Dog Heatstroke Prevention: What 167,000 Cases Want You to Know

You've heard the warnings. Don't leave your dog in the car. Don't walk them at midday. Keep them out of direct sun. You're probably doing all of that.

And yet, according to new peer-reviewed research from the Royal Veterinary College, 1 in 4 dogs that develops emergency heatstroke doesn't make it.

The data is in. And some of it will surprise you.

In 2024, researchers at the RVC's VetCompass programme published the most detailed emergency-care heatstroke study ever conducted on dogs - analysing clinical records from 167,751 dogs treated at Vets Now emergency clinics across the UK in 2022. The findings don't just tell us which dogs are most at risk. They challenge almost everything the average dog owner believes about when, why, and how heatstroke happens.

A quick note for US readers: yes, this research comes from the UK. And yes, you might be tempted to think "British summers are mild — this doesn't apply to me." That instinct is exactly backwards. These cases were recorded in a country where summer temperatures rarely break 90°F. If your dog is in Florida, Texas, Arizona, or anywhere the thermometer regularly hits triple digits, the risk isn't lower than what this study found. It's significantly higher. The UK data is the floor, not the ceiling.

This is what the science actually says - and what to do about it.

The Numbers Every Dog Owner Should Know

The study identified 384 confirmed heatstroke cases from 167,751 emergency presentations. That's 0.23% of all emergency cases. Small percentage. But here's what that number is hiding:

The event fatality rate was 26.56%. More than one in four dogs that arrived at an emergency clinic with heatstroke did not survive.

Compare that to the 2016 VetCompass study of 905,543 dogs under primary (non-emergency) veterinary care, which found a fatality rate of 14.18% for heat-related illness. When dogs end up in emergency care for heatstroke, the survival odds drop dramatically.

And this: 59.6% of all 2022 heatstroke cases occurred in just 40 days — the five heatwave periods of that year. When temperatures spike, the risk to your dog spikes with them. That's not a reason to relax on mild days. It's a reason to have your prevention routine locked in before the heat arrives.

Which Dog Breeds Are Most at Risk for Heatstroke

Not all dogs face the same risk. The research is unambiguous about this - and some of the results will make you rethink your assumptions.

Flat-Faced Breeds: The Highest-Risk Group

Brachycephalic dogs - the flat-faced, short-skulled breeds - are in a category of their own when it comes to heatstroke risk.

The 2024 Beard et al. study found that French Bulldogs and English Bulldogs alone made up 36.98% of all emergency heatstroke cases. A third of all emergency heatstroke presentations. From two breeds.

Across all brachycephalic breeds, the data shows they are 4.21 times more likely to develop heatstroke than dogs with a natural skull length (think Labrador, Border Collie, German Shepherd).

When the researchers drilled down by breed, the numbers got starker:

• Newfoundland dogs: 15x more likely to suffer heatstroke than a Labrador Retriever

• Chow Chows: 17x more likely than a Labrador Retriever

The reason flat-faced breeds are so vulnerable comes down to airflow. Dogs cool themselves primarily by panting — moving air rapidly over nasal passages to create evaporative heat loss. Brachycephalic dogs have compressed airways, narrowed nostrils, and elongated soft palates. They have to work significantly harder to move the same volume of air, which means their cooling system is already running at a deficit before the heat even starts.

If you have a French Bulldog, Pug, English Bulldog, or similar breed: the risk is not theoretical. The emergency rooms are seeing it in real time. (We wrote a whole guide on French Bulldog overheating  - it's worth reading alongside this one.)

The Surprise Entry: Golden Retrievers and Double-Coat Breeds

Here's the one that tends to shock people.

Golden Retrievers, Labrador Retrievers, Huskies, and other thick or double-coated breeds appear repeatedly across VetCompass heatstroke research. In the 2016 VetCompass primary care study (O'Neill et al., Scientific Reports), Golden Retrievers were identified as one of nine breeds with significantly elevated odds of heat-related illness compared to crossbred dogs.

The mechanism is different from brachycephalic breeds but equally serious. A double coat — designed to insulate in cold weather — traps hot air against the body when temperatures rise. Rather than releasing heat, the coat retains it, turning the dog's own fur into a passive heat trap.

The science is clear on this: a dog with a thick double coat and a flat-faced dog are at elevated risk for completely different reasons. One can't breathe efficiently. One can't release heat efficiently. Both are in danger on a warm day.

This is why you'll see Chow Chows, Golden Retrievers, and Bernese Mountain Dogs sitting down mid-walk and refusing to move before they show any obvious signs of distress. Their bodies are telling them something is wrong before their panting makes it visible to you.

