Dog Diarrhoea: Vet Advice on Causes, Care and When to Worry

Dogs eat fast, sniff everything, and sometimes wolf down things they really shouldn’t. It’s no surprise that diarrhoea is one of the most common reasons dog parents end up at the vet.

In practice, I see it daily: dogs with sudden loose stools, runny poop after a big food change, or diarrhoea that lingers even though they’re otherwise acting completely normal.

This guide covers what causes diarrhoea in dogs, how to treat it at home, what to feed, and when it’s time to troubleshoot with your vet.

If you've got a puppy with runny poop or an adult dog who’s eating and playing normally despite soft stools, exploring these changes matters. The right response early on can save a lot of mess (and a lot of stress).

The appearance of your dog’s diarrhoea can reveal important clues about their digestive health. Soft or unformed stools often follow diet changes, scavenging, or mild stress, while watery, mucus-coated, or oddly coloured poo may suggest parasites, inflammation, or a more serious gut disruption.

Unusual colours like yellow, green, red, or black can point to bile issues, internal bleeding, or fat malabsorption, and should always be flagged with your vet.

For a more detailed breakdown of dog poo types and what they mean, check out our vet-approved dog poo chart with visual cues.

Diarrhoea in dogs occurs when something irritates or disrupts the gut, causing loose or frequent stools, often triggered by diet changes, infections, stress, parasites, or underlying health issues.

Dogs are curious, food-driven, and often aren't exactly picky. That makes their digestive system both surprisingly tough and surprisingly easy to throw off.

Since diarrhoea is a symptom, this means something has disrupted the gut, and the result shows up quickly in their stool.

Diet Changes and Food Sensitivities

Switching diets too fast is one of the most common causes of dog diarrhoea. Even high-quality dog food can cause problems if it’s introduced too suddenly. Some dogs also have sensitivities to proteins like chicken, beef, or grains, which can lead to runny, greasy-looking poo.

Parasites, Infections, and Toxins

Dogs love to sniff, lick, and eat things they shouldn’t. Parasites like Giardia, worms, or bacteria picked up from puddles, parks, or shared bowls can cause quick, watery diarrhoea. Toxins (like spoiled food, chocolate, or human medication) can also trigger sudden, severe symptoms.

Stress and Gut Imbalance

Dogs can develop diarrhoea during or after stressful situations like boarding, vet visits, house moves, or changes in routine. Illness and antibiotics may also disrupt the gut microbiome, reducing good bacteria and leading to soft or irregular stools. Many vets recommend adding a synbiotic supplement, such as Synbiotic D-C Probiotic & Prebiotic Capsules For Dogs & Cats, during recovery to help restore healthy gut bacteria and support more normal stool consistency.

Underlying Conditions

Persistent or recurring diarrhoea could signal something deeper, including:

• Inflammatory Bowel Disease (IBD)
• Pancreatitis
• Food allergies or intolerances
• Liver or kidney disease
• Intestinal cancer (more common in older dogs)
• Pancreatic insufficiency (lack of pancreatic enzyme)

If your dog has persistent diarrhoea but seems fine otherwise, don’t brush it off. Subtle changes in stool can be the first sign of something more complex. Learn more about identifying what's causing your dog's upset stomach with this vet-approved guide.

“In my experience, the gut bounces back fastest when the underlying trigger is identified early: before mild diarrhoea turns into a more complex issue.”

- Dr Lisa Deering

What goes in your dog's bowl makes a big difference to their overall health. The right food is a good first tool to help calm the gut.

Bland, Easy-to-Digest Meals (short-term solution)

For short-term, mild diarrhoea, offer small portions of bland food for no more than 2–3 days. If your dog is otherwise happy, hydrated, and alert, choose one lean protein and combine it with cooked pumpkin (plain, no seasoning):

• Plain cooked chicken (skinless, boneless)
• Steamed white fish
• Cooked pumpkin (plain, no seasoning)

Keep portions small and frequent, avoiding table scraps. Add water or broth to boost hydration. You can also try a vet-approved dog probiotic.

Sensitive Stomach or Limited Ingredient Diets (medium to long-term solution)

Transition to a sensitive stomach diet. Look for:

• Food labelled as limited ingredient or containing a single animal protein (like turkey or chicken)
• Added prebiotics or fibre

Not sure where to start? We’ve got a full guide to the best vet-recommended dog food brands for sensitive tummies.

Natural gut support

• Pumpkin: 1–2 teaspoons (small dogs), up to 2 tablespoons (large dogs)
• Psyllium husk: ¼ teaspoon once daily
• Probiotics: Use a canine-specific formula, especially after antibiotics or travel

Short-term, mild diarrhoea (lasting 1–2 days) can often be managed at home, especially if your dog is still eating, drinking, and acting like their usual self. Alongside a bland diet, here’s what to try:

• Hydration support: Always keep fresh water available. To encourage drinking, offer low-sodium chicken broth (no onion or garlic), or freeze it into ice cubes for dogs who like to chew.
• Probiotics: Use a vet-formulated probiotic made for dogs to help rebalance their gut flora, helpful after antibiotics, stress, or food changes.
• Monitoring stool: Keep an eye on frequency, volume, and consistency. Take photos or note colour and texture changes. They’ll help your vet if things don’t resolve.

