Why Heatstroke Is a Medical Emergency
Dogs cannot sweat through their skin the way humans do. They regulate body temperature almost entirely through panting, which becomes rapidly ineffective when the surrounding air is hot and humid. When a dog's core body temperature rises above 41°C (106°F), heatstroke sets in. Above 43°C (109°F), the condition is frequently fatal. During summer months, heatstroke is one of the most common warm-weather emergencies seen by veterinary clinics worldwide, from southern Europe to North America, Australia, and beyond.
Understanding the signs, knowing what to do in the first minutes, and taking preventive steps can be the difference between a full recovery and a tragedy. While dogs are most commonly affected, cats are also susceptible to heatstroke, particularly those kept in poorly ventilated spaces or left outdoors during peak heat hours.
Warning Signs of Heatstroke in Dogs
Heatstroke develops quickly, often within minutes of exposure to extreme heat. The earlier you recognise it, the better the outcome. Watch for the following:
Early Signs
- Rapid, heavy panting (300 to 400 breaths per minute in severe cases)
- Excessive drooling, often thick and stringy
- Restlessness or agitation
- Bright red gums and tongue
- Increased heart rate
Advanced Signs
- Vomiting or diarrhoea, sometimes with blood
- Glazed or unfocused eyes
- Weakness, stumbling, or difficulty standing
- Muscle tremors or seizures
- Loss of consciousness
Brachycephalic breeds (French Bulldogs, Pugs, Bulldogs) and dogs with thick double coats are at significantly higher risk and can deteriorate faster than other breeds. Senior dogs, puppies, and overweight dogs are also more vulnerable.
What to Do Immediately: First Aid for Heatstroke
If you suspect your dog has heatstroke, act within minutes. Do not wait to see if they improve on their own.
- Move them to a cool area. Get your dog out of direct sun immediately. A shaded outdoor area or an air-conditioned room is ideal.
- Apply cool (not cold) water. Wet your dog's body with cool water, focusing on the neck, armpits, groin, and paw pads. Do not use ice or ice-cold water, as rapid cooling can cause blood vessels to constrict, trapping heat inside the body and making the situation worse.
- Use a fan if available. Airflow accelerates evaporative cooling. A fan combined with cool water is significantly more effective than water alone.
- Offer small amounts of cool water to drink. Do not force water if your dog is unable to swallow or is unconscious.
- Get to a vet immediately. Even if your dog appears to recover, internal organ damage can occur without visible symptoms. A veterinary assessment is essential after any suspected heatstroke episode.
Search for your nearest emergency veterinary clinic in advance so you are not scrambling in a crisis. Many cities worldwide now have 24-hour emergency animal hospitals. It is worth saving the number in your phone before you need it.
What NOT to Do: Common Mistakes That Make Things Worse
In a panic, well-meaning owners sometimes take actions that inadvertently worsen their dog's condition. Avoid the following:
- Do not use ice or ice-cold water. Extreme cold causes peripheral blood vessels to constrict, which traps heat in the body's core and can accelerate organ damage. Cool tap water is the correct choice.
- Do not force water into an unconscious or semi-conscious dog. A dog that cannot swallow properly is at serious risk of inhaling water into the lungs (aspiration), which can cause a secondary, life-threatening complication.
- Do not leave your dog in a cool car and assume they are safe. Even with windows cracked, a parked car heats up rapidly. The only safe option is to remain with your dog in a genuinely cool environment.
- Do not over-cool. Once your dog's breathing begins to normalise and they become more alert, stop active cooling. Bringing their temperature down too far too quickly can cause hypothermia, which carries its own serious risks.
- Do not skip the vet. Even if your dog appears to make a full recovery at home, internal organ damage (particularly to the kidneys and liver) can develop silently over the following 24 to 72 hours. A veterinary check is not optional after a heatstroke episode.
When to Call the Vet Immediately
Home first aid buys time. It does not replace veterinary care. Call your vet or head to an emergency clinic without delay if your dog shows any of the following:
- Loss of consciousness or collapse
- Seizures or uncontrolled muscle tremors
- Vomiting or diarrhoea with blood
- Gums that are pale, white, blue, or grey rather than pink or red
- No improvement within 10 minutes of beginning first aid
- Rectal temperature above 41°C / 106°F (if you have a thermometer available)
- Any dog from a high-risk group (brachycephalic, elderly, puppy, obese) showing even mild symptoms
When in doubt, call. A brief phone consultation with your vet takes two minutes and could save your dog's life.
