Cat Diarrhoea: Symptoms, Causes, Treatment & Prevention

If your cat has soft or runny stool, you’re definitely not alone. Cat diarrhoea is one of the most common reasons pet parents call their vet, usually with the same nervous question on repeat: “Why does my cat have diarrhoea?”

The tricky part? Diarrhoea isn’t a disease in itself. It’s a symptom and it can pop up from something as simple as a sudden diet change or as serious as liver disease or intestinal inflammation. So yes, it’s important to pay attention.

We’ll walk you through everything you need to know about cat diarrhoea! What causes it, what it looks like, how to safely treat it at home and how to prevent future messy surprises (your cat and your carpet will thank you).

Understanding Cat Diarrhoea

At its core, diarrhoea in cats simply means frequent, soft, liquid or unformed stools. It can affect either:

• The small intestine, resulting in large volumes of watery stool and possible weight loss.
• The large intestine, leading to smaller amounts of stool but more urgency, mucus and sometimes blood.
  
  

While one loose poo isn’t usually a crisis, ongoing diarrhoea can lead to dehydration, nutrient loss and declining immune function. Kittens, senior cats and cats with pre-existing health issues are more vulnerable and can become unwell quickly.

Symptoms of Diarrhoea in Cats

Stool Characteristics

What your cat leaves in the litter tray can tell you a lot about their internal health.

• Consistency: watery, mushy, pudding-like
• Colour:
  • Yellow = bile imbalance
  • Green = intestinal inflammation
  • Black = digested blood
  • Red = fresh blood
  • Smell: unusually foul or metallic
• Extras: mucus, visible worms or odd textures
  
  

Litter Box Behaviour

Changes in how your cat uses the litter box can be just as telling as what’s inside it.

• More frequent trips
• Urgency or rushing
• Accidents outside the tray
• Straining, vocalising or discomfort while pooping
  
  

Systemic Symptoms

Diarrhoea doesn’t always act alone. Watch closely for:

• Vomiting
• Loss of appetite
• Low energy or hiding
• Dehydration (dry gums, skin tenting, sunken eyes)
• Weight loss over time
  
  

If any of these appear alongside diarrhoea, your cat may need vet attention sooner rather than later.

Causes of Cat Diarrhoea

There are many reasons cats develop diarrhoea, some benign, some more concerning. Here’s a breakdown of the most common causes.

Dietary Causes

Food is one of the biggest players in feline tummy troubles.

• Sudden diet changes: switching foods too quickly shocks the digestive system.
• Eating spoiled or fatty foods: including raiding the bin.
• Food intolerances or allergies: such as dairy, beef or grains.
  
  

Parasites & Infections

Even indoor cats aren’t completely in the clear.

• Intestinal parasites: roundworms, hookworms, tapeworms, Giardia
• Bacterial infections: Salmonella, E. coli
• Viral infections: feline panleukopenia, feline coronavirus
  
  

These are especially worth investigating in kittens or outdoor explorers.

Stress & Environmental Changes

Stress hits the gut hard (thanks, gut-brain axis)

• Moving house
• New pets or babies
• Boarding or travel
• Loud renovations
• Changing household routines
  
  

A stressed cat can develop cases of acute diarrhoea overnight.

Medical Conditions

Sometimes diarrhoea signals a deeper issue:

• Inflammatory Bowel Disease (IBD)
• Hyperthyroidism
• Liver disease
• Kidney disease
• Pancreatitis
• Diabetes
• Intestinal lymphoma, especially in older cats
  
  

Chronic diarrhoea or weight loss always warrants veterinary assessment. In rare cases, foreign-body ingestion or unusual toxins can trigger severe gastrointestinal damage, (Cat Specialist Services).

Medication & Toxins

Certain substances can upset the gut or irritate the intestines.

• Antibiotics altering intestinal bacteria
• NSAIDs, steroids, cancer medications
• Ingesting toxic plants (like lilies) or household chemicals

When to Worry: Signs You Need a Vet

Seek veterinary advice if your cat shows:

• Diarrhoea lasting more than 48 hours
• Blood in the stool (red or tar-black)
• Vomiting alongside diarrhoea
• Lethargy or refusal to eat/drink
• Any signs of dehydration
• Symptoms in kittens, seniors or chronically ill cats
• Frequent or recurring diarrhoea

Treating Cat Diarrhoea at Home

If your cat is otherwise bright, alert, eating and drinking, you can begin safe, vet-approved home care. Here’s a step-by-step guide.

