Heatstroke in Dogs

LAST UPDATED 14 December 2023

This article is written by Pet Circle veterinarian, Dr Brittany Ward BVSc

When we think of Summer with our dogs, we often think of beach trips, fun in the sun and Christmas celebrations. Have you thought about heatstroke though? Overdoing it with your dog in the hot weather can cause a potentially life threatening rise in their body temperature and land them with a hospital stay. Heatstroke is a medical emergency.

This article looks at Heatstroke, how it occurs, what the signs are and how you can prevent it from happening to keep your dog happy and healthy during the hot months ahead.

Understanding Heatstroke
Signs and Symptoms of Heatstroke
Causes of Heatstroke
Diagnosis of Heatstroke
Treatment of Heatstroke
Recovery and Management Post-Heatstroke
Preventing Heatstroke
Heatstroke FAQs

Understanding Heat Stroke

Heatstroke is a common term used to describe hyperthermia, or a body temperature that has risen above the normal level. A dog's normal body temperature is 38.0-39.0 degrees celsius and temperatures higher than this are considered abnormal, warranting intervention. If your dog's body temperature exceeds 41.1 degrees, the body's organs start to fail and neurological symptoms can present.

Our dogs do not sweat the same way we do, they only have a limited number of sweat glands between their paws. Instead, their primary method of cooling is by panting. When panting is insufficient to cool them, their body temperature can quickly rise, leading to hyperthermia. Panting is most effective when the ambient temperature is 32 degrees Celsius and can actually increase body temperature during high humidity (greater than 80%). Panting is a form of evaporative cooling, meaning that water is also lost during the process and it can lead to dehydration if excessive.

Heatstroke can progress rapidly and can cause death in as little as 15 minutes, so it is important to monitor your dog for any signs and respond quickly. Every second counts and the longer your dog's temperature is raised the more severe effects can be. The longer the body temperature is elevated and the higher the temperatures, the higher the risk for long term health problems or death.

Hyperthermia is classified into three categories depending on its severity:

Heat Stress
Heat stress often goes unnoticed as it is associated with increased thirst and panting. Dogs are still aware and able to move around.

Heat Exhaustion
Heat exhaustion is a more severe form of heat stress where dogs have significantly increased thirst, heavy panting, weakness and may collapse. They are mentally aware, but often too lethargic to respond or move around.

Heatstroke is defined by a body temperature higher than 41 degrees Celsius and is at the point where organs will begin to fail and neurological dysfunction can occur. It is characterised by more severe symptoms and requires immediate cooling and veterinary treatment.

Signs and Symptoms of Heatstroke

It is important to recognise heatstroke quickly to ensure the best outcome as it can quickly progress to death. There are a number of signs and symptoms that you can look for in your dog.

Early signs of heatstroke can include:
  • Increased body temperature
  • Heavy panting or difficulty breathing
  • Restlessness, agitation or shade seeking
  • Excessive drooling
  • Change in gum colour to bright red or bluish-purple
As the condition worsens, signs can progress to include:
  • Vomiting
  • Diarrhoea (may include blood)
  • Increased heart rate
  • Lethargy or collapse
  • Dizziness - may present as a staggering gait
  • Confusion
  • Muscle tremors
  • Seizures
  • Becoming unresponsive or unconscious

Causes of Heatstroke

There are many possible reasons why your dog's temperature may become elevated and any dog may be affected by heatstroke at any time of year. We can group the causes into two main categories though.

Environmental Factors

Environmental factors are those around us that affect our body temperature; such as the summer heat and humidity. Factors such as ventilation, shade, access to water, excessive exercise and enclosed spaces can all increase your dog's risk of heatstroke. Your pet may also be more susceptible to the heat if they have not yet acclimatised to the area you live in; they can take up to 60 days to acclimatise.

One of the leading causes of heatstroke is leaving dogs in the car without adequate ventilation, which can allow their temperature to rise within minutes. Similarly, being enclosed in a house or garage without air conditioning can also cause heatstroke. Even leaving them in an enclosure or yard without adequate shade, ventilation or water access could put your dog at risk.

If your dog requires to be muzzled for any extended period of time and has an incorrectly fitting muzzle, they may not be able to pant correctly, leading to hyperthermia.

