Heatstroke in Dogs: Signs, First Aid, Prevention and Risks for Working Dogs

Last evidence review: 11 July 2026

Heat-related illness can affect any dog. It can develop during exercise, in hot or poorly ventilated environments, during transport or after prolonged exposure to heat. It does not only occur inside parked vehicles or during extreme temperatures.

Dogs regulate body temperature differently from humans. They rely mainly on panting to lose heat and have only a limited ability to cool themselves through sweating. When a dog produces or absorbs heat faster than it can dissipate it, body temperature can continue to rise and overheating may progress to heatstroke.

The condition can become life-threatening.

Key Point: Heatstroke in dogs can develop through exercise, environmental heat, humidity, poor airflow, transport conditions and inadequate recovery. At the first signs of overheating, stop activity, begin cooling immediately and seek veterinary advice. Current Royal Veterinary College guidance follows the principle: cool first, transport second.

What Is Heatstroke in Dogs?

Heatstroke is a potentially life-threatening form of heat-related illness that occurs when a dog’s body accumulates heat faster than it can dissipate it.

The problem is not simply that the dog becomes “too hot”. As body temperature continues to rise, heat stress can begin to affect circulation, neurological function, blood clotting and vital organs.

In severe cases, heatstroke can lead to collapse, seizures, organ failure and death.

The Royal Veterinary College guidance on heatstroke in dogs states that it does not always have to be particularly hot for an animal to develop heatstroke. Excessive exercise in warm weather and exposure to warm, humid or poorly ventilated environments can cause animals to overheat quickly.

How Do Dogs Cool Themselves?

Dogs regulate heat primarily through panting.

As a dog pants, air moves rapidly across moist surfaces in the mouth and respiratory tract, supporting evaporative heat loss.

Dogs also have sweat glands in their paw pads. However, because the surface area is small, sweating makes only a limited contribution to cooling compared with panting.

Heat can also be lost through increased blood flow to areas of the body where it can be dissipated more effectively.

The effectiveness of these mechanisms depends on several factors, including:

• environmental temperature;
• humidity;
• airflow and ventilation;
• exercise intensity;
• direct sunlight;
• surface temperature;
• breed and body shape;
• bodyweight;
• health conditions;
• coat type;
• acclimatisation;
• hydration;
• recovery between periods of activity.

This is why air temperature alone does not determine whether a dog is safe.

Can Dogs Overheat Without Extreme Temperatures?

Yes.

A dog can overheat even when the weather does not appear exceptionally hot.

Exercise itself generates body heat. Humidity can reduce the effectiveness of evaporative cooling. Poor airflow can slow heat loss. Direct sunlight, warm buildings, vehicles and hard surfaces can add further thermal load.

A dog can therefore become overheated through the combined effect of several moderate risk factors rather than one extreme condition.

For example, a physically active dog exercising in warm, humid weather with limited airflow may be at greater risk than a resting dog exposed to the same air temperature.

Do not assess heat risk from the weather forecast alone. Assess the individual dog, the activity, the environment and the quality of recovery together.

What Are the Early Signs of Overheating in a Dog?

Early recognition matters because heat-related illness can progress rapidly.

Warning signs may include:

• unusually heavy, persistent or increasingly noisy panting;
• restlessness or agitation;
• actively seeking shade or water;
• excessive drooling;
• thickened saliva;
• red gums or tongue;
• reduced energy;
• reluctance to continue walking or exercising;
• weakness;
• unsteady movement;
• vomiting;
• diarrhoea;
• an increased heart rate.

One of the most important indicators is a change from that dog’s normal behaviour and recovery pattern.

A dog that normally settles quickly after exercise but suddenly continues to pant heavily, appears restless, moves differently or takes much longer to recover should not be assumed to be merely tired.

Waiting for dramatic signs such as collapse or seizures means the opportunity for earlier intervention may already have been lost.

When Does Heatstroke Become a Medical Emergency?

