Summer, Dogs and Cars Don't Mix
Health Tip: Dogs should never be left in cars on warm days. Parking in the shade, with windows cracked open, is not good enough.
Every year, dogs are injured or suffer a miserable death because their owner left them in a parked car — for “just a minute” — to run a quick errand. Parked cars are deathtraps for pets and children. And, dogs go down very fast!
On a 78-degree day, the temperature inside a parked car can reach 100 to 120 degrees in just a few minutes. On a 90-degree day, the interior temperature can soar to 160 degrees in under 10 minutes.
Dogs can sustain severe brain damage or die from heatstroke in less than 15 minutes. Puppies will expire in half that time. Heat is especially dangerous for dogs because they can only cool themselves by panting and by sweating through their paw pads. Unlike people, they can't sweat through their skin (no pores) to dissipate heat.
The signs of heatstroke symptoms in dogs include restlessness, excessive thirst, thick saliva (frothing), heavy panting, lethargy, lack of appetite, dark tongue, rapid heartbeat, fever, vomiting, bloody diarrhea, and lack of coordination. If a dog in a parked car shows any of these symptoms, call the police or animal control.
We don't recommend you take matters into your own hands and break windows. The owner will eventually return and typically deny their pet was in any danger and blame you for overreacting. That said, if you are action oriented -- OK with us!
Best way to cool the dog is in an air-conditioned vehicle, and then to a veterinarian immediately. If you are unable to transport the dog yourself, take him or her into an air-conditioned building, and provide water to drink.
Depending on the location & situation, spray the dog with a garden hose or immerse the dog in a tub of cool (but not iced) water for up to two minutes at a time in order to lower the body temperature gradually.
You can also place an electric fan in front of the dog. You could also apply cool, wet towels to the groin area, stomach, chest, and paws if possible.
Don't use ice or extremely cold water. You don’t want the dog to be shocked again from too much cold.
Here's a printable mini-poster from he ASPCA that sort of sums it up.