Dog Diarrhoea: When to See a Vet
Blood in the diarrhoea, constant watery diarrhoea, vomiting too, a painful belly, or a very young or old dog? Phone your own vet or the nearest emergency vet now. Find an emergency vet. Might it have eaten something? My dog ate something.
Quick answer
PDSA says most mild cases resolve within 24 to 48 hours, but to contact your vet as soon as possible if diarrhoea lasts more than 24 hours, contains blood or mucus, is severe or constant and watery, or if your dog is very young or very old, has another health condition or takes anti-inflammatory medicine, seems unwell, is vomiting, eating less, lethargic or in pain.
From PDSA and VCA. Not veterinary or financial advice. Worried about your pet now?
On this page (6 sections)
Contact your vet as soon as possible if
- The diarrhoea has lasted more than 24 hours, or soft stools continue beyond 24 hours.
- There is blood and/or mucus in it, or it is severe, constant and watery.
- Your dog is very young or very old, has another health condition, or is on medication, especially anti-inflammatories (NSAIDs).
- Your dog seems unwell, is eating less, vomiting or lethargic.
- Your dog has a painful belly, such as yelping when picked up or standing in a "prayer position".
Source: PDSA Pet Health Hub, Diarrhoea in dogs. VCA also lists multiple episodes of soft or watery stool and blood in the stool as reasons for urgent care, and an emergency hospital if a pet seems severely ill or struggles to stand. Source: VCA Urgent Care, Diarrhea or vomiting.
Mild cases
PDSA says most cases are mild and resolve within 24 to 48 hours. For an adult dog that is otherwise well and has had diarrhoea for less than 24 hours, it describes settling the stomach at home first, with plenty of water available. Its page sets out how; it does not advise fasting very young or very old dogs or dogs with another illness. If symptoms pass 24 hours, or your dog seems unwell, contact your vet. Puppies are more at risk, so PDSA advises seeking advice for a puppy with diarrhoea. Source: PDSA Pet Health Hub, Diarrhoea in dogs.
Common causes
PDSA lists eating something rich, fatty or unfamiliar, a sudden change of food, food allergies, infections such as parvovirus, giardia, Salmonella or Campylobacter, worms, haemorrhagic gastroenteritis, colitis, a gut blockage, inflammatory bowel disease, pancreatitis, liver disease and exocrine pancreatic insufficiency. If your dog may have eaten something it should not have: my dog ate something. Source: PDSA Pet Health Hub, Diarrhoea in dogs.
What to tell the vet
When it started, how often, what it looks like (colour, blood, mucus, how watery), whether your dog is eating, drinking and vomiting, any change of food or anything it may have eaten, and any medicines. A photo or a fresh sample in a clean container can help; ask the practice first.
Questions people ask
When should I take my dog to the vet for diarrhoea?
PDSA says to contact your vet as soon as possible if it lasts more than 24 hours, has blood or mucus, is severe or constant and watery, or if your dog is very young or very old, unwell, vomiting, eating less, lethargic or in pain.
How long does dog diarrhoea last?
PDSA says most mild cases resolve within 24 to 48 hours. Contact your vet if it goes on beyond 24 hours or your dog seems unwell.
Is diarrhoea in puppies more serious?
PDSA says diarrhoea in a puppy can be more serious and advises seeking advice from your vet.
Is blood in my dog's diarrhoea an emergency?
PDSA lists blood and/or mucus as a reason to contact your vet as soon as possible, and VCA lists blood in the stool as a reason for urgent care.
Sources
- PDSA Pet Health Hub, Diarrhoea in dogs, read 7 November 2026.
- VCA Urgent Care, Diarrhea or vomiting, read 7 November 2026.
Related pages
Dog vomiting: when to worry, switching food safely, my dog ate something and pet emergency: what to do now.