Advanced signs may include:

• marked lethargy;
• confusion or disorientation;
• severe weakness;
• collapse;
• seizures;
• loss of consciousness;
• blood in vomit;
• blood in diarrhoea.

These signs indicate a medical emergency.

Heatstroke can affect multiple body systems. Severe cases may involve neurological dysfunction, impaired circulation, kidney injury, gastrointestinal damage, abnormal blood clotting and organ failure.

The exact number of dogs that die from heat-related illness across the UK each year is not known.

However, a large UK VetCompass study published in Scientific Reports examined primary-care veterinary records from 905,543 dogs across 886 UK veterinary clinics.

Researchers identified 395 heat-related illness events during 2016, of which 56 resulted in death, giving an event fatality rate of 14.18%.

This does not mean that only 56 dogs died from heat-related illness across the entire UK that year. The figure represents deaths recorded within the study population and should not be interpreted as an official national mortality total.

The full peer-reviewed research is available in Scientific Reports: Incidence and risk factors for heat-related illness in UK dogs.

Why this matters: In one of the largest UK studies of canine heat-related illness, approximately one in seven recorded heat-related illness events resulted in death. The practical lesson is clear: do not wait for collapse before acting.

What Should You Do If a Dog Is Overheating?

Current UK guidance is clear: cool first, transport second.

1. Stop Further Activity Immediately

Do not ask the dog to finish the walk, complete another exercise or return a long distance under its own effort.

2. Move the Dog Away From the Heat Source

Use shade or a cool, well-ventilated environment where available.

3. Begin Cooling Immediately

The Royal Veterinary College recommends cold-water immersion as an effective approach for young, healthy dogs.

For older dogs or dogs with underlying health conditions, pouring water cooler than the dog’s body temperature over the dog and combining this with air movement may be more appropriate.

4. Create Airflow

Use a fan, air conditioning, breeze or other suitable airflow where available.

Air movement supports evaporative cooling.

5. Offer Water Without Forcing the Dog to Drink

Allow access to water, but do not force water into the dog’s mouth.

6. Seek Veterinary Advice as Soon as Possible

Even where a dog appears to improve after initial cooling, more serious effects may not be immediately apparent.

Veterinary advice should still be sought where overheating or heatstroke is suspected.

What Should You Avoid Doing?

Do not delay cooling while searching for perfect equipment, perfect water temperature or an ideal location.

The priority is to stop further heating and begin effective cooling.

Do not place wet towels over the dog’s body. The RSPCA guidance on recognising and treating heatstroke in dogs advises that wet towels placed over a dog can trap heat.

A wet or damp towel may be placed beneath a dog and re-wetted regularly, but it should not be draped over the animal.

Do not force water into a dog’s mouth.

Do not pour water over the head of a dog already struggling to breathe.

Do not assume the danger has passed simply because the dog appears better after a few minutes.

Serious complications may not be immediately visible.

Which Dogs Are at Greater Risk of Heat-Related Illness?

Any dog can overheat, but some dogs have greater susceptibility.

Higher-risk groups include:

• flat-faced or brachycephalic breeds;
• overweight dogs;
• very large or heavy dogs;
• dogs with thick coats;
• very young dogs;
• older dogs;
• dogs with pre-existing airway, lung or heart conditions;
• dogs that are unfit or poorly acclimatised to heat and exercise.

The UK VetCompass study found that brachycephalic dogs had more than twice the odds of heat-related illness compared with mesocephalic dogs in the study’s multivariable analysis.

Dogs weighing more than 50 kg also had higher odds of heat-related illness than dogs weighing under 10 kg.

However, population-level risk factors should not be interpreted to mean that a dog outside these groups is safe.

A fit, healthy dog can still overheat if workload, environment, humidity, direct heat, airflow and recovery conditions combine unfavourably.

Can Dogs Overheat at Night?

Yes.

Night-time conditions can reduce direct solar exposure, but they do not automatically remove heat risk.

