My dog has been vomiting with watery diarrhoea for two days — could it be parvo or poisoning?

Most acute vomiting and diarrhoea in an otherwise healthy adult dog settles within a day or two, and the fact that he is still drinking and still himself is genuinely reassuring. But there is a short list of things that turn this into a same-hour problem, and you need to know it.

Go to your vet or your nearest emergency clinic now if he retches repeatedly without bringing anything up and his belly looks swollen or tight; if there is blood in the vomit or the stool (fresh red, or dark like coffee grounds or tar); if his gums are pale, white or grey rather than pink; if he cannot keep water down; if he collapses or won't stand; or if he might have swallowed a sock, a toy or a toxin. The same applies without hesitation if he were a puppy, a senior, or a very small dog — they run out of reserve fast.

Book an appointment today if it has passed 48 hours, if it is getting worse rather than better, or if he becomes flat and lethargic.

Meanwhile, a few things that will genuinely change the consultation. Photograph the stool. Write down each vomit with a time. Check his hydration: lift the lip and feel the gums, which should be wet and slick rather than tacky, and pinch the skin over his shoulders, which should fall straight back. Never withhold water. Bring a fresh stool sample in a sealed bag.

And please: no human medicines, and nothing off a home-remedy list. Several common ones are genuinely dangerous to dogs. Whether this is a dietary indiscretion, a parasite, parvovirus or an obstruction is decided by the exam, a faecal test and possibly imaging — not by a guess from a distance.