Predisposing Internal Factors

Internal factors are any factor related to your dog, particularly in relation to their breed and health status. These are physical features or illnesses that may predispose your dog to heatstroke.

For example, puppies and senior dogs are predisposed to heatstroke.

Some dog breeds are more likely to experience heatstroke, including large breed dogs and those with thick or long coats that can retain heat, such as Huskies and Pomeranians.

Brachycephalic (short-nose or flat-faced breeds) are overrepresented in heatstroke cases. This includes, French Bulldogs, Pugs and Boxers. These breeds have small, narrow nostrils, elongated soft palates and narrow airways that can make it difficult for them to self cool. They are 146% more likely to experience heatstroke compared to longer nosed breeds.

Overweight and obese dogs have a significantly increased risk of heatstroke because fat acts as an insulator and they generate excess heat during exercise, tiring more quickly. Overly active, working and hunting dogs like Labradors and Kelpies are also predisposed, particularly if they continue to be active and exercise for prolonged periods of time or during the heat of the day.

A number of health conditions can also increase the risk of heatstroke, such as heart disease and neurological disorders. Because canine cooling is heavily reliant on the respiratory system, respiratory disorders, like laryngeal paralysis or tracheal collpase are also predisposing factors. Infections causing fever (pyrexia) and seizures or tremors can also raise the body temperature, progressing to hyperthermia.

Diagnosis of Heatstroke

Your veterinarian will make a diagnosis of heatstroke following an examination based on their symptoms, a history of exposure and their body temperature. Information you provide to your vet about the events preceding your dog's symptoms can be critical for making an accurate diagnosis.

Remember that health conditions such as infection and seizures can also raise the body temperature and your vet will want to rule out these as an underlying cause for their hyperthermia.

Treatment of Heatstroke

Heatstroke can be fatal and is considered a medical emergency! Your dog requires immediate attention and the sooner they get to a vet, the better their prognosis. However, you will need to start the cooling process before transporting your dog.

First Aid

If your dog is showing any of the above signs of hyperthermia, follow the below steps to help your dog start cooling down on the way to the vet clinic.

First aid steps:
  • Remove your dog from the source of the heat and move to somewhere cool.
  • Use a bucket or hose to pour water over them, avoiding their face. This water should be cooler than your dog, but NOT ice-cold.
  • Place them in front of a breeze, fan or air conditioning (at room temperature). The air conditioning in your car or an open car window are great options. Air flow combined with wetting them down promotes evaporative cooling.
  • Offer them water, ideally small sips.
  • Call your vet to let them know you are coming in and transport your dog to the clinic.

Veterinary Treatment

Once you arrive at the clinic, your vet will examine your dog and start or continue emergency cooling. They will start intravenous fluids to manage dehydration, shock and cool the body internally. Oxygen therapy will also be started.

For patients with respiratory difficulties or that are unconscious, anaesthesia and intubation may be used to ensure sufficient oxygen intake. Gastroprotectants or anti-nausea medications may be started for patients with vomiting and/or diarrhoea. Antibiotics may also be given to prevent a secondary infection. If required, your vet may also use cardiac medications.

Once cooling is in effect, your vet may recommend blood tests to assess the level of dehydration, look for clotting issues, assess organ function and determine the success of treatment. Prolonged hyperthermia can lead to clotting disorders and internal bleeding, so it is important to assess for these. If your dog has developed clotting problems, a blood or plasma transfusion may be required.

Heatstroke DONT'S

If your dog has heatstroke, NEVER use ice or ice water to cool them down. Ice and cold water will cause the blood vessels to constrict, retaining heat. Room temperature or cool water is best. If you are using air conditioning, this should also be kept at a comfortable, ambient temperature, such as 24-26 degrees Celsius to avoid cooling too quickly. Cooling too quickly can cause Hypothermia.

NEVER place a wet towel or cloth over your dog. These will absorb the heat from their body and create humidity, further raising your dog's temperature.

Recovery and Management Post Heatstroke

Once your dog has been cooled down, they will be hospitalised and closely monitored. Depending on the severity of the heatstroke, they may remain in Intensive Care until they have fully recovered. Early diagnosis and prompt, aggressive treatment are essential factors in determining prognosis. Heatstroke is generally considered to have a poor prognosis and because of the severe effects on the body, may be fatal or cause permanent damage even despite treatment.

