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Heat Stroke in Dogs

By the Dog Health Handbook team · Updated · Fact-checked against current veterinary references (see sources)

Key takeaways

  • Heavy panting, lagging behind and reluctance to move are early warning signs.
  • Cool first, transport second: start cooling with water right away, then go to the vet.
  • Don't cover a hot dog with wet towels; they trap heat.
  • Flat-faced, overweight and giant breeds are at the highest risk.
  • Most cases follow exercise, not hot cars.

Table of Contents

Research Signs First aid What not to do At-risk dogs Outlook Prevention FAQ Sources

Dog General Diseases and Symptoms QuickLinks

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Heat stroke happens when a dog's body overheats faster than it can cool down by panting. It's an emergency. Early signs are heavy panting, lagging behind on walks and reluctance to move. Severe cases bring vomiting, wobbliness, collapse, confusion and seizures.1,2,3 The most important rule is "cool first, transport second": start cooling your dog with water right away, keep air moving, then get to a vet.4,2,5 Most cases follow exercise, not hot cars, and flat-faced, overweight and giant dogs are most at risk.6,7,1

If your dog is overheating, act now:

  1. Stop and move to shade or a cool place.1
  2. Cool with water right away, using the coldest water you have. Pour it over the whole body, away from the nose and mouth, and keep air moving with a fan or breeze.2,4,1
  3. Call your vet or an emergency clinic and keep cooling on the way, with the car's air conditioning on.1,8,2

What the Research Says

  • Exercise causes most cases. In UK vet records, about 74% of heat illness cases followed exercise, 13% hot weather alone, and about 5% being left in a vehicle.6
  • Few dogs are cooled before reaching the vet. In a 2023 study, only about 22% of dogs whose records described cooling had been cooled before reaching the vet, and wet towels, which aren't recommended, were the most common method. Dogs cooled first arrived about 4 °F (2 °C) cooler.9
  • Cold water was safe in fit dogs. In a 2024 study of dogs after canicross races, cold-water immersion cooled dogs quickly with no harm and no dangerously low temperatures.5
  • Severity matters. About 2% of dogs with mild heat illness died, compared with about 57% of severe cases.3

Signs of Heat Stroke in Dogs

StageSigns
Early or mildHeavy panting, fast or noisy breathing, tiredness, lagging behind or lying down on walks1,3,2
ModerateDrooling, vomiting or diarrhea, gum color changes, wobbliness, weakness or brief collapse1,3
SevereStumbling, confusion, seizures, unresponsiveness, bloody vomit or diarrhea, bruising on the gums or skin1,3,10

A dog's normal temperature is about 100.5 °F to 102.5 °F (38.1 °C to 39.2 °C). Above 103 °F (39.4 °C) is too hot, and heat stroke usually means about 105 °F to 106 °F (40.6 °C to 41.1 °C) or higher with signs such as collapse, confusion or seizures.8,10,11 Don't wait to take a temperature. Treat any overheated dog as an emergency.4,3

First Aid: Cool First, Transport Second

  1. Start cooling immediately, before you travel. Cooling quickly gives the best chance of a full recovery.4,1,3
  2. Young, healthy, alert dogs: put them in cold water up to the neck, keeping the head above water, if they're comfortable with it.2,1,5
  3. Older, unwell or drowsy dogs, and flat-faced breeds: pour or spray water over the body and keep air moving, rather than immersing them.2,5,9
  4. Use whatever water is closest, as long as it's cooler than your dog.2,4
  5. Keep air moving: a fan, a breeze or air conditioning.2,10
  6. If your dog is alert, offer small amounts of cool water to drink, but don't force it.1
  7. Cool the car first, then drive to the vet with the air conditioning on, and keep cooling.2,8
  8. Stop active cooling when breathing settles or your dog's temperature reaches about 103 °F, to avoid overcooling.10,11

Older advice to use only lukewarm water and cool slowly isn't well supported, and the Royal Veterinary College now recommends cooling quickly with the coldest water available.4,2 Some US sources still advise cool rather than cold water. Either way, the key is to start cooling fast.10,4

What Not to Do

  • Don't cover your dog with wet towels. They trap heat. Letting your dog lie on a cool, wet towel or surface is fine.10,1,9
  • Don't put a hot dog straight into a hot car.2,5
  • Don't use rubbing alcohol.10
  • Don't wait to see if your dog improves before cooling or calling the vet.4,1
  • Don't muzzle a hot dog, because it needs to pant.10

Which Dogs Are Most at Risk?

  • Flat-faced breeds: Bulldogs, French Bulldogs and Pugs. Flat-faced dogs had about twice the odds of heat illness in a UK study.7,12
  • Other high-risk breeds: Chow Chows, Dogues de Bordeaux, Greyhounds, Cavalier King Charles Spaniels, Springer Spaniels and Golden Retrievers.7
  • Heavier and overweight dogs, and giant breeds.7,1
  • Thick or dark coats.8,1
  • Very old and very young dogs.1,8
  • Dogs with breathing or heart problems, such as laryngeal paralysis.8

Heat illness can happen on days that don't feel very hot, especially with hard exercise.6,13

Outlook and Complications

Most dogs with early, mild heat illness recover, especially when they're cooled quickly.3,10 About 1 in 7 dogs seen by UK vets for heat illness died, and more than half of dogs with severe heat stroke did not survive.7,3 At specialist hospitals, which see the most serious cases, about half die.14,15 Older dogs, flat-faced breeds and dogs that are severely affected when they arrive have the worst outlook.13

