As dogs can only sweat through their legs and nose, they don't expel their internal heat and express their discomfort panting. Normally, more they pant, more hot they are and more sick they feel. The main symptoms of a heat stroke are: high rectal temperature, dark red gums, panting, dry mouth and throat and dense saliva. Your dog may feel lethargic, suffer dizziness and vertigo, be unable to stand or get up. They may also faint and lose consciousness. Should these symptoms appear, it is important to act quickly. Take the dog out of the sun, possibly in a cool and breezy place. Dampen your dog's coat with fresh water and wet cloths, avoiding excessively cold water. Give them water to drink, but don't force them, then go to the vet.