Diarrhoea in dogs: What do I need to know?

Diarrhoea happens to every dog (and let’s be honest, owners too). It simply means poop that’s softer than usual—anything from soft-serve ice cream to an unformed mound, porridge-like, or completely liquid.

If it’s a one-off and your dog seems bright and active, most owners – and even most vets – won’t be too concerned. But if it happens twice, or you spot other signs, it’s worth paying closer attention.

Need a reference? We’ve put together a handy dog poo chart to help you figure out what’s normal – and what’s not.

What are the causes of diarrhoea in dogs?

The list of potential causes is longer than a giraffe’s neck – but here are some of the most common reasons why your dog might have diarrhoea:

• Dietary change or dog food allergies – Sudden changes, new treats or scraps from the table can upset their stomach
• Dietary indiscretion – Eating something they shouldn’t, whether fresh or foul. 
• Toxins – Ingesting plants, chemical, medications or other harmful substances.
• Foreign bodies – From bones to toys to bits of fabric
• Parasites – Not just worms, but also microscopic ones like Giardia
• Infections – Bacterial, viral or fungal
• Organ disease or inflammation – Including issues with the liver, kidneys or pancreas
• Medications – Some treatments can irritate the gut
• Stress or overheating – Both can impact digestion and gut function, so it's important to recognise the signs of stress in dogs.

Without proper care, even mild cases can progress to more serious issues, including haemorrhagic diarrhoea or gastroenteritis. Read about what to do if your dog has diarrhoea. 

Types of diarrhoea in dogs 

Diarrhoea in dogs is often described as either small intestinal or large intestinal, and knowing the different can help you describe your pup’s problem more accurately to a vet. 

Small intestinal diarrhoea

This starts higher up in the digestive tract. Dogs with this type can often wait until they’re outside – then pass a large amount of loose stool in one go. There’s usually less straining, and you’re less likely to see mucus or visible blood.

Large intestinal diarrhoea

This comes from lower down in the gut. The urge to go can be sudden and frequent, which may lead to accidents in the house. You might notice your dog straining, passing small piles – or puddles – of poo, often with fresh red blood or mucus.

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What does the colour of dog diarrhoea mean?

Diarrhoea often comes in different colours and consistencies, and this can help give us clues as to the cause of the diarrhoea:

Watery yellow: If your dog's stool is a watery, yellow mustard colour, it can suggest digestive issues, either that the enzymes meant to break down food aren't being produced in sufficient quantities or that food is moving through the digestive tract faster than usual. Watery yellow diarrhoea leads a vet to consider liver and gallbladder problems. 

Watery orange: Orange watery dog stools could mean your dog has eaten something with an orange pigment, such as carrots; however, persistent orange stools could signal poor fat digestion or biliary inflammation. 

Mucus: Diarrhoea stools with lots of mucus look almost jelly-like with a clear, yellow slimy film. Persistent or heavy mucus stools can point to inflammation of the large intestine, food allergies or internal parasites such as worms. 

Black/Tarry: Stools will appear shiny, dark and sticky, usually extremely foul-smelling, and will resemble a tar-like substance. Black stools are worrying as they are a sign of melena, which is digested blood from further up the digestive tract. Problems such as stomach ulcers can lead to black tarry stools. If your dog has black/tarry stools, it is a medical emergency; contact your veterinarian as soon as possible. 

How long does diarrhoea last in dogs?

Diarrhoea in healthy adult dogs typically lasts one to three days. If your dog is acting completely normal, and is eating, drinking and otherwise has normal energy levels, you can treat diarrhoea for up to 3 days at home. Common home remedies include offering small amounts of water and small frequent meals of a bland digestible diet. Examples of an easy to digest food include chicken and rice, or your vet will stock prescription digestive upset foods to help with diarrhoea. 