Heat stroke can cause kidney injury, clotting problems and shock, and dogs that have had it once are more likely to have it again.8,10,15 Most deaths happen within the first day, and in one study every dog alive at 48 hours survived.11 Even if your dog seems better after cooling, a vet check is important. A dog cooled at home may have a normal temperature by the time it reaches the vet, so tell your vet what happened.10,8,16

Preventing Heat Stroke

  • Walk early or late on warm days, and skip hard exercise for high-risk dogs.1
  • Provide shade and water at all times.1,10
  • Watch for early signs and stop as soon as your dog lags or pants heavily.2,1
  • Keep your dog at a healthy weight. Obesity raises the risk of heat stroke and makes the outlook worse.1,7,16
  • Build up slowly when hot weather arrives or after moving somewhere warmer. Dogs take at least 10 to 20 days to adjust to heat.16
  • Check the pavement: if you can't hold your palm on it for 7 seconds, it's too hot.1
  • Never leave your dog in a car on a warm day, even briefly, with windows open or in shade.1,8 On a 73 °F day, the inside of a car can reach 100 °F in about 25 minutes, and cracked windows barely slow it.17

See also dog panting and dehydration in dogs.

Frequently Asked Questions

What are the first signs of heat stroke in dogs?

Heavy panting, lagging behind or lying down on walks, and reluctance to move.

What should I do if my dog has heat stroke?

Cool first, transport second: pour the coldest water you have over your dog (or immerse a young, healthy, alert dog), keep air moving, then go to the vet.

Can I use cold water to cool my dog?

Yes. Recent research supports cold water for young, healthy dogs. Pour water rather than immersing older, sick or drowsy dogs.

How long does heat stroke last in dogs?

Mild cases often improve quickly with cooling, but complications can appear over the next day, so see a vet.

Can dogs survive heat stroke?

Most dogs with mild heat illness survive. More than half of severe cases die, so fast cooling matters.

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Sources and further reading

This article was rewritten and fact-checked on October 28, 2026 against current veterinary references and specialist guidelines:

  1. PDSA vets and vet nurses. Heatstroke in Dogs. PDSA Pet Health Hub, September 2023.
  2. Royal Veterinary College VetCompass. How to Cool Hot Dogs. RVC, undated.
  3. Hall EJ, Carter AJ, Bradbury J, Barfield D, O'Neill DG. Proposing the VetCompass clinical grading tool for heat-related illness in dogs. Scientific Reports, 2021.
  4. Royal Veterinary College. The RVC urges owners of hot dogs to "cool first, transport second". RVC VetCompass news, July 2023.
  5. Carter AJ, Hall EJ, Bradbury J, Beard S, Gilbert S, Barfield D, O'Neill DG. Post-exercise management of exertional hyperthermia in dogs participating in dog sport (canicross) events in the UK. Journal of Thermal Biology, 2024.
  6. Hall EJ, Carter AJ, O'Neill DG. Dogs don't die just in hot cars: exertional heat-related illness (heatstroke) is a greater threat to UK dogs. Animals, 2020.
  7. Hall EJ, Carter AJ, O'Neill DG. Incidence and risk factors for heat-related illness (heatstroke) in UK dogs under primary veterinary care in 2016. Scientific Reports, 2020.
  8. Cornell Richard P. Riney Canine Health Center (bio shown: Aly Cohen, DVM). Heatstroke: A medical emergency. Cornell University College of Veterinary Medicine, date not shown.
  9. Hall EJ, et al. Cooling methods used to manage heat-related illness in dogs presented to primary care veterinary practices during 2016-2018 in the UK. Veterinary Sciences, 2023.
  10. Weir M, DVM, MSc, MPH; Williams K, BSc, DVM, CCRP; Ward E, DVM. Heat Stroke in Dogs. VCA Animal Hospitals, last updated July 10, 2025.
  11. Johnson SI, McMichael M, White G. Heatstroke in small animal medicine: a clinical practice review. Journal of Veterinary Emergency and Critical Care, 2006.
  12. Ewers Clark A. Heatstroke and brachycephalic dogs: is there an increased risk? Veterinary Evidence, 2022.
  13. Hall EJ, et al. Risk factors for severe and fatal heat-related illness in UK dogs: a VetCompass study. Veterinary Sciences, 2022.
  14. Bruchim Y, Klement E, Saragusty J, et al. Heat stroke in dogs: a retrospective study of 54 cases (1999-2004) and analysis of risk factors for death. J Vet Intern Med. 2006;20(1):38-46.
  15. Bruchim Y, Horowitz M, Aroch I. Pathophysiology of heatstroke in dogs: revisited. Temperature, 2017.
  16. Serrano S. Heat Stroke and Hypothermia. LAVC Latin American Veterinary Conference, Lima (IVIS), 2012.
  17. National Weather Service. Heat Safety: Vehicles. US Department of Commerce, accessed October 2026 (citing McLaren C, et al., Pediatrics 2005).

About this article

Last updated : written using VetCompass studies from the Royal Veterinary College, Cornell University, VCA, PDSA, Veterinary Evidence, the National Weather Service and studies published 2006 to 2024.

This page is for general information and is not a substitute for an exam by your veterinarian.