In this article
  1. Heatstroke starts on walks more often than in cars
  2. Which dogs are most at risk
  3. The early signs
  4. Cool first, transport second: what to do
  5. Is cold water dangerous?
  6. Why a wet towel over your dog can backfire
  7. After the emergency, and next summer

It is a warm afternoon rather than a scorching one, and the walk home is taking longer than it should. Your dog keeps stopping, still panting hard after a rest in the shade. The natural thing is to bundle them into the car and head for the vet. Vets and UK charities now say to do something else first.

That something is cooling. "Cool first, transport second" is how Dogs Trust and the RSPCA put it1, 2, and the 2026 RECOVER first aid guidelines, written by an international panel of veterinary experts, recommend cooling a dog with heatstroke before it travels3. Here is who is most at risk, what to look for, and how to cool your dog safely, cold water included.

Heatstroke starts on walks more often than in cars

The summer warning about hot cars still stands: a dog left in one could die within minutes, and winding a window down is not enough1. But when researchers went through the veterinary records of 905,543 dogs seen by UK vets in 2016, most heat illness had another cause4.

Of the cases where a trigger was recorded, 74.2% followed exercise, 12.9% came from being somewhere hot, and 5.2% from a hot vehicle4. Where the activity was noted, 67.5% of the exercise cases followed a walk4. Exercise affected around ten times as many dogs as hot cars did, and caused eight times as many deaths4.

Heat illness in UK dogs

  • 74.2%of cases with a known cause were set off by exercise4
  • 67.5%of those, where the activity was recorded, followed a walk4
  • 1 in 5dogs whose vet records mention cooling had been cooled before they arrived5

Nor is it only a heatwave problem. Exercise cases turned up in every month of the year4. A 2022 study used a heat-stress index that combines air temperature, sunshine, humidity and wind: on the typical day a dog fell ill, it peaked at 16.9 °C. The authors suggest UK dogs develop heat illness at relatively low temperatures compared with dogs in Israel, where they can acclimatise to heat7.

Which dogs are most at risk

Any dog can overheat, but some breeds turn up far more often. In the 2016 records, nine breeds had higher odds of heat illness than Labrador Retrievers once age and weight for their breed were allowed for6. These are the top seven.

Odds of heat illness compared with a Labrador
BreedOdds compared with a Labrador
Chow Chow16.61 times6
Bulldog13.95 times6
French Bulldog6.49 times6
Dogue de Bordeaux5.31 times6
Greyhound4.26 times6
Cavalier King Charles Spaniel3.45 times6
Pug3.24 times6

English Springer Spaniels and Golden Retrievers made the list too6. The Chow Chow figure rests on a small number of dogs, so its margin of error is very wide6. Flat-faced dogs had 2.10 times the odds of dogs with a medium-length muzzle, and dogs heavier than average for their breed, dogs over two and dogs over 50 kg were also at greater risk6.

Age matters too. Young male dogs were more likely to overheat through exercise, and dogs aged 12 or over had more than three times the odds of dogs under two of falling ill from being somewhere hot4. Once ill, older and flat-faced dogs were more likely to die7.

The early signs

Heat illness tends to build in stages, from tiredness and changed breathing, through vomiting or a brief collapse, to a severe stage with bleeding problems and liver and kidney damage7. The longer a dog stays overheated, the more harm it does2, so the early signs Dogs Trust lists are worth learning1.

Signs your dog is overheating

  • Heavy panting that carries on after they have stopped
  • Changes to their breathing, or struggling to breathe
  • Bright pink or red gums
  • Seeming tired, drowsy, stiff or unwilling to move
  • Wobbly or uncoordinated walking
  • Drooling more than usual, vomiting or diarrhoea
  • Collapse or a seizure

The commonest are changes to breathing and tiredness or drowsiness, according to Dogs Trust, which also warns that some dogs keep running and playing even when they are hot and tired1. End the game before your dog would.

Cool first, transport second: what to do

Driving off first costs time, and UK researchers say any delay to cooling worsens the outcome5. So the order is cool, then go.

Cool first, transport second

  1. StopEnd the walk or game at once1
  2. Get out of the heatInto shade or a cool room, away from the sun and out of any hot car2, 8
  3. Soak themPour or run cool water over the body, especially the belly and thighs, keeping it off the head3, 2
  4. Make a breezeFan them, or use a fan or air conditioning if you have one1, 2
  5. Call your vetFor advice, including when to stop cooling and set off, and so the practice is ready for you1, 2
  6. Then goTravel with the air conditioning on or the windows open, with someone to keep cooling if possible1, 8

Keep the water flowing. RECOVER suggests cool running water on the trunk, especially the thin-haired belly, soaking right down to the skin3. Running water is thought to work better than a single dousing, it explains, because still water can form an insulating layer, and the panel does not recommend cooling only the paws3.

Offer a drink, but don't force it8. Stop cooling if your dog starts to shiver1, and don't put yourself in danger to do any of this3. Even if your dog perks up, go to the vet straight after cooling3, 2.

Is cold water dangerous?

