It’s usually about five in the morning. There’s a noise from downstairs, and by the time you’ve got there with a roll of kitchen paper you already know how the rest of the day is going.

Diarrhoea is the single most common reason dogs end up at the vet, and the great majority of cases resolve on their own within a couple of days. The difficulty is that a small minority don’t, and telling those apart at five in the morning is not straightforward.

What actually counts

A one-off soft stool isn’t diarrhoea. Dogs produce the occasional loose one for all sorts of forgettable reasons.

Diarrhoea proper means increased water content, usually with increased frequency, sustained across more than one motion. If he’s been out four times before breakfast and it’s liquid, that’s diarrhoea. If the second one of the day was softer than the first and everything else is normal, that’s a dog.

The other useful distinction, and one most owners have never heard of, is where in the gut it’s coming from.

Small intestinal diarrhoea produces large volumes, not many more times a day than usual, often with weight loss and sometimes vomiting. The dog isn’t especially urgent about it.

Large intestinal diarrhoea produces small volumes, very frequently, with obvious straining and urgency. You’ll often see mucus – a jelly-like coating – and sometimes streaks of fresh red blood. This is the one that has dogs asking to go out every twenty minutes and producing almost nothing.

That matters because large intestinal signs are frequently stress-related colitis and tend to settle quickly, whereas the small intestinal picture with weight loss is more likely to need investigating.

The first forty-eight hours

For an otherwise well adult dog, the rule of thumb is simple: give it forty-eight hours before you worry, but watch closely during them.

What helps in that window is keeping things simple and steady. Plenty of fresh water. Small, frequent, easily digested meals rather than one large one. And daily Probiotics for Dogs, which have reasonable evidence behind them for shortening acute episodes and are worth starting on day one rather than day four.

What doesn’t help is doing several things at once. Owners commonly change the food, add three supplements, give something from the human medicine cabinet and then can’t tell what worked.

The fasting question

The old advice was to starve a dog with diarrhoea for twenty-four hours. Veterinary thinking has moved on from that considerably.

The gut lining is fed partly by what passes through it, and prolonged fasting deprives it of exactly the fuel it needs to repair. Current thinking generally favours getting small amounts of appropriate food in fairly quickly.

For a healthy adult dog, skipping one meal is unlikely to hurt. Beyond that, feed small and often.

Never fast a puppy. They have almost no reserves and can become hypoglycaemic quickly. Same goes for very small breeds, very old dogs, and any dog with a known health condition.

Feeding through it

Boiled chicken and white rice is the traditional answer, and it’s fine as far as it goes. It’s bland, low fat and easy to digest.

Two things worth knowing. It isn’t nutritionally complete, so it’s a few days’ measure rather than a fortnight’s. And white rice is very low in fibre, which for large intestinal diarrhoea is arguably the wrong direction.

A veterinary gastrointestinal diet, if you can get one, is generally better – properly balanced and formulated for exactly this.

Fibre often helps more than people expect. A spoonful of plain tinned pumpkin, or psyllium husk, adds fermentable and bulking fibre that firms things up from the other direction. Plain pumpkin, incidentally, not pie filling.

Feed small portions four or five times a day rather than two normal meals.

Water is the thing that actually matters

Dehydration is what makes diarrhoea dangerous, particularly in small dogs and puppies.

Fresh water always available. If he’s not drinking, try a little unsalted bone broth or the water from boiled chicken to make it more appealing.

Two quick checks. Lift the skin over the shoulders and let go – it should spring straight back, and a slow return suggests dehydration. And press a finger against the gum; the pale spot should refill with colour in under two seconds, and the gums themselves should be moist rather than tacky.

What not to do

Don’t give human anti-diarrhoeals. Loperamide, sold as Imodium, is genuinely dangerous in some dogs. Collies, Australian shepherds, Shelties, long-haired whippets and related breeds frequently carry the MDR1 gene mutation, which prevents the drug being pumped out of the brain and can cause severe neurological effects. Even in unaffected dogs it can mask a problem or make an infection worse by slowing everything down.

Don’t reach for leftover antibiotics. Most diarrhoea isn’t bacterial, antibiotics disrupt the gut population further, and using them unnecessarily contributes to resistance.

