Every summer, animals die shut in cars — sometimes for ‘just a few minutes’. In hot weather the cabin turns into an oven: the temperature climbs far faster than you would think, and a dog, which cannot sweat as we do, is overwhelmed within minutes. Here is why, how to recognise heatstroke, and above all how to prevent it.
Why a car becomes a trap
A car in the sun behaves like a greenhouse: the windows let light in, which heats the seats and the cabin, but the heat can no longer escape. Even on a day that feels mild to you, the temperature inside can pass 50 °C. Opening the windows a crack makes almost no difference: it is not air that runs short, it is heat that builds up.
Dogs are especially vulnerable. Unlike us, they barely sweat at all: they cool themselves mainly by panting. Once the air itself is scorching, that system fails, their body temperature spirals and the organs begin to suffer. This is heatstroke (hyperthermia) — an emergency that can kill in under an hour. Cats and exotic pets are every bit as much at risk.
How many degrees, how quickly?
The measurements leave no room for doubt: in a closed car, the temperature inside rises by close to +20 °C in half an hour on average — whatever the weather outside. Run the estimate yourself:
Estimate based on the reference measurements of temperature rise inside vehicles (Null & McLaren, Pediatrics 2005): the rise depends mostly on time, hardly at all on the starting temperature — and opening the windows a crack barely reduces it.
Recognising heatstroke
These signs should alarm you immediately:
- Heavy, noisy panting that does not settle
- Profuse drooling, thick saliva
- Very red gums and tongue (later, more seriously, bluish or pale)
- Restlessness, then quite the opposite: lethargy and a staggering gait
- Vomiting or diarrhoea
- In severe cases: collapse, seizures, loss of consciousness
What to do, right away
- Move the animal out of the heat and into a shaded, airy spot.
- Cool it down gradually with cool water — not ice-cold: wet the belly, the inside of the thighs, the neck and the legs. Ice-cold water tightens the blood vessels and, paradoxically, slows the cooling down.
- Offer small amounts of cool water to drink if it is conscious, without ever forcing it.
- Drive it to the vet immediately, with the car well ventilated, phoning the practice to say you are on your way.
Do not give any medicine on your own initiative, and do not wait to see whether ‘it passes’.
What if you see an animal shut in a car?
Assess its condition first: if it is panting violently, drooling, looks flat or is convulsing, this is an emergency. Look quickly for the owner (nearby shops, an announcement at the car park) and, where the danger is obvious, call the police on 117, who are authorised to intervene. In Switzerland, leaving an animal to suffer can fall under the Animal Welfare Act (LPA). Breaking a window yourself should only ever be a very last resort and carries legal risks: calling the authorities is the safer route.
Prevention is better than cure
- In hot weather, leave your pet at home, somewhere cool.
- Avoid car journeys and walks during the hottest hours.
- Always carry water and plan breaks in the shade.
- Mind scorching tarmac, which can burn paw pads.
- Be extra vigilant with at-risk animals: flat-faced dogs (bulldogs, pugs…), overweight or elderly animals, heart patients and thick-coated breeds.
The key points: a car in the sun becomes deadly within minutes, heatstroke is a veterinary emergency, and the only real protection is never to leave your pet inside.