While you can’t stop your dog from being curious (or occasionally eating something questionable), many episodes of diarrhoea are preventable with consistent care habits.

Stick to a steady, digestible diet

Dogs thrive on routine. Keep them on a high-quality, vet-recommended food that suits their age and activity level. Avoid switching up meat proteins or brands too frequently. Each change increases the risk of digestive upset.

Stay on top of vaccinations

Parvovirus is a dangerous cause of diarrhoea, especially in puppies. It spreads easily and can be fatal if untreated. Keeping your dog’s vaccinations up to date is essential for prevention, especially during their early months or if they’re around other dogs at parks, kennels, or daycare.

Transition to new foods gradually

Give their gut time to adjust by phasing in new diets over 7–10 days. Changing diets too quickly is one of the most common causes of short-term diarrhoea in dogs.

Use probiotics during stressful periods

Dogs boarding, travelling, moving house, or recovering from illness often benefit from daily gut support. A canine-specific probiotic can help stabilise the microbiome and reduce stress-related diarrhoea.

Stay on top of parasite prevention

Intestinal worms and Giardia are common culprits. Use your vet’s recommended parasite prevention year-round, especially for dogs that socialise at parks or daycares.

Manage scavenging and bin raids

Keep bins secure and supervise walks if your dog’s a notorious scavenger. “Garbage gut” is a leading cause of sudden vomiting and diarrhoea.

Bring water on walks and outings

Drinking from puddles, communal bowls, or lakes can introduce parasites or bacteria. Keep fresh water on hand wherever you go.

Some cases of dog diarrhoea resolve quickly. Others need professional care if the symptoms persist, worsen, or affect your dog’s behaviour.

Book a vet appointment if:

• Diarrhoea lasts longer than 48 hours
• You notice blood, mucus, or a tarry black colour in the stool
• Your dog becomes lethargic, vomits repeatedly, or refuses food
• They’re a puppy, senior, or have a pre-existing health condition

When a dog presents with diarrhoea, the goal is to find out why it’s happening and prevent it from returning.

History and Symptom Review

Your vet will ask about:

• What your dog ate (including treats, human food, or scavenging)
• Any recent food changes, travel, or medication
• Stool appearance and frequency
• Vomiting, bloating, or behaviour changes

Photos of the stool or a clean sample can provide helpful insights to your vet.

Physical Examination

Your vet will check your dog’s hydration, feel their abdomen for discomfort or bloating, assess body condition, and check gum colour and heart rate.

Diagnostic Testing

Depending on your dog’s symptoms and history, your vet may recommend:

• Faecal testing to look for infectious disease,  parasites, Giardia, or bacterial imbalance
• Blood tests to rule out liver, kidney, or pancreatic issues
• Imaging (X-ray or ultrasound) if there’s concern about obstruction or inflammation
• Diet trials to identify food allergies or sensitivities
• Endoscopy or biopsy for chronic or unresponsive cases

For many dogs, diarrhoea improves with a simple food change or short-term support. But when it doesn’t, getting the right diagnosis helps guide effective, lasting treatment.

What causes diarrhoea in dogs?

Dietary indiscretion, parasites, food sensitivities, stress, and illness are all common triggers.

How do I stop diarrhoea in dogs quickly?

Use bland food, small portions, pumpkin or psyllium, and probiotics. Monitor closely.

What home remedy can I give my dog for diarrhoea?

Boiled chicken, plain pumpkin, and a vet-approved probiotic are safe options for mild cases.

My dog has diarrhoea but is acting fine. Should I wait?

You can try home care for 24–48 hours. If it doesn’t improve (or if it comes back) it’s time for a vet visit.

When is diarrhoea in dogs an emergency?

Ongoing diarrhoea with vomiting, blood, or lethargy needs urgent attention.

What to feed dogs with diarrhoea?

Start with a bland diet, then transition slowly to a sensitive stomach formula.

My dog has had diarrhoea with mucus for a week. Is that normal?

No, this suggests persistent gut inflammation. Book an appointment for further testing and treatment.

Diarrhoea is common in dogs and often clears up quickly with a little home care, but it can also be an early warning of something more serious. By watching your dog’s stools, diet, and energy levels closely, you can catch issues before they escalate. If diarrhoea lasts more than a couple of days, or you notice concerning signs like blood, vomiting, or unusual tiredness, it’s best to book a vet visit. With the right support, most dogs bounce back fast and get back to their happy, tail-wagging selves.

This article was written by Dr Lisa Deering