What Is Heatstroke and Why Is It So Dangerous?
Heatstroke occurs when a dog's core body temperature rises above 41°C (106°F) and the body can no longer cool itself effectively. Unlike humans, dogs do not sweat through their skin — they rely almost entirely on panting to regulate their temperature. When the environmental temperature is too high, or when a dog is exercising too hard in warm weather, this system becomes overwhelmed. Without rapid intervention, heatstroke causes organ failure, brain damage, and death — often within 15 to 30 minutes of the temperature reaching dangerous levels.
Across Europe, summers are becoming increasingly intense. Countries such as Spain, Portugal, Italy, Greece, and France regularly record temperatures above 38°C, and even the UK and northern Europe are experiencing more frequent heatwaves. Every summer, hundreds of dogs across the continent die from heatstroke — the vast majority of cases are preventable.
Which Dogs Are at Highest Risk?
While any dog can suffer heatstroke, certain breeds and types are particularly vulnerable.
Brachycephalic Breeds
Dogs with flat faces — including French Bulldogs, English Bulldogs, Pugs, Boxers, Shih Tzus, and Boston Terriers — have narrowed airways that make panting far less effective. They overheat far more quickly than other breeds and should be treated with extreme caution in warm weather. Even moderate temperatures can be dangerous for these dogs if they are exercising or stressed.
Thick-Coated and Large Breeds
Dogs with dense double coats, such as Huskies, Samoyeds, Chow Chows, and Saint Bernards, are designed for cold climates and struggle in the heat. Large and giant breeds — Great Danes, Labrador Retrievers, and German Shepherds — also have a higher surface-area-to-mass ratio that makes it harder to shed heat.
Other High-Risk Factors
- Old age or very young puppies
- Dogs that are overweight or obese
- Dogs with heart or respiratory disease
- Dogs not acclimatised to hot weather
- Dogs left in cars, conservatories, or poorly ventilated spaces
On a 22°C day, the temperature inside a parked car can reach 47°C within an hour. This is not an exaggeration — studies consistently confirm these figures, and dogs left in cars account for a significant proportion of heatstroke deaths each summer across Europe.
Recognising the Signs of Heatstroke
Early Warning Signs
- Excessive, heavy panting that seems out of proportion to activity
- Thick, ropy saliva
- Restlessness or agitation
- Bright red gums and tongue
- Seeking shade or lying down suddenly during exercise
Signs of Severe Heatstroke — Act Immediately
- Gums turning pale, grey, or blue (a sign of circulatory failure)
- Vomiting or diarrhoea, sometimes with blood
- Loss of coordination, stumbling, or inability to stand
- Glazed, unfocused eyes
- Seizures or muscle tremors
- Loss of consciousness or collapse
If you observe any of the severe signs above, call your vet immediately. Do not wait to see if your dog improves — heatstroke is fatal without treatment and every minute counts.
Step-by-Step First Aid for Heatstroke
The goal of first aid is to begin cooling your dog while getting them to a vet as quickly as possible. Do not delay the vet trip in order to cool your dog at home — cooling and transport should happen simultaneously.
- Move your dog to a cool, shaded area immediately. If indoors, use air conditioning or a fan.
- Pour cool — not cold, not iced — water over your dog's body. Focus on the neck, armpits, groin, and paws, where blood vessels are close to the surface. Tap water at room temperature is ideal.
- Allow your dog to drink small amounts of cool water if they are conscious and able to swallow. Do not force water into their mouth.
- Place wet towels over your dog, but do not wrap them tightly — this traps heat. Re-wet the towels frequently.
- If you have a fan, direct it towards your dog to assist evaporative cooling.
- Call your vet immediately and tell them you are on the way with a dog showing signs of heatstroke. They can prepare for your arrival.
- Keep the car windows open or air conditioning on during transport.
What NOT to Do
- Do NOT use ice or ice-cold water. This causes blood vessels near the skin to constrict, which actually traps heat inside the body and worsens the condition. It can also cause shock.
- Do NOT submerge your dog in cold water or place them in a freezing bath.
- Do NOT cover your dog with wet towels without keeping them cool and wet — a warm damp towel acts like a greenhouse.
- Do NOT delay getting to the vet to continue cooling at home.
- Do NOT assume your dog has recovered because they seem better — internal organ damage may not be apparent and requires veterinary assessment.
Veterinary Treatment
At the clinic, your vet will monitor your dog's core temperature, provide intravenous fluids, and assess for complications including kidney failure, abnormal blood clotting, and brain swelling. Even dogs that appear to recover quickly need monitoring for at least 24 hours. Your vet will guide you on follow-up care.
In Europe, emergency veterinary services are available in all major cities. If your usual vet is unavailable, search for the nearest emergency animal hospital — in Spain (clínica veterinaria de urgencias), in France (clinique vétérinaire d'urgence), or in Italy (clinica veterinaria d'urgenza). Save the number of your nearest emergency clinic before the summer season arrives.
Prevention: The Best Treatment of All
Walk your dog during the coolest parts of the day — early morning and evening. Always carry water on walks. Never leave your dog unattended in a car, even with the windows cracked. Provide shade and fresh water at all times when your dog is outdoors. On very hot days, keep exercise to a minimum and let your dog rest indoors.