Dog Heatstroke: Symptoms, Treatment & Prevention

Dog heatstroke is a life-threatening emergency. If your dog is panting abnormally, struggling to breathe, becoming weak or confused, vomiting, staggering or collapsing after exercise or heat exposure, begin cooling them immediately and contact a vet.

Do not wait for your dog to collapse, do not delay while trying to take their temperature, and do not assume they are safe because their breathing begins to settle. Heatstroke can damage internal organs, and serious complications may not be immediately visible.

What is heatstroke in dogs?

Heatstroke develops when a dog produces or absorbs more heat than their body can release. Their body temperature rises, normal cooling mechanisms become overwhelmed, and tissues and organs can begin to suffer damage.

Dogs mainly regulate their temperature by panting. They can also lose some heat through their skin and paw pads, but they do not cool themselves by sweating across most of their body in the way humans do. Panting becomes less effective when:

• The surrounding air is hot or humid.
• Airflow is poor.
• The dog is exercising and producing additional body heat.
• The dog has a shortened airway or breathing problem.
• Excess body weight or a thick coat slows heat loss.
• The dog cannot move to a cooler place.

Heatstroke can develop after exercise or because a dog is trapped in a hot or poorly ventilated environment. It does not require a parked car, extreme sunshine or an official heatwave. UK research has repeatedly found exercise to be a leading cause of canine heat-related illness.

Heat stress, heat exhaustion and heatstroke

Terms such as heat stress, heat exhaustion and heatstroke are sometimes used to describe increasing levels of heat-related illness. In practice, these labels are not always used consistently.

For an owner, the most important point is not to decide precisely which stage a dog has reached. It is to recognise that the dog is becoming abnormally hot and to intervene before the condition worsens.

A useful way to think about heat-related illness is:

• Early concern: the dog is struggling to cope with the heat but remains alert and mobile.
• Worsening illness: breathing, behaviour, movement or digestion becomes abnormal.
• Severe heatstroke: the dog develops neurological signs, collapse, seizures, unconsciousness or evidence of serious internal injury.

Not every dog displays every sign, and symptoms do not always appear in a predictable order.

What are the signs of dog heatstroke?

A dog with heatstroke may initially look as though they are simply tired or panting after activity. The important questions are:

• Is the panting excessive for the activity and conditions?
• Is the dog’s breathing more difficult or noisy than normal?
• Is the dog behaving differently?
• Are the signs improving after exercise stops, or becoming worse?
• Are weakness, vomiting, confusion or poor coordination developing?

When heat exposure is possible, it is safer to stop the activity and begin cooling than to wait for proof that the dog has heatstroke.

Dog heatstroke signs at a glance

Early concern	Worsening concern	Severe emergency
Excessive or abnormal panting	Marked weakness	Collapse
Restlessness or inability to settle	Vomiting or diarrhoea	Seizures
Seeking shade, water or a cooler surface	Difficulty standing or poor coordination	Loss of consciousness
Excessive drooling	Confusion or disorientation	Severe breathing difficulty
Redder gums or tongue than usual	Breathing becoming more laboured	Bloody vomit or diarrhoea
Unusual slowing down	Symptoms continuing after exercise stops	Unresponsiveness

Dogs do not always show every sign or progress through these stages in order. If heatstroke is possible, begin cooling and contact a vet rather than waiting for more severe symptoms.

Early signs that a dog is getting too hot

Early or less severe signs may include:

• Panting more heavily than expected.
• Breathing faster, harder or more noisily.
• Restlessness, agitation or an inability to settle.
• Repeatedly seeking shade, water or a cooler surface.
• Excessive drooling.
• Redder gums or tongue than usual.
• A faster heartbeat.
• Becoming unwilling or unable to continue exercising.
• Unusual tiredness or slowing down.
• Vomiting or diarrhoea.

These signs are not exclusive to heatstroke, but the combination of heat exposure, excessive panting and a change in behaviour should be taken seriously. RVC guidance advises owners to act immediately because heat-related illness can progress rapidly into a life-threatening emergency.

Signs that the situation may be severe

Signs of severe heatstroke can include:

• Marked weakness.
• Difficulty standing.
• Staggering or poor coordination.
• Confusion or disorientation.
• Severe or distressed breathing.
• Collapse.
• Seizures.
• Loss of consciousness.
• Bloody vomit or diarrhoea.
• Unresponsiveness.

These signs require immediate cooling and emergency veterinary help.

Do not wait for severe symptoms before acting. Research reported by the Royal Veterinary College found that survival was much higher among dogs treated while heat-related illness was still mild than among dogs presenting with severe heatstroke. Those figures describe groups of dogs and cannot predict the outcome for an individual animal, but they strongly support early recognition and cooling.

