Signs of heatstroke in dogs, and what to do

Quick answer

Heatstroke in dogs escalates faster than most owners expect, and the early signs read like ordinary enthusiasm. Watch for panting that gets heavier rather than settling once the dog is in shade, a dog that slows or lags, thick drool, and very red gums. If you see those: stop, get into shade, offer water, wet the coat with cool — never ice-cold — water, and call a vet. Do not finish the route because you are nearly home. This is an emergency that responds well to early action and badly to being waited out.

Why the early signs matter more than the dramatic ones

By the time a dog is staggering or collapsing, a great deal has already happened. The signs worth training yourself to notice are the unremarkable ones, because that is the window where stopping the walk is enough.

Panting that does not settle. Every dog pants in warm weather. The signal is direction: a dog that reaches shade and gradually settles is coping; a dog whose panting gets faster and harder in shade is not.

Slowing, lagging, or wanting to lie down. Particularly in a dog that normally pulls. A dog that stops being interested in the walk is telling you something.

Drool that changes. Thicker, ropier or much more copious than usual.

Gum colour. Very red gums are a common early sign; pale or bluish gums are a late and serious one.

Unsteadiness, confusion, vomiting or diarrhoea. These are not early signs. If they are present, this is already an emergency.

VCA Animal Hospitals describes fast breathing, abnormal gums, lethargy and disorientation among heatstroke signs, and A body temperature above 39.4°C is abnormal for a dog, according to VCA. A thermometer reading is useful if you happen to have one — but do not delay getting the dog cool, or delay a phone call, in order to find one.

What to do, in order

Stop. Not at the corner, not at home. Now.

Get out of the sun. Shade, indoors, a shop doorway — whatever is closest.

Cool the dog with cool water, not ice-cold. Wet the coat, especially the belly, armpits, groin and paws, where blood vessels run close to the surface. Very cold water is counterproductive: it constricts surface vessels and slows heat loss from the core, and it can trigger shivering, which generates heat.

Move air over the wet coat. Evaporation is what actually removes heat. A breeze, a fan, a car with the windows down, someone waving a jacket — all of it helps more than more water does.

Offer water to drink, but do not force it. A dog that wants to drink should be allowed to. A dog that is not fully alert should not be made to.

Call a vet. While you are cooling, not after. Say that you suspect heatstroke so they can prepare.

What makes it worse

Ice baths and ice packs. See above — cool, not cold.

Wrapping the dog in a wet towel and leaving it there. A warm wet towel becomes insulation. Re-wet it, and keep the air moving.

Carrying on because you are nearly home. The remaining distance is the problem, not the solution.

Waiting to see if it passes. It is the one strategy with no upside.

Leaving a dog in a car with the windows cracked. A parked car is a separate and much faster version of this whole article.

Who is most at risk

Some dogs reach trouble earlier than others, and it is worth knowing which category yours is in before a hot afternoon rather than during one.

In a Royal Veterinary College study of more than 900,000 UK dogs, flat-faced breeds had about twice the odds of heat-related illness. Beyond breed: overweight dogs, thick-coated dogs, very young and older dogs, and dogs with heart or airway conditions all have less margin. So does any dog that has had a heat episode before.

Exertion is the multiplier across all of them. Most heat-related illness in dogs is associated with exercise rather than with simply being somewhere warm — which is the encouraging part, because exertion is the variable you control. A short, flat, shaded amble is a genuinely different proposition from a game of fetch in the same weather.

How serious is it, honestly

Serious enough to act on immediately, and not a reason to panic about every warm day.

The outcome data that exists is sobering: in that same Royal Veterinary College work, 1 in 7 dogs treated for it died. Read that precisely — it describes dogs already taken to a vet for heat-related illness, which is a selected group, and it is a UK primary-care population rather than a statement about dogs anywhere. It is not a prediction about your dog. What it does establish is that this is a condition where getting to a vet early genuinely matters.

The practical takeaway is not fear. It is that the cheap intervention — stopping the walk at the first sign, in the shade, with cool water — is enormously more effective than the expensive one.

Sources

• VCA Animal Hospitals (Ward E, Panning A) — Heat Stroke in Dogs: https://vcahospitals.com/know-your-pet/heat-stroke-in-dogs
• Hall EJ, Carter AJ, O'Neill DG — Incidence and risk factors for heat-related illness (heatstroke) in UK dogs under primary veterinary care, Scientific Reports (Royal Veterinary College, VetCompass): https://pmc.ncbi.nlm.nih.gov/articles/PMC7303136/
• PDSA — Heatstroke in dogs: https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/heatstroke-in-dogs

This is not veterinary advice. It is a summary of what published veterinary sources say, written for PawPrint, written to help you decide whether to call one. If you are worried about your dog right now, call a vet rather than reading further.