How to Prevent Heatstroke
Prevention is straightforward once you understand the conditions that cause heatstroke. The following measures significantly reduce risk during warm weather, wherever you are in the world.
Adjust Walk Times
Walk your dog in the early morning or evening, avoiding the hottest part of the day. In many regions during summer, this means before 9am or after 7pm. Asphalt and paving surfaces can reach 52°C (126°F) at an ambient temperature of 25°C (77°F), and up to 60°C (140°F) at 30°C (86°F). At those temperatures, paw pads can burn in under 60 seconds. If you cannot hold the back of your hand on the pavement for 7 seconds, it is too hot for your dog's paws.
Provide Constant Access to Water
Dogs need approximately 50 to 60ml of water per kilogram of body weight per day, and significantly more in hot weather or after exercise. Always carry water on walks. A portable travel bottle with an integrated bowl makes hydration on the go effortless, with no need for a separate dish.
Use a Cooling Vest
A quality cooling vest can reduce your dog's skin surface temperature by 3 to 5°C (5 to 9°F), which meaningfully reduces the effort required to maintain a safe core temperature. Our Dog Cooling Vest is designed for breathability and comfort during outdoor activity in warm weather, and is available in sizes from S to XXXL to suit all breeds.
Never Leave a Dog in a Parked Car
On a 20°C (68°F) day, the interior of a parked car reaches 40°C (104°F) within 30 minutes and 47°C (117°F) within an hour. On a 30°C (86°F) day, those temperatures are reached in half the time. In many countries, leaving a dog in a parked car in dangerous heat is a criminal offence under animal welfare legislation. Even where it is not explicitly illegal, it constitutes a serious failure of duty of care.
Create a Cool Environment at Home
Ensure your dog has access to a cool, shaded space indoors. Tiled floors are naturally cooler than carpet. Cooling mats, fans, and air conditioning all help. Avoid leaving dogs in conservatories, cars, or enclosed outdoor spaces without shade and ventilation.
High-Risk Situations to Avoid
- Beach or park visits during peak sun hours without shade and water access
- Intense exercise or play sessions during the hottest part of the day
- Muzzles that restrict panting (use only when necessary and for short periods)
- Leaving dogs in gardens or yards without shade or water
- Travelling in a car without air conditioning or adequate ventilation
Breeds at Highest Risk
While all dogs are susceptible to heatstroke, the following breeds require extra vigilance in hot weather:
- Brachycephalic breeds: French Bulldog, English Bulldog, Pug, Shih Tzu, Boxer (restricted airways make panting less effective)
- Heavy-coated breeds: Husky, Malamute, Chow Chow, Saint Bernard (thick coats trap heat)
- Working and high-energy breeds: Border Collie, Labrador, Springer Spaniel (may not self-regulate activity in heat)
For a broader look at keeping your dog comfortable and safe throughout the summer season, see our guide on How to Keep Dogs Cool in Summer.
Frequently Asked Questions
What temperature is dangerous for dogs?
A dog's normal body temperature is between 38°C and 39.2°C (100.4°F to 102.5°F). Heatstroke begins at 41°C (106°F) and becomes life-threatening above 43°C (109°F). Ambient temperatures above 25°C (77°F) combined with humidity and direct sun exposure can push a dog toward heatstroke faster than most owners expect.
How quickly can heatstroke kill a dog?
In severe cases, heatstroke can cause irreversible organ damage within 15 to 30 minutes of onset. This is why immediate first aid and emergency veterinary care are critical. Do not wait to see if your dog recovers on their own.
Can a dog recover fully from heatstroke?
Dogs that receive prompt first aid and veterinary treatment often make a full recovery. However, severe cases can result in lasting kidney, liver, or neurological damage. Early intervention is the single most important factor in outcome.
Is it safe to shave my dog in summer?
For most double-coated breeds, shaving is not recommended. The undercoat provides insulation against both heat and cold, and shaving can disrupt the coat's natural thermoregulation. Consult your vet or a professional groomer before making this decision for your specific breed.
Can cats get heatstroke too?
Yes. Cats are also vulnerable to heatstroke, particularly those kept in poorly ventilated rooms, conservatories, or outdoor enclosures without shade. Signs in cats include rapid breathing, drooling, lethargy, and stumbling. The same first aid principles apply: move to a cool area, apply cool water, and seek veterinary care promptly.