Is heavy panting always heatstroke?

No. Dogs may pant because of:

• Recent exercise.
• Excitement.
• Anxiety.
• Pain.
• Fever.
• Breathing or heart disease.
• Certain medications.
• Being in a warm environment.

Normal post-exercise panting should gradually settle once the dog rests somewhere cool. Panting becomes more concerning when it:

• Appears excessive for the activity.
• Continues or worsens after exercise stops.
• Sounds noisy, harsh or distressed.
• Occurs with weakness, vomiting or diarrhoea.
• Occurs with abnormal gum colour.
• Is accompanied by confusion, staggering or collapse.
• Develops in a dog known to be at high risk.

You do not need to prove that the panting is caused by heatstroke before taking sensible action. Stop the exercise, move the dog somewhere cool, begin cooling if overheating is suspected and contact a vet for advice.

Signs do not always follow a fixed sequence

A dog may move from apparently mild signs to serious illness quickly. Others may show vomiting, weakness or neurological symptoms without every earlier sign being obvious.

Dogs can also hide discomfort or continue playing despite becoming dangerously hot. Highly driven dogs may keep chasing a ball, running or working after they should have stopped.

Judge the whole situation rather than waiting for a particular symptom:

• What has the dog been doing?
• How warm or humid is the environment?
• Is the dog in direct sunlight?
• Is there effective ventilation?
• Does the dog have known risk factors?
• Are the signs getting worse?

When in doubt, stop the source of heat and seek veterinary advice.

What should you do if your dog has heatstroke?

The safest immediate approach is:

Stop further heating, begin active cooling, call a vet and continue cooling during transport where practical.

The phrase “cool first, transport second” does not mean spending a long time cooling your dog before contacting a vet. It means that cooling should begin immediately rather than placing an uncooled dog into a vehicle and waiting until arrival at the surgery before anything is done.

Start cooling, call the veterinary practice as soon as possible and follow its instructions.

Stop further heating

Immediately:

• Stop walking, running, playing or working.
• Move the dog out of direct sunlight.
• Remove them from a hot car, conservatory, tent, room or other confined area.
• Move to shade or a cooler, well-ventilated place.
• Avoid making the dog walk farther than necessary.
• Remove heavy coverings that are trapping heat.

Remove equipment only when doing so is safe. A harness, coat or other item may be contributing to heat retention, but an unsecured and distressed dog could run into danger. Maintain control without wrapping or insulating the dog.

Start cooling immediately

Pour water that is cooler than the dog over the body. Cold tap water is suitable.

Keep the water away from the dog’s nose and mouth, particularly if they are breathing heavily, confused, weak or unconscious. Create airflow with a fan, breeze, open doors or air conditioning while the coat is wet. This supports evaporation and helps carry heat away.

Do not waste valuable time trying to find water at a particular “perfect” temperature. Current evidence does not support the old warning that cold water routinely causes shock in an overheated dog. Fast, effective cooling is important because the longer body temperature remains elevated, the greater the risk of harm.

Should you immerse the dog in water?

Cold-water immersion can be an effective cooling method for a young, healthy and conscious dog that is comfortable in water and can be handled safely.

Do not force immersion if the dog:

• Is unconscious.
• Is elderly or medically vulnerable.
• Has a relevant health condition.
• Is panicking or struggling.
• Cannot keep their head safely above water.
• Is too large or difficult to handle securely.

For these dogs, pour or spray water cooler than the dog over the body and combine it with airflow.

Should you put a wet towel over the dog?

No. Do not wrap or cover an overheated dog in a wet towel.

A towel over the body can warm up and hinder heat loss. Continue applying water directly to the dog and create airflow instead.

A dog may lie on top of a cool wet towel if useful, but the towel should not cover or encase the body.

Should you give the dog water to drink?

Offer drinking water, but do not force it into the dog’s mouth.

A dog that is distressed, confused, unconscious or struggling to breathe may inhale water. Cooling the body and obtaining veterinary help take priority.

Call a vet straight away

Contact your vet or the nearest emergency veterinary practice while cooling your dog.

Tell them:

• That you suspect heatstroke or overheating.
• What the dog was doing before the symptoms started.
• Where the dog was.
• Approximately how long the heat exposure or exercise lasted.
• Which signs you have observed.
• Whether the dog has collapsed, vomited or had a seizure.
• What cooling you have already started.
• Whether the dog has any relevant medical conditions.