Don’t change to a new complete food mid-episode. You’ll never know afterwards whether the food helped, hurt or did nothing, and a sudden change is itself a cause of diarrhoea.

Don’t withhold water. Ever.

The red flags

Stop waiting and ring the vet if any of these appear.

Blood in quantity, or black tarry stools – that dark colour is digested blood from higher up the gut and it’s more serious than fresh red streaks.

Repeated vomiting alongside the diarrhoea, particularly if he can’t keep water down.

Lethargy, weakness, collapse, pale or tacky gums.

A painful, tense or bloated abdomen, or a dog adopting a stretched-out praying position. That combination with unproductive retching is a genuine emergency.

Any suspicion he’s eaten something he shouldn’t have – a toy, a corn cob, a sock, chocolate, raisins, a bin bag’s worth of something.

Puppies, elderly dogs and unvaccinated dogs get a much lower threshold. Parvovirus is still around, it kills, and it starts as vomiting and diarrhoea in a young dog.

Common causes, roughly by likelihood

Dietary indiscretion. Something off the pavement, out of the bin, or off the compost heap. Far and away the most common.

A change of food made too quickly.

Stress. Kennels, house moves, fireworks, visitors. Stress colitis usually appears a day or two after the event.

Parasites. Worms, giardia. More common in puppies and dogs who drink from puddles and streams.

Infection. Viral or bacterial.

Medication, particularly antibiotics and some anti-inflammatories.

Chronic disease. Food intolerance, inflammatory bowel disease, pancreatic insufficiency, and in older dogs, occasionally something more serious. This is the group that presents as diarrhoea which keeps coming back.

Getting back to normal

Once stools are firm, go back to the usual food over about five days, mixing gradually rather than switching in one go. Rushing this is how you get a relapse on day three.

Keep the probiotic going for at least a fortnight after things settle. The population takes longer to recover than the symptoms take to disappear, which is why so many dogs have a second bout a week after the first seemed resolved.

The dog whose stools are never quite right

A different problem from acute diarrhoea, and one that gets tolerated for years because it never becomes an emergency.

This is the dog who isn’t ill, eats well, has plenty of energy, and produces a stool that starts firm and finishes soft. Or one that’s picked up in three attempts. Or that varies with nothing you can pin down.

It’s worth taking seriously rather than accepting as his normal. Persistently loose stools mean nutrients aren’t being absorbed as well as they should be, and it usually has a cause worth finding.

The usual suspects: too much food, which is more common than anyone expects and the easiest thing in the world to test; too many treats and toppers alongside a complete diet; a food that simply doesn’t suit him, often too high in fat; not enough fibre; or low-grade dysbiosis after an illness or antibiotic course months earlier.

Work through it methodically and change one thing at a time. Weigh the food rather than scooping it. Cut treats to almost nothing for a fortnight. Add fibre. Then, if nothing shifts, try a different diet properly – a full transition and four weeks on it, not a week of chopping and changing.

If none of that helps, ask your vet about faecal testing and a blood panel. Exocrine pancreatic insufficiency, chronic giardia and low-grade inflammatory bowel disease all present exactly like this, and all are considerably easier to manage once identified.

Cleaning up properly

Use an enzymatic cleaner rather than anything ammonia-based. Ammonia smells like urine to a dog and marks the spot for repeat use.

If there’s any suspicion of an infectious cause, most household disinfectants won’t touch parvovirus – that needs a specific product, and anything a sick dog has walked through wants dealing with properly before other dogs use the garden.

Stopping it happening again

If your dog gets diarrhoea several times a year, it’s worth treating that as a pattern rather than a run of bad luck.

Keep a note of each episode – date, what happened beforehand, how long it lasted. Patterns show up quickly on paper. A dog whose upsets always follow a boarding stay has a stress problem. One whose upsets follow bin day has an access problem, and a bin with a lid is the entire treatment.

Beyond that: keep the diet consistent, make changes slowly, keep worming up to date, discourage scavenging on walks, and support the gut steadily rather than only when something’s already gone wrong.

And get chronic or recurrent diarrhoea properly investigated rather than managing it indefinitely at home. Faecal testing, blood work and a dysbiosis index can identify things that no amount of chicken and rice will resolve.