Buildings, vehicles, concrete and asphalt may retain heat after hot daytime conditions.

Warehouses, garages, vacant properties and enclosed spaces may remain warm and poorly ventilated.

Exercise also continues to generate body heat regardless of the time of day.

Heat risk should therefore be assessed from actual environmental conditions and the individual dog’s response rather than simply whether the sun has gone down.

Heatstroke and Overheating in Working Dogs

Working dogs can face a different heat-risk profile from ordinary pets.

Police dogs, detection dogs, military working dogs, search dogs, sporting dogs and working security dogs may perform repeated physical activity, work in unfamiliar environments, travel between locations and remain highly motivated despite increasing physical strain.

A working dog may also move between substantially different environments during the same period of work.

For example, a security dog might patrol an exposed outdoor site, enter a poorly ventilated building, return to a vehicle, rest briefly and then begin another patrol.

The risk can therefore be cumulative.

A dog that coped well with the first period of activity cannot automatically be assumed to be equally capable of completing the next one under changed conditions.

A working dog’s willingness to continue is not proof that the dog is coping safely.

Highly motivated dogs may continue to move, search or engage while thermal strain is increasing.

For that reason, willingness to continue should never be used as the sole indicator that a dog is safe to keep working.

This can be especially relevant on large construction sites, industrial premises and exposed external areas where shade, airflow, surface temperature and patrol distances may vary significantly.

Handlers should assess:

• panting;
• breathing pattern;
• behaviour;
• movement;
• coordination;
• responsiveness;
• workload already completed;
• environmental conditions;
• recovery speed;
• vehicle conditions;
• access to water;
• airflow and ventilation.

The Colosseum K9 HEATR Working Dog Risk Check

The Colosseum K9 HEATR Working Dog Risk Check is an operational framework designed to help handlers consider five factors that may contribute to heat load:

HEATR Principle: Working-dog heat risk should not be judged by air temperature alone. The dog, workload, environment, transport conditions and quality of recovery should be considered together.

H — Heat and Environment

Consider more than the reported air temperature.

Assess direct sunlight, humidity, radiated heat from buildings or machinery, shade availability, enclosed areas, hot asphalt, concrete and artificial surfaces.

A large open site can create a very different heat exposure from a shaded perimeter. A poorly ventilated building can create another risk profile entirely.

E — Exertion and Workload

Not all activity creates the same physical demand.

Consider exercise intensity, duration, search work, repeated movement, excitement and previous exertion.

A short intensive search can create a different thermal load from steady walking.

Repeated activity without sufficient recovery can progressively increase risk.

A — Airflow and Ventilation

Air movement supports heat loss.

Assess natural airflow, wind conditions, indoor ventilation, vehicle ventilation and the environment in which the dog is recovering.

A shaded area with good airflow may provide much better recovery conditions than a stationary enclosed vehicle or poorly ventilated building.

T — Transport and Confinement

Transport should be treated as part of the dog’s overall heat exposure.

Consider vehicle temperature, ventilation, journey length, whether the vehicle is stationary, how recently the dog exercised and whether genuine recovery is occurring.

The period immediately after exertion deserves particular attention because the dog may still be dissipating heat generated during activity.

R — Recovery

Recovery is not simply the absence of collapse.

The handler should assess whether breathing is settling, whether behaviour is returning to normal, whether the dog is coordinated, whether the dog is responsive and whether environmental conditions are supporting cooling.

If recovery is slower than expected, that should influence any decision about further activity.

The HEATR Working Dog Risk Check is an operational decision-making framework developed by Colosseum K9 Ltd. It is not a veterinary diagnostic tool, a clinically validated scoring system or a substitute for veterinary assessment.

The Recovery Question Every Handler Should Ask

Is this dog genuinely recovering, or has the activity simply stopped?

Those are not the same thing.

Standing still does not automatically mean the dog’s thermal load has normalised.

A dog resting in a hot, poorly ventilated vehicle or enclosed area may have stopped exercising without gaining an effective opportunity to lose heat.