Size and Age: The Risk Multipliers

Two more factors that the research consistently flags:

Weight: Giant breed dogs weighing over 50kg are three times more likely to develop heatstroke. More body mass generates more heat, and large dogs have a higher surface-area-to-volume ratio problem — they produce more heat than they can efficiently radiate.

Age: Dogs over 12 years are the most at-risk elderly cohort. Cardiovascular efficiency declines with age, and older dogs have a reduced ability to regulate core body temperature. They also tend to have underlying conditions (heart disease, arthritis, obesity) that compound the risk.

Overweight dogs of any breed are at significantly elevated risk. Excess body fat acts as insulation, retaining heat and placing additional strain on the heart during cooling attempts.

The Trigger That's Actually Killing Dogs 

(It's Not Hot Cars)

This is the finding that changes everything.

Ask most dog owners what causes heatstroke, and they'll say hot cars. The "dog left in a car" story is the one that goes viral. It's the one public awareness campaigns are built around. And yes — leaving a dog in a hot car is dangerous and inexcusable.

But according to the data, it is not the primary cause of dog heatstroke.

In the 2024 Beard et al. emergency study, exercise triggered 51.46% of all heatstroke cases. Hot environments (outdoors) accounted for 31.02%. Hot vehicles? Just 12.41%.

The 2020 VetCompass study ("Dogs Don't Die Just in Hot Cars," Animals journal) looked at 1,222 dogs from a pool of 905,543 and found exercise responsible for 74.2% of all heat-related illness events. Vehicular confinement accounted for just 5.2%.

Read that again: exercise is more dangerous than hot cars. By a significant margin. Across multiple independent studies.

And critically - the same study found that exercise-induced heatstroke was just as likely to kill a dog as heatstroke caused by vehicular confinement. The trigger differs. The fatality risk does not.

"Each year we treat hundreds of cases of heatstroke in dogs and tragically, many of these prove to be fatal. The findings from the study show a higher risk of heatstroke in certain breeds — with extra caution being taken for flat-faced breeds." — Sophie Gilbert, Vet Surgeon, Vets Now

What this means practically: the 6pm summer walk you think is safe because the sun has dropped is, statistically, where the danger lives. Not the car park.

What Heatstroke Does to Your Dog's Body

Understanding why the fatality rate is so high requires understanding what heatstroke actually is physiologically.

Heatstroke begins when a dog's core body temperature rises above 104°F (40°C). At this point the body's normal cooling mechanisms (panting, vasodilation) are overwhelmed. Once temperature exceeds 106°F (41.1°C), organ damage begins — including to the brain, kidneys, and gastrointestinal tract.

The severity of heatstroke depends not just on how high the temperature peaks, but how long it stays elevated. This is why the window between "my dog seems a bit tired" and "my dog is in crisis" can be alarmingly short.

Knowing what to look for early is the difference between a vet visit and an emergency. We've covered the full symptom progression in our guide to dog overheating symptoms — it's the most important thing you can read alongside this.

Dog Heatstroke Prevention:

What the Research Says Actually Works

The Royal Veterinary College's official guidance, built directly on this research, comes down to one headline recommendation: cool first, transport second.

Most owners' instinct is to rush a dog to the vet immediately. The RVC says this is wrong. Time spent cooling the dog before transport is more important than transport speed - because lowering body temperature in the critical early window saves organ function. A 15-minute delay cooling your dog at home may save more of their life than a 15-minute head start on the drive to the clinic.

Here's what effective dog heatstroke prevention looks like in practice:

Before it happens:

• Walk your dog before 8am or after 8pm during warm months. Not 6pm. The pavement radiates heat for hours after the sun drops and your dog's body temperature is still working against ambient air temperature and humidity.

• Carry water. Dogs need to drink during exercise to support panting efficiency, not just after.

• Shorten walks before you think you need to. The 2024 data shows exercise-triggered cases aren't from marathon sessions - they're from normal walks on warm days.

• Invest in active cooling equipment for at-risk breeds. A dog cooling harness with gel ice packs drops ambient temperature against your dog's core, reducing the thermoregulatory workload before distress begins - not after.

During a walk:

• Watch for early signs (heavy panting, slow pace, seeking shade, refusing to move). These are not laziness. These are your dog's only way of telling you the cooling system is struggling.

• Stop before your dog shows obvious distress. By the time panting becomes laboured and gait is affected, you're already in a dangerous window.

• Take shade breaks, not just water breaks.

If you suspect heatstroke:

• Move your dog to the coolest available environment immediately.

• Apply cool (not ice cold) water to paws, armpits, groin, and neck — the areas with highest blood flow near the surface.