Do not wait to see whether the dog makes a full recovery at home. A dog may appear cooler or more alert while internal complications continue to develop. RVC guidance advises veterinary assessment even when a dog appears to have improved, unless the veterinary team specifically tells the owner otherwise.

Transport safely while cooling continues

Use a cooled and well-ventilated vehicle.

Where possible:

• Turn on the air conditioning before putting the dog inside.
• Position the dog where cool air can reach them.
• Continue applying water where practical.
• Have another adult monitor and cool the dog.
• Keep the dog safely restrained without wrapping them in bedding.
• Drive directly to the veterinary practice.
• Follow any instructions the veterinary team gives you.

Take care when handling a dog that is distressed, confused, painful or having a seizure. Even a normally gentle dog may react unpredictably during an emergency.

Do not delay the journey once cooling has begun and veterinary transport is available. The aim is to combine immediate cooling with urgent professional care—not to choose one instead of the other.

What causes heatstroke in dogs?

Heatstroke is often associated with dogs being left in hot cars, but that is only one possible cause. In the UK, veterinary research has consistently shown that exercise is one of the most common triggers, even on days that many owners would not consider extremely hot.

Understanding how heatstroke develops can help you recognise risky situations before they become emergencies.

Exercise and overexertion

Many cases of canine heatstroke occur during or shortly after exercise.

Examples include:

• Walking during the warmest part of the day.
• Long hikes without adequate rest.
• Repeated ball throwing.
• Running beside a bicycle.
• Canicross or agility training.
• Vigorous play with other dogs.
• Excited zooming around the garden.

Exercise produces large amounts of body heat. If that heat cannot be lost quickly enough, body temperature continues to rise.

This can happen surprisingly quickly if:

• the weather is warm,
• humidity is high,
• there is little air movement,
• the dog is overweight,
• the dog has breathing difficulties,
• or the exercise is more intense than usual.

One important finding from UK research is that many exercise-related cases followed ordinary walks, not extreme sporting activity. Owners should therefore avoid assuming that only strenuous exercise creates a risk. If you’re unsure whether conditions are suitable for exercise, read our guide to is it too hot to walk my dog.

Hot cars and vehicles

A parked vehicle can become dangerously hot within a short period of time.

Even when outside temperatures seem moderate, the inside of a car can heat rapidly because sunlight passes through the windows and becomes trapped.

Opening a window slightly does not make a parked car safe.

Dogs should never be left unattended in a parked vehicle if there is any possibility of overheating.

Heatstroke can also develop during travel if:

• ventilation is poor,
• air conditioning fails,
• the dog is confined in direct sunlight,
• or the journey is unexpectedly delayed.

Planning ahead is especially important during summer travel.

Hot environments

Heatstroke is not limited to cars.

Dogs can also overheat in:

• conservatories,
• greenhouses,
• poorly ventilated rooms,
• sheds,
• tents,
• caravans,
• enclosed gardens with little shade,
• balconies,
• patios,
• poorly ventilated crates,
• grooming areas,
• or any place where heat builds faster than it can escape.

Indoor heatstroke is uncommon compared with exercise-related cases but is entirely possible, particularly during prolonged hot weather.

Heat can build up even without a heatwave

Many owners expect heatstroke to occur only during extreme temperatures.

In reality, several factors combine to influence risk:

• air temperature,
• humidity,
• direct sunshine,
• airflow,
• exercise intensity,
• excitement,
• body condition,
• coat type,
• underlying health,
• and how well the dog has adapted to warmer conditions.

A cloudy but humid day may present more risk than a sunny day with a cool breeze.

For this reason, there is no single outdoor temperature that guarantees safety for every dog.

Which dogs are most at risk?

Any dog can develop heatstroke.

However, some dogs become dangerously hot much more easily than others and require more conservative management during warm weather.

Flat-faced (brachycephalic) breeds

Dogs with shortened muzzles often struggle to lose heat efficiently because panting is less effective.

Examples include:

• French Bulldogs,
• English Bulldogs,
• Pugs,
• Boston Terriers,
• Shih Tzus,
• Boxers.

These breeds should be exercised particularly cautiously in warm conditions.

Overweight dogs

Body fat acts as insulation.

An overweight dog generally finds it harder to lose excess body heat and may tire sooner during exercise.

Maintaining a healthy body condition reduces heatstroke risk as well as improving overall health.

Puppies

Young dogs can become overexcited, fail to regulate their activity appropriately and may not recognise when they need to stop playing.

Owners should provide frequent opportunities to rest, drink and cool down.

Older dogs

Senior dogs may have:

• reduced cardiovascular fitness,
• arthritis limiting movement,
• heart disease,
• breathing disorders,
• or reduced ability to regulate body temperature.

