switching from one kind of cat food to another, it's best to transition slowly over a week, gradually mixing in more of the new food with less of the old food. This transition allows the pet's digestive system to adjust and lowers the chance of diarrhoea.

Other potential causes of cat diarrhoea include:

• Viruses, e.g. feline infectious peritonitis (FIP)

• Parasites, e.g. worms, giardia, cryptosporidium

• Imbalances in the microbiome in your cat’s gut

• Stress

• Dietary indiscretion (eating something they shouldn’t have!)

• A gut blockage

• Food intolerances/allergies

• Inflammatory bowel disease

• Antibiotics and other drugs

• Poisoning/toxins

• Gut infections, e.g. salmonella, campylobacter

• Pancreatitis

• Liver disease

• Kidney disease

• Hyperthyroidism

• Cancer

Can I treat my cat’s diarrhoea at home?

If your cat seems bright and active, they may just have a ‘bug’ or may have eaten something that didn't agree with them. In these cases, you don’t need to panic. Encourage drinking and ask your vet for a highly digestible ‘recovery’ food to feed them for a few days until all is normal again. A veterinary exam can help rule out any other signs of illness. Many cases of cat diarrhoea do resolve on their own. If your cat will eat wet food, this is a good way to keep them hydrated.

Never give your cat medication that has not been prescribed for them, and never give medication meant for other species, especially dogs and humans. 

Don’t give your cat treats, dairy products, or rich foods until they’re fully recovered.

When is cat diarrhoea an emergency and when should I see a vet?

Does your cat appear to be feeling sick or acting more tired than normal? Do they have a poor appetite or any other symptoms that stray from their norm? Are they also vomiting? If a case of cat diarrhoea is an isolated incident that resolves spontaneously in less than a few hours and doesn't involve other symptoms, it's generally not treated as an emergency. 

However, you should consider cat diarrhoea an emergency if:

• your cat is lethargic
• your cat is also vomiting
• your cat has no appetite
• your cat seems dehydrated
• your cat’s diarrhoea has blood in it or is very dark or black

Although not an emergency, you should also see your vet if:

• the diarrhoea lasts more than 24 hours, even if your cat is bright and active
• the diarrhoea comes and goes for any length of time
• your cat is a kitten or an older cat, as they can become dehydrated faster than a normal adult cat

How Your Vet Determines the Cause

Vets may use several tools to determine the cause of your cat's diarrhoea, including:

• The cat's medical history

• A physical examination

• Basic lab work (e.g. blood work, faecal exam)

• Radiography (e.g. x-ray)

• Sonography (e.g. ultrasound)

• Gastrointestinal function tests (blood tests)

• Endoscopy/colonoscopy and biopsy (to retrieve a tissue sample from the digestive tract)

• Medication trials (assessing response to medication)

• Food trials (assessing response to certain foods)

Treatment of cat diarrhoea

Treating diarrhoea depends on its underlying cause. There are many available treatments for diarrhoea that may be recommended by your vet depending on a variety of factors. However, whatever the underlying cause, nutrition plays a key role in managing this condition. Diarrhoea falls into 3 general categories outside of the self-limiting cases we mentioned before:

1. Food-responsive diarrhoea can be further divided into:.
   • Adverse food reactions – allergies and intolerances. Cats with adverse food reactions are usually given a hydrolysed diet or a novel protein diet. These will usually need to be fed for life.
   • Diarrhoea due to a microbiome imbalance. Many cats respond to a simple change of diet to one which has high levels of prebiotic fibres to nourish the ‘good bacteria’ in the gut and promote gut health. These diets also usually have high levels of omega three to reduce inflammation and are highly digestible.
2. Steroid-responsive diarrhoea. This is also called immunosuppressant-responsive diarrhoea or inflammatory bowel disease (IBD). As it sounds, these cases often need medication as well as a high quality diet to get a response.
3. Underlying disease. If your vet finds that your cat has an underlying medical problem like kidney disease or hyperthyroidism, they may prescribe other forms of treatment. Sometimes, this also includes a change of diet, as many organ diseases can be helped with therapeutic diets..

While cat diarrhoea is never pleasant for you or your cat, with the right treatment and help from your vet your cat can get back to their happy, healthy self.

Cat Diarrhoea FAQs

What causes diarrhoea in cats?

A number of things, including food allergies, stress, infections, parasites and dietary indiscretion.

When is cat diarrhoea an emergency?

In situations where:

• your cat is lethargic
• your cat is also vomiting
• your cat has no appetite
• your cat seems dehydrated
• your cat’s diarrhoea has blood in it or is very dark or black

Is wet food better for cats with diarrhoea?

Yes. Diarrhoea can quickly cause dehydration, especially in kittens and older cats. Wet food is a great way to keep cats hydrated.

Can stress cause diarrhoea in cats?

Yes. Stress can cause many problems in cats including vomiting, diarrhoea, cystitis and over-grooming.

Reviewed by Karen Shenoy, DVM and Emma Milne, BVSc FRCVS