Heat Exhaustion
Some breeds of dog are more prone to heat exhaustion than others - Chow Chows and Bulldogs come to mind, but several other short-nosed breeds can also be affected.
The most common reason for heat exhaustion is human error. Dogs are too often left inside cars in summer without adequate ventilation.
The owner is usually just thoughtless, or caught out by a change in the weather during a longer than expected shopping trip. The temperature inside a closed car in summer in even a temperate climate can kill a dog.
Many have died in this way. The signs of heat stress are obvious distress, heavy panting, and an inability to breathe deeply enough indicated by a half strangled noise coming from the dog's throat. The dog's tongue looks swollen and blue.
Treat as an immediate emergency, and do not attempt to take the clog for veterinary treatment until you have started its resuscitation.
Plenty of cold water is the first-aid treatment. Ideally, immerse the whole dog in a bath - use a cattle trough if there is one nearby.
Bathe the dog all over with cold water, but especially drench its head; and keep doing it until the dog shows signs of easier breathing. Then take it to the veterinary surgeon.
The vet will possibly put the dog on to an oxygen air flow, and will probably give it an injection to reduce the swelling in its throat, but unless the vet happens to be at hand, as he may be at a dog show, the life-saving treatment will have been given before the dog gets to the surgery.