Heatstroke in dogs and cats
Heatstroke happens when the animal cannot regulate its temperature and it rises to dangerous levels. Dogs and cats don't sweat like us: they cool down mainly by panting, a mechanism that is quickly overwhelmed by heat and humidity. It is a life-threatening emergency that can damage organs within minutes.
Why it is so serious
When body temperature rises above certain limits, proteins and organs begin to fail: kidneys, liver, blood clotting and the nervous system. That is why untreated heatstroke can be fatal even if the animal at first only seems "tired". A dog or cat's normal temperature is around 38–39 ºC.
| Temperature | Situation | What to do |
|---|---|---|
| 38–39.2 ºC | Normal | No alarm |
| 39.3–40 ºC | Raised | Watch, cool down, avoid effort |
| 40–41 ºC | Heatstroke | Cool and go to the vet now |
| above 41 ºC | Critical | Life-threatening: cool on the way to the clinic |
Risk situations
- Leaving the animal in a car, even "just for a moment": the inside heats up very fast.
- Exercise or walks during the hottest hours.
- Flat-faced (brachycephalic) breeds — bulldog, pug, boxer, Persian — which breathe less efficiently.
- Older animals, puppies, overweight pets or those with heart or breathing problems.
- Lack of shade and water, or high humidity.
Symptoms by severity
| Level | Signs |
|---|---|
| Mild | Heavy panting, thick drooling, restlessness, seeking shade |
| Moderate | Very red gums, weakness, staggering, vomiting or diarrhoea |
| Severe | Disorientation, pale or bluish gums, collapse, seizures, loss of consciousness |
What to do step by step
- Move it out of the heat to a cool, ventilated, shaded place.
- Cool it with lukewarm water (never icy) on paws, groin, armpits and belly. Very cold water constricts the vessels and makes it harder to lower the temperature.
- Move the air with a fan or by fanning it: it helps evaporation and cooling.
- Offer fresh water if it is conscious, without forcing it to drink.
- Call a vet and go immediately, even if it seems to improve: there may be internal damage.
- Stop actively cooling once it is clearly more alert, to avoid hypothermia; the vet will continue monitoring.
What NOT to do
- Don't use ice or icy water: they worsen cooling.
- Don't cover it with wet towels that trap heat.
- Don't force it to drink or give anything by mouth if it is unconscious or having seizures.
- Don't wait for it to "recover on its own".
What the vet will do
At the clinic they will lower the temperature safely and assess organ damage. Treatment may include fluid therapy (intravenous fluids), oxygen, monitoring of clotting and of kidney and liver function, and supportive medication. Monitoring over the following hours is key, because some complications appear later.
How to prevent it
- Never leave the animal in the car, not even with the windows cracked open.
- Walk early and late in the day in summer; avoid hot tarmac.
- Make sure shade and fresh water are always available.
- Take extra care with flat-faced, older or overweight pets.
Frequently asked questions
Why lukewarm water and not cold?
Very cold water constricts the skin's blood vessels and makes it harder for the body to release heat, and it can cause a sudden drop. Lukewarm water, together with moving air, cools more effectively and safely.
If it recovers, do I still need the vet?
Yes. Heatstroke can cause organ damage that isn't visible from outside and complications that appear hours later. Always go for a check-up, even if the animal seems fine.
At what temperature does it become dangerous?
The normal temperature of dogs and cats is around 38–39 ºC. From 40 ºC we talk about heatstroke, and above 41 ºC the situation is critical. If you can measure it safely, it is useful information for the vet.
Do cats get heatstroke too?
Yes, although it is less common because they tend to seek cool spots. Flat-faced cats (such as the Persian) and older cats are more vulnerable.
How quickly can heatstroke happen inside a car?
Very quickly: on a hot day the inside of a car can reach dangerous temperatures within minutes, even in the shade or with the windows cracked.
Can I give it something to bring the fever down?
No. It is not a fever but excess heat, and human fever medicines are toxic to dogs and cats. Cool it with lukewarm water and go to the vet.
This is first-aid guidance only and does not replace a vet's diagnosis. In any emergency, contact a professional.