Shorter, gentler exercise is often safer during warm weather.

Dogs with medical conditions

Dogs affected by:

• heart disease,
• respiratory disease,
• neurological disorders,
• obesity,
• or reduced mobility

may struggle to cope with heat and should be managed more cautiously.

If your dog has a chronic medical condition, ask your vet whether you should make any specific changes to exercise or summer routines.

Thick-coated and giant breeds

Large dogs generate considerable body heat during exercise.

Long or dense coats may slow heat loss in certain conditions, although clipping a coat is not automatically the answer for every breed.

Coat care should be tailored to the individual dog rather than assuming every long-haired breed should be clipped for summer.

Very active dogs

Working dogs, sporting dogs and highly driven individuals may continue running or chasing even when becoming dangerously hot.

These dogs often rely on their owner to recognise when activity should stop.

Does your dog’s temperature confirm heatstroke?

Many owners wonder whether they should take their dog’s temperature before deciding whether heatstroke is present.

In most situations, no.

If your dog is showing signs of heat-related illness, do not delay cooling while searching for a thermometer or trying to obtain a rectal temperature.

Clinical signs are far more important than obtaining a precise number.

Veterinarians may use body temperature as part of their assessment, but they also consider:

• breathing,
• heart rate,
• mental state,
• circulation,
• hydration,
• neurological signs,
• and the circumstances surrounding the illness.

A temperature around 40°C or above in an overheated dog is concerning, but owners should not use a temperature threshold as permission to delay action.

If your dog appears dangerously overheated:

• begin cooling,
• contact your vet,
• and travel for assessment.

How do vets treat dog heatstroke?

Veterinary treatment depends on how severely the dog has been affected.

After assessing your dog, the veterinary team may:

• continue controlled cooling,
• monitor body temperature,
• provide oxygen,
• administer intravenous fluids,
• perform blood tests,
• perform urine tests,
• monitor blood clotting,
• assess kidney and liver function,
• manage seizures if present,
• treat vomiting or diarrhoea,
• provide pain relief where appropriate,
• admit the dog for hospital care and monitoring.

Not every dog requires every treatment.

Dogs treated early may only need monitoring and supportive care.

More severely affected dogs may require intensive treatment over several days.

Heatstroke can affect multiple organs, including:

• the brain,
• kidneys,
• liver,
• lungs,
• heart,
• and gastrointestinal tract.

Some complications may not become obvious until hours after the initial overheating, which is one reason veterinary assessment remains important even when the dog seems brighter after cooling.

Can a dog recover from heatstroke?

Yes, many dogs do recover from heatstroke, particularly when owners recognise the problem early, begin cooling immediately and seek prompt veterinary treatment.

Unfortunately, heatstroke can also be fatal. The longer a dog’s body temperature remains dangerously high, the greater the risk of permanent damage to the brain and other vital organs.

One of the most encouraging findings from UK veterinary research is that dogs treated while still showing relatively mild heat-related illness have a much better chance of survival than those that reach severe heatstroke before treatment begins. This is why recognising the early signs and acting quickly is so important.

What happens after veterinary treatment?

Recovery depends on several factors, including:

• how high the dog’s body temperature became,
• how long they remained overheated,
• how quickly cooling started,
• their age and general health,
• and whether any organs were damaged.

Some dogs recover rapidly and return home the same day.

Others require:

• overnight monitoring,
• repeat blood tests,
• intravenous fluids,
• oxygen therapy,
• medication,
• or several days of hospital care.

Your vet may recommend temporarily restricting exercise while your dog recovers.

Watch for delayed complications

Even if your dog appears much better after cooling, continue following your vet’s advice.

Contact your veterinary practice immediately if your dog later develops:

• vomiting,
• diarrhoea,
• weakness,
• confusion,
• collapse,
• reduced appetite,
• breathing difficulties,
• changes in drinking or urination,
• or any other deterioration.

Heatstroke can continue affecting the body after the initial overheating has ended.

How can dog heatstroke be prevented?

Preventing heatstroke is far easier than treating it.

Although no plan removes all risk, a few sensible precautions greatly reduce the chance of an emergency.

Exercise at the right time

During warm weather:

• walk earlier in the morning,
• or later in the evening,
• reduce both distance and intensity,
• build in regular rest breaks,
• and be prepared to shorten or cancel the walk altogether.

Missing one walk is far safer than risking heatstroke.

If you do decide to walk your dog, check what pavement temperature is too hot for dogs before setting off, as hot surfaces can burn your dog’s paws even when the air temperature seems reasonable.

