An RSPCA worker deliberately locked himself inside a car for 25 minutes to demonstrate the deadly conditions dogs experience when left in hot vehicles. The experiment, conducted outside the charity's Cardiff office, saw temperatures inside the vehicle soar to a staggering 57.1°C.
Experiment Details
Chris O'Brien, from RSPCA Cymru, armed himself with a digital thermometer and stopwatch to document the rapid temperature rise and its physical effects. Starting at 23.3°C, the temperature inside the car rocketed to 35.1°C within just five minutes. By the 10-minute mark, it had climbed to 43.6°C, with O'Brien reporting a faster heartbeat and heavier breathing.
“I am baking. It is so, so hot in here. I can't even begin to tell you,” O'Brien said. “Obviously I'm sweating a lot. Dogs regulate their body temperature very differently to humans, so they would struggle even more in these conditions.”
Rapid Temperature Rise
After 15 minutes, the temperature reached 48.8°C, passing 50°C just two minutes later. “Everything in the car is absolutely boiling,” O'Brien noted. “I cannot imagine how a dog would feel.” By the end of the 25-minute challenge, the thermometer read 57.1°C.
O'Brien emphasized that while he knew he could leave the car at any time, a dog would not understand that, leading to increased distress and danger. He added: “I cannot believe the impact this has had in such a short space of time. This is so dangerous. Never leave a dog in a hot car.”
Heatstroke Warning
The warning comes as forecasters predict another spell of hot weather across parts of the UK, with temperatures expected to climb into the 30s°C. The RSPCA reminds owners that leaving a dog in a parked car—even for a few minutes or with windows slightly open—can quickly become fatal. Dogs cannot cool themselves as effectively as humans, making them far more vulnerable to heatstroke.
If you spot a dog showing signs of distress in a hot car, the RSPCA advises calling 999 immediately, as the situation can become life-threatening in minutes.
