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 and less of the old food. This transition allows the pet's digestive system to adjust and lowers the chance of diarrhoea.

According to the PDSA, other potential causes of cat diarrhoea include:

• Viruses, e.g. feline infectious peritonitis (FIP)
• Parasites, e.g. worms, giardia, cryptosporidium
• Imbalances in the microbiome (including bacteria) of your cat’s gut
• 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

What to Do If Your Cat Has Diarrhoea

Assess your cat's behaviour. Do they appear to be feeling well 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, if your cat’s diarrhoea comes and goes frequently, do consider visiting your veterinary practice.

Diarrhoea over a prolonged period (more than a day), as well as diarrhoea accompanied by a significant change in demeanour or other signs, should be treated as an emergency and the cat should be taken to their vet or vet hospital right away. Bright red blood or darker tarry stools are also considered an emergency.

Finally, note the diarrhoea's frequency and appearance so that you can mention it to your veterinarian at your next visit.

How Your Vet Determines the Cause

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

• 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)
• Medication trials (assessing a response to medication)
• Food trials (assessing a response to certain foods)

Treatments & How Nutrition Impacts 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, nutrition plays a key role in managing this condition.

Nutrition plays a significant role in a healthy cat stool. Poor nutrition may lead to chronic (ongoing) diarrhoea, so an assessment of your cat's nutrition will be conducted by your vet. They may recommend switching cat foods as a course of treatment. A lower-fat food or food richer in complex carbohydrates and digestible complex carbohydrates with added fibre may be recommended.

Chronic cases of diarrhoea typically respond to special dietetic foods alongside medications. This category of GI disease is called 'food-responsive enteropathy’. In many cases, your veterinarian will recommend dietetic food for the rest of the cat's life to help maintain proper digestion and promote good stool quality. In cases where food intolerances are a concern, a hydrolysed or novel protein food may be recommended as part of a dietary trial for these cats.  During this time period, the cat can only consume the recommended food, with no treats or other snacks. These trials often last 2-3 weeks for pets with diarrhoea but can last up to 12 weeks if they are also itchy or have problems with their skin or coat.

While cat diarrhoea is unfortunate, with the right treatment and help from your veterinarian your cat can get back to their happy, healthy self.