Always provide water

Fresh drinking water should always be available before, during and after exercise. If you’re travelling or walking any distance, carry water for both yourself and your dog. If you’re unsure how much water your dog should drink each day, our complete hydration guide explains how to estimate their daily water needs and the factors that affect them. Offer drinks regularly rather than waiting until your dog appears desperately thirsty.

Plan for shade and ventilation

Whether at home, on holiday or travelling:

• provide genuine shade,
• maximise airflow,
• avoid enclosed hot spaces,
• and ensure your dog always has somewhere cooler to rest.

If you’re planning a journey, our complete guide to travelling safely with a dog explains how to prepare for hot-weather travel, choose suitable transport and reduce heat-related risks before you set off.

Remember that shade moves during the day.

A shaded area at 10 am may be in full sun by lunchtime.

A well-designed dog-friendly garden should provide dependable shade, fresh water and a cooler place to rest throughout the day.

Be cautious with high-risk dogs

Dogs at increased risk should have more conservative routines.

This includes:

• flat-faced breeds,
• overweight dogs,
• older dogs,
• puppies,
• dogs with heart or breathing problems,
• and dogs recovering from illness.

They may need shorter walks, more frequent rests and greater supervision.

Never leave a dog in a parked vehicle

Even a short stop can become dangerous.

If your dog cannot safely accompany you when you leave the vehicle, they should remain at home instead.

Watch your dog—not just the weather forecast

Many owners focus only on the outside temperature.

A better question is:

How is my individual dog coping right now?

If your dog appears unusually tired, begins panting excessively or starts slowing down, change your plans immediately.

Could these symptoms be something other than heatstroke?

Yes.

Panting, weakness and vomiting are not unique to heatstroke.

Other conditions may cause similar signs, including:

• heart disease,
• breathing disorders,
• poisoning,
• seizures,
• pain,
• gastrointestinal illness,
• anxiety,
• or severe car sickness.

If your dog became unwell after swimming in a lake or reservoir, blue-green algae poisoning is another possibility.

However, if heat exposure is even remotely possible, it is safest to begin cooling your dog while seeking urgent veterinary advice.

If your dog has localised redness, sore skin or blistering after sun exposure rather than whole-body illness, see our guide to recognising and treating dog sunburn.

Trying to decide exactly which condition is responsible should never delay emergency treatment.

Dog heatstroke emergency checklist

Use this quick checklist if you suspect your dog is overheating.

• Stop exercise immediately.
• Move your dog into shade or a cooler, well-ventilated place.
• Pour water cooler than your dog over the body.
• Avoid pouring water over your dog’s face, nose or mouth.
• Create airflow using a fan, breeze or air conditioning.
• Call your vet or emergency veterinary practice immediately.
• Continue cooling while travelling where practical.
• Offer a bowl of drinking water if your dog is conscious, but never force them to drink.
• Do not wrap your dog in a wet towel.
• Do not wait for collapse or for a temperature reading before acting.

Frequently asked questions

Can dogs get heatstroke indoors?

Yes.

Heatstroke can occur indoors if ventilation is poor or indoor temperatures become excessively high.

Exercise inside a warm building may also contribute.

Can dogs get heatstroke without being in direct sunshine?

Yes.

Exercise, humidity, poor airflow and hot indoor environments can all lead to dangerous overheating.

A dog does not need to be lying in direct sunlight to develop heatstroke.

Should I use cold or lukewarm water?

Current UK veterinary guidance supports cooling an overheated dog immediately using water cooler than the dog’s body.

Cold tap water is appropriate.

Do not delay cooling while trying to obtain lukewarm water.

Should I cover my dog with a wet towel?

No.

Wrapping a wet towel around an overheated dog can reduce heat loss.

Apply water directly to the dog and create airflow instead.

Can a dog recover without seeing a vet?

Even if your dog appears much better after cooling, they should still be assessed by a veterinary professional unless your vet specifically advises otherwise.

Internal complications are not always immediately obvious.

How long does heatstroke last?

Recovery varies enormously.

Some dogs recover quickly after prompt treatment.

Others require several days of hospital care and monitoring.

The outcome depends on how severe the heatstroke became and how quickly treatment started.

Bottom line

Dog heatstroke is one of the most serious warm-weather emergencies a dog owner can face, but early action can make a huge difference.

If you think your dog may be overheating:

• stop the heat exposure,
• begin cooling immediately,
• contact your vet,
• and continue cooling while travelling for professional assessment.

Do not wait for collapse or for every classic symptom to appear.

Acting early gives your dog the best possible chance of making a full recovery.