Temperatures higher than 41 degrees Celsius or prolonged high temperatures can denature (breakdown) the proteins in cells and cause cellular damage. Proteins are essential for cell structure and many of our body functions, so their breakdown can lead to multiple organ failure and systemic shock. The more organs affected, the poorer the prognosis for the patient.

The higher the temperature your pet's body elevates to and the longer they are exposed impacts the likelihood and severity of the above systemic effects. The first 24 hours are the most critical, and pets surviving this period are likely to recover. Most surviving cases do recover without long term complications. Your dog will likely remain in hospital for 2-3 days, up to a week in more severe cases.

Once your dog is discharged, they will need lots of rest, to be kept at a comfortable temperature and plenty of TLC, for at least the first two weeks. Your vet may also request to do repeat blood tests 1-2 weeks post treatment to assess if any permanent damage has occurred and if any ongoing care is required.

Pets that have experienced heatstroke are susceptible to repeat episodes. Increased body temperatures can damage the natural temperature control system in your dog's body. This means they can no longer regulate their body temperature as well as before and the body temperature could easily elevate if they are in a hot environment. Ongoing prevention is even more important for past heatstroke patients.

Preventing Heatstroke

Preventing heatstroke is all about keeping your pet cool! Prevention is important for all dogs, but especially if you have a high risk breed. Here are some simple tips for preventing heatstroke in your dog.

How to prevent heatstroke:
  • Never leave your pet in a parked car
  • Never leave your pet inside a hot closed house or garage
  • Plan your trips to keep your car cool and provide water
  • Ensure your dog always has access to cool, fresh water
  • Encourage your dog to stay hydrated
  • Ensure your dog always has access to shade
  • Keep your dog in a well ventilated area
  • Walk your dog in the morning or late evening when it is cooler - especially brachycephalic breeds
  • Avoid walking on hot surfaces, such as sand, bitumen and concrete
  • Get dogs with long coats, like Poodles, clipped to prevent heat retention
  • Groom your dog, especially long haired breeds, regularly to remove loose fur and prevent matting
  • Provide access to cooling, such as water, cooling mats, and cooling vests

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Providing Enrichment and Exercise

Even though it is hot out, your dog still needs plenty of mental and physical stimulation to prevent them resorting to destructive behaviours for entertainment. So what activities can you do without risking heatstroke?

Scent Games

Scent games are a great indoor activity that is mentally challenging for your dog and a lot of great fun to play! Dogs love to engage in this kind of training as it simulates their natural hunting instincts and it's a great way to strengthen your bond with your dog. There are lots of scent game options, such as Seek, Find The Food and Identify the Smell, you just have to start searching and training. Who knows, your dog may even be able to find your house keys next time you lose them!


Why not try swimming? Swimming is an excellent summer activity. Avoid going in the hottest part of the day or use a pool that has been kept in the shade to help your dog cool down. Swimming is also great for assisting weight loss and providing low impact exercise for arthritis.

Keep in mind if you have a Brachycephalic, or pushed in face, breed, Swimming may not be a safe activity for them. Dogs will need to hold their head above water to continue to breathe while swimming, but for Brachycephalic breeds this may reduce their airflow. Water play with a sprinkler or a shallow body of water would be a great, safer alternative.

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Interactive Toys and Puzzles

Puzzles and interactive toys are the perfect way to keep your dog occupied while they are cooped up on a hot day. These activities provide mental stimulation, which is more tiring than physical activity, as well as gentle exercise. They can keep your dog distracted for an extended period of time, within the comfort of your own home or in a shaded area of the yard.

Top Recommended Puzzle Feeders:

Ice and Frozen Treats

Have you ever given your dog an ice-cube before? Ice-cubes can be a very interesting object for dogs. Not only can they be used to cool their water and mouth down, but they can also be great toys! Many dogs will initially be curious and investigate the ice-cube. They may also try to play with it, biting at it, pawing at it and chasing it as it goes skidding across the ground.

Frozen treats are also a great option for providing mental stimulation that helps to keep your pet cool. You could fill a Kong or lickmat with your pup's favourite wet food or paste treat to provide engaging, and cooling enrichment throughout the heat of the day.

Heatstroke FAQs

Can I treat heatstroke at home?