Start With a Bland Diet

Give the digestive system a small "holiday" by offering plain, simple foods.

• Cooked chicken breast
• Small amount of white rice
• Plain pumpkin purée (1–2 teaspoons)
• Feed small, frequent meals rather than large portions
• Avoid dairy, raw meats, fish and commercial treats until normal stools return

Hydration Is Key

Diarrhoea drains moisture quickly! Keeping your cat hydrated is essential.

• Fresh water available at all times
• Low-sodium chicken broth for picky drinkers
• Pet-safe electrolytes 

Add a Probiotic Supplement

A high-quality probiotic helps restore good intestinal bacteria and can reduce the duration of diarrhoea.

Try a daily probiotic such as cat probiotics – a gentle, vet-formulated powder that mixes easily with food.

Benefits include:

• Supporting microbiome balance
• Easing inflammation
• Strengthening the immune system
• Promoting smoother digestion over time
  
  

Probiotics aren't just for sick days, they work wonderfully as a preventative during diet transitions, boarding, travel and after antibiotics.

Avoid Human Medications

Never give cats your own pharmacy products. Avoid any human gut medication as cats process drugs differently and these can be toxic.

Monitor Stool & Symptoms

Keep an eye on:

• Frequency of stools
• Colour and consistency
• Appetite and hydration levels
• Energy levels
  
  

Improvement within 24-48 hours is a good sign. Worsening symptoms are a signal to call your vet.

Veterinary Diagnosis & Treatment

If diarrhoea is severe, ongoing or accompanied by other symptoms, your vet may run several diagnostic tests.

What Vets May Do

• Full physical examination
• Hydration check
• Faecal exam (including microscopy or PCR testing for parasites/bacteria)
• Blood tests (liver, kidney, thyroid levels)
• Imaging such as X-rays or ultrasound, especially for chronic diarrhoea or foreign object concerns
  
  

Typical Vet Treatments

Based on the diagnosis, treatment may include:

• Subcutaneous or IV fluids
• Prescription dewormers
• Probiotic pastes
• Prescription gastrointestinal diets
• Antimicrobials like metronidazole
• Anti-nausea medication
• Steroids for IBD
• Support for liver disease, such as liver support for cats

Preventing Future Diarrhoea

Once your cat’s tummy settles, prevention becomes your best friend!

Diet Management

Keep nutrition consistent and high-quality.

• Transition new foods slowly over 7–10 days
• Avoid table scraps, especially dairy
• Choose a nutritionally balanced diet that suits your cat’s needs
  
  

If you’re shopping for additional daily support, you can explore Petz Park’s cat supplements or browse their wider range of pet supplements.

Gut Health Support

Daily probiotics support a resilient microbiome, crucial for cats prone to digestive wobbliness.

A daily sprinkle of cat probiotics can help maintain healthy intestinal bacteria and reduce the risk of flare-ups.

Parasite Prevention

• Regular deworming on your vet’s schedule
• Consistent flea control (important for tapeworm prevention!)

Stress Reduction

Cats don’t always love change but a few small adjustments help:

• Predictable feeding routines
• Quiet hiding spots
• Slow introductions to new pets or environments

Monitor Health

• Maintain routine vet check-ups
• Keep the litter tray clean to spot abnormalities early
• Watch for changes in stool colour, frequency or shape

Cat diarrhoea is stressful! No one likes seeing their feline friend uncomfortable (or scrubbing the carpet for that matter). The good news is that most cases are short-term and easily managed with the right care, whether that’s a bland diet, hydration or adding gut-support supplements.

Remember:

• Watch for red-flag symptoms
• Treat early with gentle home care and visit your vet when necessary
• Support digestive health daily to prevent future flare-ups
  
  

If you’re looking for natural, vet-formulated ways to care for your cat’s tummy long-term, explore Petz Park’s cat probiotics. They’re simple additions that help keep the gut (and your cat) happy.