Digestive Health
Why Does My Dog Have Diarrhoea? 7 Common Causes
Few things are as alarming as a mess on the carpet. Here are the seven most common causes UK and US owners run into — and when to stop guessing and call the vet.
Educational content — not veterinary advice
Information on this page is general guidance only and does not replace diagnosis or treatment by a licensed veterinarian. Always work with your vet before making condition-related dietary changes.
1. Dietary indiscretion ("garbage gut")
Scavenging on walks — rotting food, wildlife droppings, dead animals. Supervision and muzzle training help chronic scavengers.
2. Abrupt food changes
Switching kibble without a transition. Move over 7 days: 25/75, then 50/50, then 75/25 before fully swapping.
3. Stress & anxiety
Fireworks, boarding kennels, new family members. The gut-brain axis is real — high cortisol changes stool quality within hours.
4. Parasites
Giardia, roundworm, hookworm, coccidia. Don't guess — ask your vet for a faecal test.
5. Bacterial overgrowth / dysbiosis
An imbalance of gut flora, often after antibiotics. Probiotics and prebiotic fibre are the first line.
6. Food intolerance or allergy
Beef, chicken, dairy, and wheat top the list. An elimination diet with a novel protein confirms it.
7. Underlying disease
IBD, pancreatitis, kidney disease, or (rarely) cancer. Chronic diarrhoea beyond two weeks needs veterinary diagnostics.
Call the vet urgently if you see blood in the stool, repeated vomiting, or lethargy.
Keep reading
The complete guide to dog digestive health →