Dogs differ crucially in their ability to cope with heat. They lose heat mainly by panting and, unlike people, do not sweat profusely. Dogs with snub noses (e.g Pekinese) or dogs with breathing problems are much more prone to heat stress. Long haired dogs are more susceptible than those with short hair.
Signs of overheating
First signs are often increased panting and increased activity with barking or whining. Dogs will look obviously agitated.
The excessive salivation can occur, often with drooling and with strands of saliva hanging from the mouth.
Extreme panting and dark coloured gums will follow. Glassy eyes and stupor may be seen.
Once body temperature is raised to the point that cell death occurs then seizures, coma and death follow.
The key to successful recovery from overheating is early detection and prompt treatment. Remove the animal to a cool shaded place, provide water drink and spray the animal with cool water (cooling may also be achieved by blowing cool air from a fan). Seek imediate veterinary advice if there is not a prompt response to cooling.