Recovery should therefore be actively assessed.

The handler should consider:

• Is breathing settling?
• Is behaviour returning to normal?
• Is the dog responsive?
• Is the dog coordinated?
• Are environmental conditions helping or hindering cooling?

Where the answer is uncertain, further work should not be treated as automatic.

A Practical Heat-Risk Checklist for Working Dogs

• Assess HEATR: Heat, Exertion, Airflow, Transport and Recovery.
• Check the dog, not only the weather forecast.
• Account for workload already completed.
• Provide access to fresh water.
• Identify suitable shade and recovery areas.
• Consider heat retained by asphalt, concrete and buildings.
• Assess vehicles before placing the dog inside.
• Watch for changes from the dog’s normal panting, behaviour and movement.
• Allow recovery to be determined by the individual dog and conditions, not only by a fixed timetable.
• Stop work and begin cooling at the first concerning signs.
• Seek veterinary advice where overheating or heatstroke is suspected.

Prevention should begin before the dog shows obvious distress. Once abnormal signs appear, the priority changes from maintaining activity to protecting the dog.

Frequently Asked Questions

Can a dog get heatstroke when the weather is not extremely hot?

Yes. Dogs can develop heat-related illness through exercise and in warm, humid or poorly ventilated environments. Ambient temperature alone does not determine risk.

Do dogs sweat through their paws?

Yes. Dogs have sweat glands in their paw pads. However, because the surface area is small, sweating contributes only a limited amount to cooling. Dogs rely primarily on panting and other heat-dissipation mechanisms.

Can dogs overheat during exercise?

Yes. Exercise generates body heat and is an important trigger of canine heat-related illness. Risk may increase further with humidity, direct heat, poor airflow or insufficient recovery.

Can a working dog overheat even if it still wants to continue?

Yes. Willingness to continue should not be used as the sole measure of safety. The handler should assess breathing, behaviour, movement, workload, environmental conditions and recovery.

What is the first thing to do if a dog is overheating?

Stop further activity and begin cooling immediately. Current Royal Veterinary College guidance follows the principle “cool first, transport second”, while also seeking veterinary advice as soon as possible.

Should you put a wet towel over an overheating dog?

No. The RSPCA advises against placing damp towels directly over a dog’s body because they can trap heat.

Should an overheated dog still see a vet if it appears to recover?

Veterinary advice should still be sought. More serious effects of heatstroke may not be immediately apparent, even if the dog initially appears to improve.

How many dogs die from heatstroke in the UK each year?

The exact UK-wide annual number is not known. However, a large VetCompass study of more than 905,000 dogs identified 395 heat-related illness events in 2016, of which 56 resulted in death, giving an event fatality rate of 14.18%.

This was a study-population figure, not an official national total for all UK dogs.

Is there one temperature at which dogs should automatically stop exercising?

There is no single ambient temperature that accurately determines safety for every dog and every situation.

Risk depends on the individual dog, workload, humidity, direct heat exposure, airflow, fitness, acclimatisation, hydration, transport and recovery conditions.

Sources and Evidence Base

This article was developed using current guidance from the Royal Veterinary College on heatstroke prevention, symptoms and first aid; RSPCA guidance on recognising and treating heatstroke in dogs; and the peer-reviewed UK VetCompass study “Incidence and risk factors for heat-related illness (heatstroke) in UK dogs under primary veterinary care in 2016”, published in Scientific Reports.

Key sources:

• Royal Veterinary College — Heatstroke in dogs and cats
• RSPCA — How to recognise and treat heatstroke in dogs
• Hall EJ, Carter AJ, O’Neill DG. Incidence and risk factors for heat-related illness in UK dogs under primary veterinary care in 2016. Scientific Reports. 2020.

The HEATR Working Dog Risk Check is an operational decision-making framework developed by Colosseum K9 Ltd. It is not a veterinary diagnostic tool or a clinically validated heat-risk scoring system.