Heatstroke in Dogs: Signs, First Aid and When to See a Vet

If your dog pants hard and won’t settle, turns wobbly or collapses in the heat or after exercise, cool it with water straight away, then take it to a vet. Vets call this “cool first, transport second”. This guide follows UK vet-record research from the Royal Veterinary College (RVC), the 2026 RECOVER first aid guidelines for vets, and advice from the RSPCA, PDSA, Dogs Trust, the British Veterinary Association (BVA), the American Veterinary Medical Association (AVMA) and VCA hospitals, all checked on 22 October 2026.

Why dogs overheat

Dogs cool themselves mainly by panting: they only have sweat glands on their paws (Cornell), and panting works less well when the air is humid (Dogs Trust). A dog’s normal rectal temperature is 37.5 to 39.2°C (99.5 to 102.5°F) (Merck Veterinary Manual). Strictly, heatstroke is the most serious stage of heat-related illness: a temperature above 41°C (105.8°F) with signs that the brain is affected (RECOVER, 2026).

In UK vet records from 2016, about 1 in 7 dogs treated for heat-related illness died (Hall et al., 2020). Catching it early matters: 98% of dogs taken to the vet with early signs survived, while 57% of those with severe signs died (RVC).

Signs of heatstroke in dogs

The two commonest signs in UK vet records were changes in breathing (69% of cases) and tiredness (48%) (Hall et al., 2021).

Early signs: stop, cool your dog, call your vet

• Heavy panting that carries on after your dog has stopped and rested (Dogs Trust)
• Breathing that is faster or noisier than usual, especially in a flat-faced dog (RSPCA)
• Thick, sticky drool (RSPCA)
• Bright red gums and tongue (RSPCA, Dogs Trust)
• Restless and seeking shade, or the opposite: tired, stiff, lying down mid-walk (Dogs Trust, RECOVER)

Signs to see a vet now. Go now if your dog:

• Vomits or has diarrhoea, especially with blood (PDSA)
• Is wobbly, stumbles or collapses, even for a moment (Dogs Trust, PDSA)
• Has a seizure, seems confused or doesn’t respond to you normally (PDSA, BVA)
• Has very pale or blue gums, or bruises on the gums or skin (PDSA, BVA, VCA)

Look at your dog’s gums on a normal day, so you know what a change looks like.

First aid: cool first, then go to the vet

Start cooling where you are, before you travel: any delay in cooling makes the outcome worse (Hall et al., 2023).

1. Get out of the heat. Stop the walk or game and move your dog into shade, a cool room or air conditioning (RECOVER).
2. Cool with water. For a young, healthy dog, use cold water: put the dog in a tub, paddling pool or stream, or under a running tap or hose, keeping its head out of the water (Dogs Trust, RSPCA). For an older dog or one with other health problems, pour or spray water over the body and point a fan at it; Dogs Trust and the RSPCA suggest room-temperature water for these dogs. This split comes from US emergency vets’ 2016 guidance (Hall et al., 2023). Keep water away from the nose and mouth (PDSA), and never put an unconscious dog in water (RSPCA).
3. Don’t just drape wet towels over your dog. It was the commonest cooling method in UK vet records, used on about half the dogs whose cooling was recorded, but it isn’t a recommended one (Hall et al., 2023). A towel laid over the dog can trap heat; a wet towel underneath is fine (RSPCA).
4. Cool for about 15 minutes before you set off, the time the 2026 RECOVER first aid guidelines for vets suggest when you can’t take your dog’s temperature. Stop sooner if your dog recovers (its breathing settles and it responds normally) or starts to shiver (VCA, Dogs Trust): a dog can be cooled too far. With a thermometer, stop at about 39.4 to 40°C (103 to 104°F): VCA stops at 39.4°C, RECOVER at 39.7 to 40°C.
5. Offer small sips of water if your dog is alert, but don’t force it (RVC).
6. Go to the vet, even if your dog seems fine. Phone ahead and travel with the air conditioning on or the windows open (RSPCA). Serious effects, such as kidney injury, may not show straight away (RVC, Cornell).

Older advice said to use only cool or lukewarm water. The BVA now says cold water brings a dog’s temperature down faster without adding risk (BVA). Use whatever water you have, as long as it’s cooler than your dog (Dogs Trust).

Where vets’ advice differs. VCA says cool, not cold, water, and calls ice packs no longer recommended, while PDSA and Dogs Trust suggest ice wrapped in a tea towel in the groin or armpits, alongside water. The 2026 RECOVER guidelines suggest cool running water over the belly, where the fur is thinnest, and for a dog with noisy breathing, cooling until its panting clearly eases or it reaches 38.6°C (101.5°F). They add that neither the best method nor the right stopping point has been studied in dogs. All agree on the main thing: start cooling quickly, then see a vet.