• Fan the dog to assist evaporative cooling.

• Get to a vet as fast as possible after starting cooling.

For a step-by-step emergency protocol, read our guide on how to cool down a dog fast.

The Gear That Makes a Real Difference

For breeds in the elevated-risk categories above — brachycephalic dogs, double-coated dogs, giant breeds, senior dogs — passive prevention measures alone may not be sufficient on warm days.

Active cooling gear works by introducing a cold surface to the areas where blood circulates closest to skin (the chest, neck, and torso) to help manage core temperature before the dog reaches the danger zone.

The Hoddogs Dog Cooling Harness Kit uses gel ice packs positioned against the chest and torso. You pre-freeze the packs, clip the harness on before a walk, and the cooling effect works continuously during exercise — the period the research identifies as the highest-risk window. For high-risk breeds, this is the difference between a walk and a safe walk.

And for bandana users: the Rebel Rag Dog Bandana uses a dry gel ice pack pocket against the neck - a key heat-exchange point.

The Final Bark

Here's the brutal truth the research gives us: heatstroke isn't something that only happens to neglectful owners. It happens on walks. On summer mornings. To fit, healthy dogs. To dogs whose owners are paying attention.

The difference between a dog that survives and one that doesn't often comes down to preparation — knowing which dogs are at risk before the heat arrives, knowing what to watch for before symptoms escalate, and having the tools to keep core temperature manageable during the highest-risk activity of all: exercise.

The study has been done. The data is in. 167,000 cases, peer-reviewed, published in the Veterinary Record. Now you know what it says.

Your dog is cool AF. Let's keep it that way.

Shop the Hoddogs Cooling Harness Kit

Quick Reference: Dog Heatstroke Risk at a Glance

Sources:

• Beard et al. (2024), Veterinary Record - VetCompass Emergency Care Study, 167,751 dogs, Royal Veterinary College

• O'Neill et al. (2020), Animals - "Dogs Don't Die Just in Hot Cars", VetCompass, 905,543 dogs

• O'Neill et al. (2016), Scientific Reports - Incidence and risk factors for heat-related illness in UK dogs

FAQ: Dog Heatstroke Prevention

What temperature is too hot to walk a dog?

There's no single universal threshold, but as a general guide: exercise caution above 75°F (24°C) for brachycephalic breeds and senior or overweight dogs; above 80°F (27°C) for most other dogs. Humidity matters as much as temperature — high humidity reduces panting efficiency. The safest rule: if it feels hot to you, it's working against your dog.

Which dog breeds are most at risk for heatstroke?

According to Beard et al. (2024) and multiple VetCompass studies, the highest-risk breeds are: French Bulldog, English Bulldog, Pug (brachycephalic group), Newfoundland, Chow Chow (both 15-17x more likely than Labradors), Golden Retriever, and Greyhound. Giant breeds over 50kg and elderly dogs over 12 years are also high-risk categories regardless of breed.

Is exercise really more dangerous than a hot car for dogs?

Yes, according to the data. The 2020 VetCompass study found exercise triggered 74.2% of heat-related illness events in dogs, while vehicle confinement caused just 5.2%. The 2024 Beard emergency care study found exercise responsible for 51.46% of emergency heatstroke cases. Exercise-induced heatstroke also carries the same fatality risk as vehicular heatstroke.

What is the survival rate for dog heatstroke?

In the 2024 emergency care study, the event fatality rate was 26.56% — meaning more than 1 in 4 dogs that presented to an emergency clinic with heatstroke did not survive. The 2016 primary care study found a 14.18% fatality rate. Dogs that receive cooling intervention before transport have better outcomes.

Why are Golden Retrievers at risk if they don't have flat faces?

Golden Retrievers, Huskies, and other double-coated breeds face a different mechanism. Their thick insulating coats trap hot air against the body, preventing heat dissipation during exercise. The coat that protects them in winter works against them in summer heat. This was confirmed across multiple VetCompass studies as a significant independent risk factor.

What should I do if my dog gets heatstroke?

Cool first, transport second - this is the RVC's official guidance. Move your dog to a cool environment, apply cool (not ice cold) water to high-blood-flow areas (paws, groin, neck, armpits), and fan them. Begin this process before driving to the vet, not instead of going. Every minute of cooling in the early window improves outcomes.

Can cooling gear actually prevent heatstroke?

Active cooling gear - harnesses with gel ice packs, cooling bandanas - can help manage core temperature during exercise, reducing the thermoregulatory workload in the period the research identifies as the highest-risk window. They work best as prevention during exercise, not as treatment after heatstroke has begun.