How to cool down a dog with heatstroke: do this first
The core principle, from the Royal Veterinary College's canine heatstroke research group, is "cool first, transport second." Call the vet immediately by all means-but don't leave your dog hot while you drive.
- Move your dog out of the heat-shade, indoors, or a well-ventilated area-and stop whatever activity generated the heat.
- Get water on them. For a young, healthy dog, cold-water immersion is the recommended and most effective method. For an older dog, a puppy, or a dog with underlying health problems, pour on any available water that is cooler than the dog and combine it with air movement (a fan, a breeze, air conditioning)-this is called evaporative cooling. On thick-coated dogs, work water down to the skin at the neck, belly, groin, and legs rather than just wetting the top coat.
- Keep air moving over the wet coat. Water plus airflow cools substantially better than water alone.
- Offer small amounts of drinking water if your dog is alert and swallowing normally. Never force water into a dog who is not fully conscious-that risks aspiration.
- Cool the car down before you load them in, so transport doesn't undo the cooling you just did.
- Transport once cooling is underway, continuing to cool en route if you have someone to help.
About cold water: the advice has changed
Older first-aid guidance-still repeated widely-warns against cold or ice water on the theory that it causes surface blood vessels to constrict, trapping heat in the core. Research has disproven this. The RVC's heatstroke research group addresses this myth directly, stating that cold-water immersion is the recommended cooling method for young, healthy dogs and citing work in which conscious dogs with heat-related illness cooled faster in 1-16°C water than in 18-25°C water. Human and equine sports-medicine research reached the same conclusion. If you have been told to use only tepid water, that guidance is out of date.
The practical exception is not about temperature but about the dog: full immersion isn't the right choice for an older or unwell dog, or one who is collapsed or not fully conscious-there, water plus air movement is the recommended approach.
When to stop cooling
Over-cooling is a real risk once the emergency cooling is working. Current advice is to stop active cooling once the dog's temperature drops below 40°C (104°F); many veterinary texts set the stopping point at 39.5°C (103°F). For reference, a normal canine temperature is roughly 38.3-39.2°C (101-102.5°F), and dogs above about 41°C (105.8°F) are likely in heatstroke territory. If you don't have a thermometer, cool on the way to the vet and let the clinic take over-don't delay transport to keep cooling indefinitely.
Recognizing heatstroke
Heatstroke is classed as a medical emergency by veterinary sources including Cornell University's Riney Canine Health Center and the AKC, because of the organ damage sustained hyperthermia causes.
Early signs, worth acting on before they progress:
- Heavy, rapid panting that doesn't ease with rest or shade
- Bright red or dark red gums (normal gum color is pale pink)
- Excessive drooling
- Restlessness or apparent distress
Signs of progression toward a true emergency:
- Weakness, wobbliness, or difficulty standing
- Vomiting or diarrhea
- Collapse
- Seizures
- Gums turning pale, gray, or blue (a sign of shock)
Any of the later-stage signs need emergency veterinary care immediately-and even early signs in a dog that's been in a hot environment are worth acting on right away rather than waiting to see if they worsen.
Why catching it early matters this much
Severity at the point of veterinary presentation is strongly tied to outcome. In a large UK study of primary-care veterinary records covering 945,543 dogs, 97% of dogs treated for mild heat-related illness survived, compared with 43% of dogs treated for severe heat-related illness. Dogs presenting with severe heat-related illness had roughly 65 times the odds of death compared with dogs presenting with mild illness.
The same body of research found that fewer than a quarter of dogs presented to UK vets with heat-related illness had been actively cooled before transport. That gap-between what owners do instinctively (drive) and what the evidence supports (cool, then drive)-is the single most changeable factor in this entire guide.
Who's at higher risk
- Brachycephalic (flat-faced) breeds-Bulldogs, Pugs, Boston Terriers, and similar breeds pant less efficiently due to airway structure, and are disproportionately represented in heatstroke cases
- Heavy or thick-coated breeds, which retain heat more than short-coated dogs
- Overweight dogs-excess body fat insulates and makes cooling less efficient
- Senior dogs and very young puppies, whose temperature regulation is less robust
- Dogs with underlying heart, respiratory, or other chronic conditions
- Dogs not acclimated to heat-a dog used to a cooler climate or mostly indoor life is at higher risk during a sudden hot spell or travel to a hotter region
If your dog fits more than one of these categories, treat the prevention section below as more important, not optional.
One specific safety note: never muzzle a dog who is overheating or showing heatstroke signs. Panting is a dog's primary cooling mechanism, and a muzzle restricts it-see muzzle training for dogs for the same warning in the context of fitting and using a muzzle generally.
Prevention
- Never leave a dog in a parked car, even briefly, even with windows cracked-car interiors heat dramatically faster than outside air temperature, and this remains one of the most common preventable causes of heatstroke
- Adjust exercise timing and intensity on hot or humid days-early morning or evening walks, shorter distances, and attention to your specific dog's tolerance
- Always provide shade and fresh water during outdoor time
- Check pavement temperature, not just air temperature-if it's too hot for your bare hand held on the pavement for five seconds, it's too hot for your dog's paws
- Be more cautious with high-risk dogs-what's safe heat/exercise exposure for a fit, average dog may not be safe for a brachycephalic, overweight, senior, or already-unwell dog
FAQ
Is heatstroke the same as just being hot and tired after exercise?
No-normal post-exercise panting eases with rest, shade, and water within a reasonable time. Heatstroke signs (very heavy panting that doesn't ease, bright red gums, weakness, vomiting) indicate the body's cooling mechanisms are being overwhelmed, which is more serious than ordinary exertion.
My dog seems fine now after a scare in the heat-do I still need a vet?
Yes, if they showed any moderate-to-severe signs (not just brief heavy panting that resolved quickly with shade and water). Heatstroke can cause internal organ damage that isn't visible from the outside and can worsen hours later even if your dog seems to be recovering.
Can heatstroke happen indoors?
Yes, though less commonly-a poorly ventilated room, a broken air conditioner during a heat wave, or an unventilated space can still raise a dog's body temperature dangerously, particularly for high-risk dogs.
How quickly can heatstroke become fatal?
It can progress to organ damage and death within hours if untreated, sometimes faster in severe cases-which is why immediate action (cooling plus an emergency vet call) matters more here than in almost any other situation.
Should I towel-dry my dog after cooling them with water?
No-leave them wet, since the evaporating water is actively helping cool your dog on the way to the vet. Dry them off only once they're stable and a vet has confirmed it's appropriate.
Is draping a wet towel over my dog a good way to cool them?
It's a weak substitute for the methods above. A towel left in place warms to the dog's temperature and then acts more like insulation than a coolant. Current guidance is to apply water directly and keep air moving over the coat, rather than covering the dog and leaving it-if you only have a towel, keep re-wetting it with cool water rather than leaving it draped.
What if my dog collapses in the heat and won't drink?
Don't attempt to give water by mouth to a dog who isn't fully conscious or is unable to swallow-that risks aspiration. Cool them with water and air movement, get the car cool, and transport immediately while calling ahead.