Which dogs are most at risk

Any dog can get heatstroke. In UK vet records (Hall et al., 2020):

• Flat-faced (brachycephalic) dogs had about twice the odds of dogs with medium-length noses. Bulldogs had about 14 times the odds of Labradors, French Bulldogs about 6.5 times and Pugs about 3 times. A short muzzle makes panting less effective (RSPCA); see pug breathing problems and heatstroke.
• Heavy dogs. Dogs over 50 kg had 3.4 times the odds of dogs under 10 kg, and dogs at or above the average weight for their breed and sex had higher odds. Obesity has also been linked to dying from heatstroke (RECOVER). The rib and waist check in the Labrador weight guide works for any breed.
• Older dogs. Dogs aged 12 or more had the highest odds of any age group, and over three times the odds of young dogs of overheating just from being outdoors on a hot day (Hall, Carter and O’Neill, 2020).
• Thick coats. Golden Retrievers had about 2.7 times the odds of Labradors, possibly because of the thicker coat, the researchers suggest. In India, for example, see Golden Retrievers and the heat.

Puppies, dogs with heart or breathing problems and dogs not used to warm weather are at higher risk too (Dogs Trust). VCA adds that a muzzle can make it harder to pant.

Exercise is the commonest trigger

Hot cars get the attention, but in UK vet records exercise caused 74% of heat-related illness with a known cause; where the activity was recorded, two-thirds of those cases followed a walk. Hot cars caused 5%. Exercise affected about ten times as many dogs as hot cars and caused eight times as many deaths, and younger dogs and male dogs were most at risk of it (Hall, Carter and O’Neill, 2020).

It doesn’t have to feel hot to you. Dogs Trust cites a study in which a significant number of dogs were diagnosed with heatstroke when it was only 16.9°C, and RECOVER notes that cases often rise on the first warm days of spring, before dogs are used to the heat.

Hot cars

Never leave a dog in a parked car. The AVMA says the inside of a car can warm by about 20°F (11°C) in 10 minutes and by more than 40°F (22°C) in an hour, even in the shade, and that cracking the windows makes no difference (AVMA). On a 22°C day, says the RSPCA, a car can reach 47°C within an hour (RSPCA).

If you see a dog in distress in a hot car: in England and Wales, the RSPCA says dial 999 if the dog shows signs of heatstroke; Dogs Trust gives 999 for the rest of the UK, and 112 or 999 for the Gardaí in Ireland. Elsewhere, save your local police or animal control number before you need it.

Hot pavements

Hot asphalt can burn a dog’s paws (AVMA). Dogs Trust suggests holding your hand on the pavement for five seconds: if it’s too hot for you, walk later. PDSA’s vets use seven seconds with your palm, and note that sand, artificial grass and tarmac get especially hot. Walk on grass where you can (RSPCA).

Preventing heatstroke in hot weather

• Walk in the coolest hours, early morning or late evening, and skip very hot days (AVMA). PDSA advises no exercise on hot days for dogs that are unfit, elderly, young, overweight, unwell or have breathing problems.
• Carry water and offer small amounts every 15 to 20 minutes (RSPCA).
• Watch your dog, not the clock. Some dogs keep playing when they’re already hot and tired (Dogs Trust).
• Give shade, water and cooler spots at home (AVMA), and keep dogs out of conservatories and hot rooms (RVC).
• Use a harness, not a collar, so nothing presses on the throat (PDSA).
• Keep your dog at a healthy weight (PDSA).
• Ask your vet about coat care, such as a warm-weather haircut (AVMA). PDSA says brushing helps too.

After heatstroke

Your vet may give fluids, oxygen and medicines, and severe cases can need several days in hospital. Once home, watch your dog closely for 24 to 48 hours and call the vet if it vomits, has diarrhoea, seems confused or eats less (PDSA). A dog that has had heatstroke is more likely to get it again (VCA, Cornell), so take extra care in the next hot spell.

FAQs

What colour are a dog’s gums with heatstroke? Often bright red at first (RSPCA, RVC). Very pale or blue gums, or bruises on the gums, are signs to see a vet now (PDSA, BVA, VCA): cool your dog and go.

Can dogs get heatstroke in winter? Yes. In UK records, exercise-triggered cases happened in every month (Hall, Carter and O’Neill, 2020), and Dogs Trust says dogs can overheat at any temperature.

How hot is too hot to walk my dog? There’s no single number: it depends on your dog’s breed, age and health (Dogs Trust). Walk in the coolest hours, test the pavement, and stop at the first sign of heavy panting.