Heatstroke is a life-threatening emergency. The signs are heavy, frantic panting, drooling, bright red gums, weakness, vomiting, staggering and collapse. Cool the animal immediately with cool — not icy — water and take it to a vet straight away, even if it seems to recover. Never leave a dog in a parked car: the temperature inside can become lethal within minutes.
Key facts:
- Warning signs: heavy panting, drooling, bright red gums, weakness, vomiting, staggering, collapse.
- First aid: move to shade, cool with cool (never icy) water, offer small sips, go to the vet.
- Go to the vet even if it seems to recover — internal damage can appear hours later.
- Never leave a dog alone in a parked car, not even for a few minutes.
- Highest risk: flat-faced (brachycephalic) breeds, overweight pets, senior animals and puppies.
Dogs do not sweat. They cool themselves almost entirely by panting, and when panting cannot keep up, their body temperature climbs — fast. Heatstroke kills healthy dogs every summer, and most of those deaths were preventable.
What are the signs of heatstroke?
Early on: heavy, frantic panting, restlessness, drooling and bright red gums and tongue. As it progresses: weakness, vomiting or diarrhoea (sometimes with blood), staggering and disorientation, and finally collapse, seizures and loss of consciousness. If you are asking yourself whether it is heatstroke, treat it as heatstroke.
What do I do immediately?
Get it out of the heat, into shade or air conditioning. Cool it with cool water — pour or spray it over the body, concentrating on the belly, the groin, the armpits and the paws, where the blood vessels are closest to the surface. A breeze or a fan over the wet coat speeds this up considerably.
Do not use ice or iced water. It sounds counter-intuitive, but extreme cold makes the surface blood vessels constrict, which traps the heat inside and can send the animal into shock. Cool, not freezing.
Offer small sips of water if the dog is conscious and able to drink — never force water into an animal that is collapsed. And then go to the vet, cooling it on the way.
Why go to the vet if it seems better?
Because heatstroke damages more than the temperature suggests. Even after the animal has cooled and looks recovered, it can develop kidney failure, clotting disorders, brain swelling and organ damage in the following hours. A dog that walks out of the garden looking fine can deteriorate that night. Every case needs veterinary assessment.
Which dogs are most at risk?
Flat-faced (brachycephalic) breeds — Bulldogs, Pugs, Boxers, Shih Tzus — are at the top of the list, because their compressed airways mean they move far less air when they pant, so their cooling system barely works. Also at high risk: overweight pets, senior animals, puppies, dogs with heart or respiratory disease, and thick-coated breeds. We cover this in more depth in our guide to brachycephalic syndrome.
How do I prevent it?
Never leave a dog in a parked car — not with the windows cracked, not in the shade, not “just for five minutes”. The interior can reach lethal temperatures within minutes. Walk in the early morning and late evening, not in the middle of the day, and check the pavement with the back of your hand: if it is too hot for your skin, it is too hot for paws. Always provide shade and fresh water, and never exercise a dog hard in the heat, however keen it seems — many dogs will run themselves into heatstroke rather than stop.
Frequently asked questions
What are the first signs of heatstroke?
Heavy, frantic panting, drooling and bright red gums, followed by weakness, vomiting and staggering.
Should I use ice water to cool my dog?
No. Use cool water. Iced water constricts the surface vessels, traps heat inside and can cause shock.
My dog seems fine now — do I still need the vet?
Yes. Organ damage from heatstroke can appear hours later. Every case must be assessed.
Can I leave my dog in the car with the window open?
No. The car heats up regardless and can become lethal within minutes.
Heatstroke means emergency care, hospitalisation and intensive monitoring. Petplan España (Petplan Ibérica, S.L.) reimburses 100% of the vet bill up to €3,100 a year, with a €45 excess, at any vet you choose. See the policy terms.
