Contact your veterinarian.
Every dog is a potential victim of summer's heat.
One of the most common causes of heat stroke is leaving an animal in a hot car. Leaving a window cracked doesn't prevent heat build-up. Fortney says leaving a dog in a car on a warm day is risking the dog's life. Dogs don't sweat, and they don't have an efficient way to cool themselves down. If they are panting, it may be because they need the oxygen because they've been exercising, or it may mean they are trying to get rid of built-up heat in their bodies.