It is a fair question, with a history. Older veterinary texts and first aid advice often said to use only tepid water, an idea that may trace back to a laboratory study in which some dogs died when put into ice-cold water5. A team led from the Royal Veterinary College notes anecdotal reports of cooling being delayed because the water to hand was thought too cold5.

They add that the worry that cold water could make a hot dog hotter, through shivering and narrowed blood vessels in the skin, has persisted despite extensive evidence to the contrary, though most cooling research has been done in people5. UK charities now say to use any water cooler than your dog1, 2, and PDSA says water from the cold tap is fine8.

Contrary to popular belief, cold water rarely causes shock in over-heating dogs2.

Lauren Bennett, dog welfare expert at the RSPCA

Where the advice differs: putting your dog in water

Dogs Trust and the RSPCA say a young, conscious, healthy dog can go into a paddling pool or stream of cool water, head kept above the surface1, 2. Not an unconscious dog, an elderly one or one with health problems: spray those with room-temperature water and add a breeze1, 2.

The RECOVER panel chose not to suggest a tub or sink, judging the risk of a pet drowning, and to the person helping, too high3. Everyone agrees on the part that matters most: plenty of cool water over the body, straight away3, 1, 2.

How strong is the evidence?

How sure can anyone be? RECOVER found no studies directly comparing cooling before transport with no cooling in dogs3. In one study of 42 dogs, 13 of the 27 survivors had been cooled by their owners first, against 3 of the 15 that died or were put to sleep, a difference that could have been chance3. The panel rated the evidence as very low quality but still made a strong recommendation, because what evidence there is points one way and a lack of fast cooling has dramatic consequences3.

Why a wet towel over your dog can backfire

In UK vet records from 2016 to 2018, only 74 of the 341 dogs whose records mentioned cooling, about one in five, had been cooled before they arrived5. Wet towels were the method written down most often, for about half of the 267 dogs whose method was recorded, mostly at the practice5. Only 23.97% of those 267 got cold-water immersion or a water spray with moving air, the two methods vet guidelines recommended in 20165.

The study could not say which method works best5. But dogs cooled beforehand arrived cooler on average, and only eight of those 74 were given more cooling at the practice5.

Towels have not been properly tested in dogs. In people, wet towels cool more slowly than cold-water immersion, and in horses they were found not to work5. Covering a dog, even with a wet towel, can stop air moving around it and trap heat5, 2. A cold, wet towel underneath is fine, if you re-wet it often2, 8.

Cooling a hot dog

Do

  • Pour or run cool water over the body, especially the belly3
  • Use whatever water you have, as long as it is cooler than your dog1
  • Let them lie on a cold, wet towel, re-wetting it often2, 8

Don’t

  • Drape a wet towel over their back1, 2
  • Pour water over their head or near the nose and mouth2, 8
  • Wait to find tepid water, or hold them close for a cuddle5, 8

After the emergency, and next summer

Illustration: a vet listening to a dog's chest with a stethoscope on an examination table

Most dogs pull through. In the 2016 records, about one heat illness event in seven ended in death6, and PDSA says a mild case cooled and treated quickly is likely to make a full recovery8. Once your dog is home, watch them closely for a day or two, and tell your vet about any vomiting, diarrhoea, confusion or loss of appetite8.

Dogs with breathing problems, heart disease or a flat face are at greater risk in the heat1. If yours is one of them, ask your vet what a safe summer looks like for them.

Before a warm-weather walk

  • Go out early in the morning or late in the evening1
  • Hold your hand on the pavement for five seconds: if it is too hot for you, walk later1
  • Take water with you8
  • Clip the lead to a harness, which takes pressure off the throat and makes panting easier, especially for flat-faced dogs8
  • Skip exercise on hot days if your dog is unfit, elderly, young, overweight, unwell or has breathing problems8
  • Never leave your dog in the car, even with a window down1

Heatstroke does not need a heatwave, just a warm day and a dog who would rather keep going. Know the signs, keep water to hand, and if your dog does overheat, remember the order: cool first, then go.

Sources and further reading8 sources

The small numbers in the article link to the source behind each fact. Sources open on their own websites.

  1. Caring for your dog during hot weatherDogs Trust
  2. Heatstroke in dogsRSPCA
  3. RECOVER Guidelines: First Aid in Dogs and Cats. Evidence and Knowledge Gap Analysis With Treatment RecommendationsJournal of Veterinary Emergency and Critical Care (Wiley)
  4. Dogs Don’t Die Just in Hot Cars—Exertional Heat-Related Illness (Heatstroke) Is a Greater Threat to UK DogsAnimals (MDPI)
  5. Cooling Methods Used to Manage Heat-Related Illness in Dogs Presented to Primary Care Veterinary Practices during 2016–2018 in the UKVeterinary Sciences (MDPI)
  6. Incidence and risk factors for heat-related illness (heatstroke) in UK dogs under primary veterinary care in 2016Scientific Reports
  7. Risk Factors for Severe and Fatal Heat-Related Illness in UK Dogs—A VetCompass StudyVeterinary Sciences (MDPI)
  8. Heatstroke in dogsPDSA