If the diarrhea lasts longer than 3 days and any of these other symptoms you should contact your veterinarian for a check up: 

• Blood in the stool/tar like appearance to the stool
• Vomiting
• Lethargy, or weakness
• Belly pain - stretching their legs out, looking at their belly, not able to get comfortable
• Behaviour changes- biting or growling if trying to look or touch at your dogs belly
• Bloated belly or loud gurgling sounds from the belly 

It's important to note that puppies, senior dogs or dogs with pre existing health conditions should be seen by a vet within 24 hours as they experience dehydration faster than other dogs.

Some dogs will have diarrhoea for longer than a week, and at this point, it is considered chronic diarrhoea. This can lead to issues with absorption of vital nutrients and vitamins and lead to weight loss. It’s important to contact your vet even if your dog looks well in themselves as chronic diarrhoea usually requires medical treatment to resolve.

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What are the treatments for diarrhoea in dogs?

One of the simplest ways to stop diarrhoea in an otherwise fit, healthy dog is a short break from food. Fasting for 12-24 hours gives the gut a chance to clear out any irritants before more food is added to the mix. But remember—the gut relies on nutrients from what’s passing through to heal and function properly, so fasting for too long can actually delay recovery. We’ll cover what to feed a little lower down.

Veterinary treatment is often supportive and focused on managing symptoms, such as fluids, gut protectants, binding agents, and prescription diets. However, if a clinical examination raises concerns about an underlying cause or potential complications, your vet may recommend further tests. This allows treatment to be more targeted, addressing specific causes such as infection, parasites, or organ disease, and helping to manage any complications more effectively. 

What to give a dog with diarrhoea

Because diarrhoea is so common, there are some excellent pet-specific products designed to help you manage it at home. One widely used option is a probiotic binding paste. It helps by soaking up excess water in the gut and supporting a healthy balance of good bacteria – giving your dog’s digestion a helping hand while things settle. Learn more about how to support your dog's digestion.

What not to give a dog with diarrhoea

If your dog has diarrhoea there are certain foods that can make the diarrhoea a whole lot worse, meaning more cleaning for you, and more stomach upset for your dog. 

When your dog is having loose stools or diarrhoea, you should avoid feeding fatty or rich foods such as bacon, butter and oils. These types of food put a strain on the function of the pancreas and liver, prolonging the duration of the diarrhea.

 Most dogs are lactose intolerant so do not feed foods with dairy in it, as this will worsen diarrhoea. 

Firm or hard dog treat chews and bones can be abrasive and difficult for the gut to digest so put away the dog treats of all types until your dog is completely clear from diarrhoea symptoms for at least 48 hours. 

Whilst you may think that human medications may help your dog with their diarrhoea, under no circumstances should you give your dog any human anti-diarrhoeal medications such as pepto-bismol or Imodium. These medications can contain toxic ingredients, and may harm your pet. Always use medications under the advice of a veterinarian, and make sure the medications are licensed for use in dogs. 

What to feed a dog with diarrhoea

A bland diet is often recommended for dogs with diarrhoea – and with good reason. When the gut is inflamed and moving too quickly, it can struggle to process normal food or full-sized meals.

• Home-cooked diets 
  A classic choice is boiled, skinless, boneless chicken mixed with an equal amount of cooked white rice. If your dog is allergic to chicken, boiled egg is a good alternative.
  
• Prescription diets
  Gastrointestinal diets are a lower-effort option that’s especially useful for dogs with food sensitivities or specific nutritional requirements. 
  
• Small portions
  After a 12-24 hour fast, start with very small amounts—a teaspoon for small dogs and up to a serving spoon for a giant breed.
• Little and often
  Feed small amounts every 2-4 hours. This helps avoid overwhelming the gut while it recovers.
• Gradual return to normal
  Stick to the bland diet for 3-5 days, gradually increasing portion size if things start to settle. Once your dog’s poos are back to normal, you can slowly transition them back to their regular food.

Read our guide on what to feed a dog with diarrhoea.

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How to keep my dog hydrated?

It’s important to keep your dog hydrated if they have diarrhoea. Water makes up 60%-70% of a dog's body weight, and dehydration can have serious consequences for the body. Significant fluid or water loss can compromise organ function, deplete electrolytes, and eventually trigger hypovolemic shock. Whilst most cases of diarrhoea will not reach that level of severity, there are cases that need hospitalisation for intravenous fluids to stop them getting dehydrated.

