Diarrhoea in dogs: causes, home care and when to worry

Diarrhoea is among the most frequent reasons dog owners call their vet. A single loose stool in an otherwise bright and alert dog is rarely cause for alarm — dogs are indiscriminate eaters, and the gut usually self-corrects. The challenge is recognising when diarrhoea signals something more serious.

Veterinarians classify diarrhoea by origin: small-intestinal (large volume, infrequent, often with weight loss) or large-intestinal (small volume, frequent, often with mucus or straining). Both can be acute (sudden onset, under two weeks) or chronic (persisting beyond two to three weeks). Acute cases are far more common and usually self-limiting.

Common triggers include dietary indiscretion (raiding the bin, eating rich table scraps), a sudden change in food, stress, intestinal parasites, viral or bacterial infections, and reactions to medications such as antibiotics. In tropical climates like Singapore, year-round parasite exposure — especially roundworm, hookworm and Giardia — means parasites should be on the short list for any recurring case.

When you can usually manage at home

A healthy adult dog with mild, watery-but-not-bloody diarrhoea, normal energy levels, no vomiting and a good appetite can often be managed conservatively for 24–48 hours. The key principles: keep fresh water available at all times, withhold food for 12–24 hours if your vet advises (this is less common now; many vets prefer a bland diet immediately), then offer small portions of a bland, easily digestible diet.

• Bland diet options: plain boiled chicken (no skin, no seasoning) with white rice; or a commercial intestinal diet prescribed by your vet
• Feed small amounts (roughly half the normal portion) every 4–6 hours for 2–3 days
• Gradually transition back to the regular food over 3–5 days once stools firm up
• Ensure continuous access to fresh water — dehydration is the main risk
• Probiotics formulated for dogs (e.g. containing Enterococcus faecium) may shorten duration; ask your vet for a recommendation

When to see a vet within 24 hours

• Diarrhoea lasting more than 48 hours despite bland diet
• Any vomiting alongside loose stools, especially if repeated
• Lethargy, decreased appetite or a dog that is not acting normally
• A puppy, senior dog, or dog with a known condition such as Addison's disease or inflammatory bowel disease
• Mucus or small amounts of fresh blood in the stool (can indicate large-bowel inflammation)
• Diarrhoea returning soon after appearing to resolve

What your vet will investigate

Your vet will take a detailed history — diet, recent travel, other pets in the household, vaccination and parasite-prevention status — and perform a physical examination. A faecal smear or flotation test screens for parasites. Depending on findings, they may recommend bloodwork, faecal culture, imaging or an empirical trial of a bland diet with or without medication.

In Singapore and tropical regions, parasites are endemic year-round. The Animal & Veterinary Service (AVS) recommends keeping dogs on a regular parasite-prevention programme. If your dog has not had a faecal check in the past 12 months, a case of recurring diarrhoea is a good prompt to get one.

Medications to avoid without vet guidance

Prevention and long-term management

The most reliable prevention strategies are consistent feeding (same food, consistent timing), transitioning to any new diet over a minimum of seven days, keeping rubbish bins and food scraps out of reach, and staying current on parasite prevention. Dogs with recurrent diarrhoea may benefit from a veterinary assessment for food sensitivity, inflammatory bowel disease or exocrine pancreatic insufficiency.