The most common causes of dog diarrhoea are eating something they should not, sudden diet changes, stress, parasites and infections. Most mild cases settle within a day or two with a bland diet and water. Call your vet the same day for blood, vomiting, lethargy, a dog who will not eat, or diarrhoea in a puppy or older dog.
Diarrhoea in dogs is incredibly common, and it is worrying when it happens. Many cases clear up with simple care at home. Others need a vet quickly, to prevent dehydration or to find an underlying problem. Knowing the difference is what this comes down to.
What are the common causes of dog diarrhoea?
Dog diarrhoea has many causes, but eating something they should not is top of the list. Vets call it dietary indiscretion. A review of acute diarrhoea in dogs lists dietary indiscretion alongside infections, parasites, hormone disease and stress as the main causes.
The usual suspects are raiding bins, eating scraps on walks, or wolfing down something questionable found in the garden. Dogs are natural scavengers, and their stomachs often pay the price.
Parasites are another big group. Roundworms, hookworms, whipworms and single-celled parasites like giardia can all cause loose stools. They are especially common in puppies and in dogs with weaker immune systems.
Bacterial and viral infections, such as Salmonella and Campylobacter, cause their share too. Food intolerances and allergies are less common than many owners think, but can cause long-term tummy trouble.
Rich, fatty food is another trigger. Well-meaning relatives slipping your dog scraps of Christmas dinner can cause a simple upset, or occasionally pancreatitis in dogs, which is far more serious.
When should I call the vet about my dog's diarrhoea?
Call the vet if there is blood in the stool, your dog is vomiting too, refuses food, seems lethargic, or the diarrhoea lasts more than a day or two. Blood, whether bright red or dark and tarry, always needs a vet check. Dog diarrhoea and vomiting together cause dehydration fast, so do not wait.
Check your dog's gums. They should feel slippery, like a wet slide, not tacky like sticky tape. Gently lift the skin over the shoulders and let go. In a well-hydrated dog it snaps straight back. Sunken eyes and skin that stays tented mean dehydration is setting in.
What if your dog has diarrhoea but is acting fine? That is reassuring, and many of these cases do settle at home. But if the loose stools carry on beyond a day or two, they still need attention. Mild cases can escalate, especially if your dog keeps eating things they should not.
Can stress or diet changes really cause dog diarrhoea?
Yes, both stress and sudden diet changes are common causes of dog diarrhoea. The gut and brain are closely linked, so emotional stress can cause real physical symptoms. Moving house, a change in routine, thunderstorms or even excitement can upset sensitive stomachs in dogs.
Healthy dogs can get loose stools from the stress of their owner going away or a new pet arriving. Stress diarrhoea usually settles once the dog adjusts. If it keeps happening, ask your vet about stress colitis.
Dogs' guts like consistency. Switching foods abruptly can cause a short-lived upset. That is why vets recommend changing food gradually over a week or more, mixing in more of the new food each day.
What is the difference between small and large bowel diarrhoea?
Small bowel diarrhoea means large amounts of watery stool, passed less often, while large bowel diarrhoea means small amounts passed very often, usually with mucus or blood. Knowing which type your dog has helps your vet narrow down the cause.
Small bowel diarrhoea is often yellowish or green. It rarely contains visible blood or mucus, and dogs may dehydrate faster because of the volume of fluid lost.
Large bowel diarrhoea comes with straining, sometimes producing just drops of bloody mucus. Yellow mucus diarrhoea in dogs can have several causes and needs a vet check if it carries on. Small bowel problems often respond well to diet and fluids, while large bowel problems may need treatment aimed at inflammation or infection in the colon.
Which home remedies should I avoid for dog diarrhoea?
Avoid human medicines, dairy, fatty foods and long fasting. Never give human medicines like Imodium without your vet's advice. They can mask serious problems or make some conditions worse.
Imodium (loperamide) can be particularly dangerous for Collies and related breeds, because of a genetic difference in how they process some medicines. Even in other dogs, stopping diarrhoea can be the wrong move when the body needs to clear an infection or toxin.
Skip milk and yoghurt, despite old wives' tales. Many adult dogs do not digest lactose well, so dairy can make diarrhoea worse. Rich broths and fatty foods can also overwhelm an upset gut.
Do not starve your dog for long periods either. Many vets now prefer small, bland meals straight away, and long fasting can cause dangerous drops in blood sugar in small breeds and puppies. Some cases that look simple turn out to be gastroenteritis in dogs, which may need proper treatment rather than home care.
Myth: plain white rice alone is the best fix until the diarrhoea stops. Rice on its own is not a complete diet, so add a bland protein such as plain chicken, and move back to normal food or a vet diet within a few days.
How does the gut microbiome affect dog diarrhoea?
The gut microbiome, the community of bacteria in the gut, has a big say in whether diarrhoea settles or keeps coming back. When it is disrupted, vets call it dysbiosis, and it can keep tummy trouble going. Our guide to the dog gut microbiome explains more.
Helpful gut bacteria digest food, make vitamins and support the immune system. Antibiotics, stress, diet changes and illness can all upset that balance, letting less helpful bacteria take over. The imbalance can linger even after the original trigger has gone.
As an MRCVS-registered vet, my view is that supporting the gut helps prevent repeat episodes, but it never replaces finding the cause. Juno Daily for gut health combines Calsporin® Bacillus velezensis (2 billion CFU), a spore-forming probiotic that survives stomach acid, with postbiotics: inactivated Lactobacillus helveticus and Lacticaseibacillus paracasei. It also includes MOS (350mg) and chicory root (250mg), prebiotic fibres that feed helpful bacteria.
It is a daily supplement for a well dog, not a treatment for active diarrhoea. If you are unsure what your dog needs, I usually point owners at the Juno supplement quiz before they buy anything. And once any diarrhoea has been checked and settled, Juno Daily gives steady gut support in one daily scoop.
Frequently asked questions
How long does dog diarrhoea usually last?
A simple upset usually settles within a day or two. If it lasts longer, keeps coming back or your dog seems unwell, see your vet.
How can I tell if my dog is dehydrated from diarrhoea?
Look for dry or tacky gums, sunken eyes and skin that stays tented when you lift it over the shoulders. If you see these, call your vet promptly.
Is a bland diet of chicken and rice always safe for dog diarrhoea?
It is fine for a few days, but it is not a balanced diet long term. Ask your vet for advice, especially for puppies or dogs with other health conditions.
When should I be concerned about yellow diarrhoea in my dog?
Yellow diarrhoea can come from fast transit through the gut, or sometimes from liver or gallbladder problems. If it persists, is severe, or comes with lethargy or vomiting, contact your vet.
Can I give my dog Imodium for diarrhoea?
Not without your vet's advice. It can mask serious problems, and it is particularly risky in Collies and related breeds.
Can regular probiotics prevent future episodes of dog diarrhoea?
They may help some dogs by supporting a healthy gut, particularly where stress or antibiotics are the trigger. They will not prevent every cause, so keep up worming and stop scavenging too.
What is the first aid for a dog with mild diarrhoea?
For an otherwise bright adult dog, offer small, frequent bland meals, such as plain chicken and white rice, with fresh water always available. Watch for blood, vomiting or lethargy and call your vet if they appear.
Is puppy diarrhoea an emergency?
It can be. Puppies dehydrate quickly, and parasites or infections such as parvovirus are possible. Call your vet the same day, and straight away if your puppy is vomiting, flat or will not eat.
This guide is for informational purposes only and does not constitute veterinary advice. Always consult your vet before making changes to your dog's diet, supplement routine, or healthcare plan.
