Dog with diarrhoea — when to worry
A bright dog with mild loose stool can be managed at home for 24 hours with bland food; blood, repeated episodes, lethargy, or any puppy/senior needs a same-day vet call.
Recognise the signs
- Loose, soft, or watery stool
- Mucus or jelly-like coating (typical colitis pattern)
- Blood — fresh red streaks or 'raspberry jam' watery red
- Increased frequency, straining, or urgency
- Vomiting alongside diarrhoea
- Lethargy, off food, painful belly
- Dehydration — sunken eyes, tacky gums, slow skin tent
First aid steps
- Withhold food for 4–6 hours (skip in puppies under 6 months — they cannot afford to fast).
- Offer small amounts of water every 30 minutes.
- After 4–6 hours offer a small bland meal — boiled chicken and white rice, or boiled white fish.
- Continue small bland meals every 3–4 hours for 24 hours.
- Gradually reintroduce normal food over 3–5 days.
- Photograph the stool — vets find this genuinely useful.
Do NOT
- Do not give human anti-diarrhoeals (Imodium, Pepto-Bismol) without vet advice — Pepto-Bismol contains salicylates toxic to dogs, Imodium is unsafe in some breeds (Collies and related, MDR1 mutation).
- Do not give milk to settle the stomach — most dogs are mildly lactose-intolerant.
- Do not feed fatty mince, sausage, or scrambled egg with butter.
- Do not skip food in a puppy under 6 months.
- Do not delay if there is any suspicion of toxin or rodenticide ingestion.
When to phone the vet immediately
- Watery red 'raspberry jam' diarrhoea — possible HGE/AHDS
- Black, tarry stool
- Vomiting alongside diarrhoea, especially repeated
- Pale gums, lethargy, collapse, dehydration
- Puppy under 6 months — parvovirus risk, fluid loss is fast
- Senior dog or any dog with chronic illness
- Diarrhoea persisting more than 48 hours
- Known or suspected rodenticide or toxin access
Signs that can usually wait for a routine appointment
- Single soft stool or one loose episode in a bright, eating, drinking, playful dog with no other signs can usually be monitored at home with bland diet for 24 hours.
Common causes
- Dietary indiscretion — scavenged food, sudden diet change, fatty leftovers
- Stress colitis — kennelling, travel, new home, fireworks
- Worms or other parasites (giardia, hookworm)
- Bacterial infection — Campylobacter, Salmonella
- Viral infection — parvovirus (puppies, unvaccinated dogs)
- Pancreatitis (often after fatty food)
- Inflammatory bowel disease
- Foreign body partial obstruction
- Toxin exposure
What the vet will need to know
- Frequency, volume, and appearance of stool
- Presence of blood or mucus
- Other signs — vomiting, appetite, energy
- Recent diet changes, scavenging, or new treats
- Worming and vaccination status (especially in puppies)
- Any possible toxin access
- Photo of the stool
Aftercare
- Bland diet for 3–5 days, gradual return to normal food over 3–5 more days.
- Probiotic paste from the vet often shortens recovery.
- Fresh stool sample test if infection suspected — pots provided by the vet.
- Repeat sample 7–10 days later if a parasite was identified.
- Investigate persistent or recurring cases — bloodwork, ultrasound, faecal panel.
Prevention
- Bin-proof kitchens; supervise off-lead walks for scavenging.
- Transition diets over 5–7 days.
- Stay current on worming and vaccination.
- Manage stress at known triggers.
- Avoid fatty leftovers and human treats with rich sauces.
Breed-specific notes
- Small breeds (Yorkshire Terrier, Maltese, Schnauzer) appear over-represented in HGE/AHDS.
- German Shepherds and Boxers higher incidence of inflammatory bowel disease.
- Collies and related breeds (Australian Shepherd, Shetland Sheepdog) carry MDR1 mutation risk affecting some medications.
Frequently asked questions
How long is too long to wait with dog diarrhoea?
A bright, eating, drinking adult dog with mild loose stool can usually be monitored at home for 24 hours. Beyond that, or at any point if blood, vomiting, lethargy, or pale gums appear, contact the vet. Puppies, seniors, and chronically ill dogs need contact much sooner — within hours.
What is 'raspberry jam' diarrhoea?
A distinctive red, watery, foul-smelling diarrhoea seen in haemorrhagic gastroenteritis (HGE), now usually called acute haemorrhagic diarrhoea syndrome (AHDS). Dogs can dehydrate fast and need IV fluids. This is a same-day emergency — phone the vet immediately.
Can I give my dog Imodium?
Imodium can mask serious problems and is unsafe in some breeds. Some vets prescribe it in specific cases at specific doses, but it should never be given without vet advice — particularly if the dog is a Collie, Australian Shepherd, or related breed where the MDR1 gene mutation can cause severe reactions.