Signs of dehydration in dogs include dry gums, tongue or lips, small amounts of urine, actively seeking water and a ‘skin tent’- this is where you raise your dogs skin and it stays up rather than drops back down to its normal position on the body. 

You can help keep your dog hydrated at home with a few easy tricks: 

• Always offer small, frequent amounts of fresh water in their bowl.
• Offer vet-approved, dog-safe electrolytes which help with water retention and fluid distribution throughout the body.
• You can try small ice chips to see if your dog is interested, especially in summer.
• Avoid syringing water into your dog. This can lead to water accidentally entering the airway, which can lead to aspiration pneumonia (bacterial infection in the chest) 

While it's tempting to give your dog as much water as possible to prevent dehydration, it isn’t a good idea. Too much water can lead to problems such as vomiting, and redistribution of electrolytes in the body, leading to neurological issues. Balance is everything, and if you are unsure or think your dog is dehydrated, your vet is the person to help advise on safe oral fluid intakes. 

What to do about bloody diarrhoea in dogs

It’s not unusual to see a bit of blood in diarrhoea. Straining often results in a few streaks or drops of blood on the surface of a poop. 

However, if you notice blood mixed into the diarrhoea, this needs to be taken more seriously. It means there’s more significant inflammation in the gut that could allow bacteria to cross into the bloodstream. In these cases, your dog should see the vet. Treatment might include antibiotics, but not always.

Puppy diarrhoea

Puppies go through a lot of changes that can trigger diarrhoea – from weaning and diet transitions to worming treatments, settling into a new home or starting walks. They’re also naturally curious, which means they’re more likely to chew or swallow things they shouldn’t.

While serious causes like parvovirus are always a concern, even mild diarrhoea can escalate quickly in puppies. They can become dehydrated much faster than adult dogs, and it’s not usually recommended to withhold food – especially for very young or toy breeds. Read our guide on how often your puppy should poop. 

If your puppy still seems bright, playful and curious, you can offer tiny portions of bland food. But if the diarrhoea lasts more than 12-24 hours – or you notice other worrying signs – it’s best to contact your vet.

Diarrhoea in old dogs

Older dogs can be more prone to mild upsets, and sometimes diarrhoea is linked to an underlying health issue. Medication is another complicating factor. For instance, NSAIDs (non-steroidal anti-inflammatory drugs), often used for arthritis, may need to be stopped during an episode of diarrhoea.

If your senior dog has an existing condition or takes regular medication, it’s a good idea to call your vet at the first sign of diarrhoea. They’ll be able to guide you on the best next steps and help avoid any complications.

How to prevent diarrhoea in dogs

While some causes of diarrhoea are outside your control, there are simple steps you can take to support healthy digestion in dogs and help reduce the risk of tummy upsets:

• Make any diet changes gradually – ideally over 5-7 days
  
• Store food properly to keep it fresh – and out of reach
  
• Keep food and water bowls clean, and always offer fresh water
  
• Puppy-proof your home – secure bins, store medicines safely and choose non-toxic plants and cleaning products
  
• Stay on top of routine care like vaccinations and worming

Small daily habits can go a long way in helping your dog maintain a happy, healthy gut.

When to consult your vet

Diarrhoea in dogs is very common – and in many cases, it clears up without a trip to the vet. But there are times when it’s best to get professional advice:

• Two or more episodes that are getting softer or more watery
  
• Blood mixed into the diarrhoea – especially if it looks like raspberry jam
  
• Diarrhoea with signs like lethargy, a bloated or tense tummy, or signs of pain
  
• If your dog is very young, very old or has existing health conditions
  
• Loose stools that continue or worsen despite fasting or a bland diet

If you’re unsure, it’s always okay to call your vet. A quick chat could offer peace of mind – or help catch something more serious early.

At the clinic, your vet will usually check for signs of dehydration, tummy tenderness or a raised temperature. From there, they’ll guide you on the best course of action – whether it’s at-home care or further tests and treatment.