Heatstroke is a medical emergency and cannot be treated at home. You may be able to start the cooling process before getting to the vet, but your pet should always be seen by a vet if they are showing signs of heatstroke.

Without veterinary care, heatstroke can be rapidly fatal or cause long term health problems.

What should you do if your dog is showing signs of heatstroke?

If your dog is showing signs of heatstroke:
•Remove them from the heat
•Starting cooling them down
•Call your local vet or emergency clinic
•Take your dog in to to the vet

Can heat stress cause diarrhoea?

Yes, diarrhoea can be a sign of heatstroke. Sometimes the diarrhoea may also contain blood as the intestinal lining breaks down or as a result of clotting disorders caused by high body temperatures.

How long does heat stroke last?

Heatstroke persists until cooling is started and normal body temperature is restored or fatality occurs. On average, death will occur after one hour of hyperthermia without medical intervention. However, it can occur in as little as 15 minutes, depending on how high your dog's temperature is.

After treatment is started, minor cases may be able to go home within a couple of hours. More severe cases may require more intensive, long term treatment and management though. Some dogs may remain in hospital for 2-3 days or more if they have complications.

Can heat stroke cause seizures?

Yes, heatstroke can cause seizures. Extreme temperatures can damage cells in the brain and nerve cells, leading to seizures, as well as other neurological signs, such as dizziness, staggered gait, disorientation and muscle tremors.

Does heat stroke cause permanent damage?

Most dogs will recover quickly from heatstroke and without ongoing health concerns given they are provided with prompt treatment. However, heatstroke does have the potential to cause permanent damage depending on how high the temperature was, how long it was elevated for and the health status of the dog prior to heatstroke.

Body temperatures higher than 41 degrees Celsius will start to break down enzymes and proteins essential for body function. Proteins are a key building block used in all parts of the body, meaning there can be effects throughout the body that could potentially cause permanent damage or death. Generally, once permanent damage is inflicted, prognosis becomes poor.

The breakdown of proteins associated with clotting in early stages of heatstroke may lead to spontaneous bleeding (haemorrhage) often noticed as blood in the diarrhoea. However, cell toxins can also damage the walls of the veins, activating clotting factors which leads to the formation of spontaneous clots throughout the body. A clot may lead to oxygen deficiency and death of tissues, organs or limbs depending on the location of the clot.

When cells and proteins are broken down, they release particles that are toxic to the cells. These toxins can destroy brain cells leading to permanent neurological dysfunction. They can also damage respiratory cells allowing fluid to accumulate in the lungs and preventing sufficient oxygen transfer.

The toxins released can cause the death of kidney cells, potentially leading to kidney disease and failure. Damage to liver cells could potentially cause ongoing Liver Disease or failure.

The heart and vasculature will respond to increased body temperature by beating faster and dilating blood vessels to attempt to release heat. As temperatures increase, these measures can fail, leading to blood pooling, decreased circulating blood and reduced blood pressure, which reduces oxygen transportation throughout the body. This process can worsen existing heart conditions. Reduced oxygen flow to the heart muscles may also lead to long term arrhythmias (irregular heartbeat rhythm).

Toxins can damage gastrointestinal cells leading to decreased nutrient absorption, intestinal inflammation and allowing bacteria from the digestive tract to enter the bloodstream which could lead to sepsis. Low oxygen due to changes in the lungs and blood can damage the gastrointestinal mucosa, causing it to break away. These may lead to long term digestive upset.

Take Home Messages

Heatstroke is a serious concern in our dogs, especially as the temperatures continue to rise throughout Summer. It is a medical emergency requiring immediate treatment. First aid cooling can be started, but all dogs showing signs of heatstroke will need to see the vet. This rapidly progressing condition could result in permanent health problems or heartbreak. Prevention is essential during the warmer months and in at risk breeds to reduce the risk of it occurring. Learning the signs of heatstroke, first aid treatment and how to prevent it, could save your pet's life!

Further Reading

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Heat Stroke in Dogs - VCA Hospitals
Heat Stroke in Dogs - Animal Emergency Services
Heatstroke in Dogs and Cats - Royal Veterinary College
Heatstroke in Dogs - PetMD
Today's Technichian Heatstroke in Dogs
What You Need to Know About Heatstroke in Dogs