A single loose stool in a dog that is otherwise bright, eating and drinking normally is common and usually resolves on its own. What decides whether it needs a vet is what accompanies it and how long it lasts.
Go now, do not wait
Any of these makes it urgent regardless of how the dog seems otherwise:
- Blood — either fresh red, or black tarry stool that looks like coffee grounds. Black indicates digested blood from higher up.
- Vomiting as well, especially repeated, or unproductive retching with a hard or swollen belly.
- Pale, white, blue or very dark gums. Press a gum with a fingertip; the colour should return in under two seconds.
- A puppy, a very small dog, or an elderly dog. They dehydrate far faster and have much less reserve.
- Known or suspected access to something toxic, a foreign object, medication, or a rubbish bin.
- Collapse, obvious pain, a hunched posture, or refusing to move.
- Not drinking, or unable to keep water down.
Vet appointment within a day
- Diarrhoea continuing beyond 24 to 48 hours.
- Any diarrhoea with reduced appetite or noticeable tiredness.
- Weight loss, or recurring bouts over weeks.
- A dog with an existing condition, or on medication such as steroids or NSAIDs.
- Straining repeatedly while producing little.
Reasonable to watch at home
An adult dog in good health, with one or two loose stools, still bright, still eating, still drinking, with no blood and no vomiting.
What that looks like in practice:
- Keep water available. Do not withhold it. Withholding food for a short period is sometimes suggested; withholding water is not.
- Feed small, bland, frequent meals rather than the usual portion — plain cooked chicken and rice is the traditional choice, and a vet-formulated intestinal diet is better if you have one.
- Avoid rich treats, dairy, and fatty scraps for several days after it settles.
- Return to normal food gradually over two to three days.
Judging dehydration
Two rough checks, both quick:
Skin tent. Lift the skin between the shoulder blades and let go. It should fall back immediately. Slow return suggests dehydration — though it is less reliable in very thin or elderly dogs.
Gums. They should be moist and pink. Dry or tacky gums are a warning sign.
Neither test replaces a vet's assessment, but both are useful for deciding how urgent a phone call is.
What causes it
The common ones are dietary — a change of food, scavenging, a new treat, or stress. Parasites, infections, medication side effects and food intolerance are the next tier. Chronic or recurring diarrhoea has a longer list and needs investigation rather than home management.
A useful detail for the vet: where in the gut it seems to come from. Large volumes a few times a day suggests small intestine; small amounts very frequently with straining and mucus suggests large intestine. Those point at different causes.
What to bring
- When it started and how many episodes.
- What the stool looks like — a photograph is genuinely useful and vets are used to them.
- Any diet change, new treat, scavenging, or medication.
- Vaccination and worming dates.
This page is about deciding when to call. It is not a diagnosis and it does not replace one — a dog that is unwell needs a vet, not a checklist.
Why the timing of the last meal matters
Vets frequently ask what the dog ate in the previous 24 to 48 hours, and it is not a formality. Dietary causes and infectious causes have different timelines, and the answer often changes what gets investigated first.
A dog that raided a bin, was given a rich treat, or had its food changed abruptly usually shows signs within a day, and improves within a day or two of going back to bland food. An infection or parasite tends to persist regardless of what is fed, and often affects appetite and energy as well.
So the useful thing to record is not just when the diarrhoea started but what changed before it. New treat, new bag of food, a visit to kennels, contact with other dogs, a walk somewhere with standing water — all of those are worth mentioning even if they seem unrelated.
After it settles
Return to normal food over two to three days rather than in one step, and hold off rich treats for a week. A gut that has just been inflamed is easy to set off again, and a second bout starting the day the dog goes back to its usual food is a very common and avoidable pattern.