Always check the dog's feet after a run for cuts and rawness. A dog can sweat through his feet pads, anus and tongue. He does not have the heat releasing mechanisms of many other animals. Dogs are susceptible to heatstroke and other related problems. Dogs that were bred for cold climates such as Huskies, Akita's have been transplanted by people to warm climates this is not natural and one can expect behavioural and health problems.
Dogs react to heat by panting or digging holes in the earth under shady trees or bushes.
Locking dogs in closed cars can be fatal because a car heats and and so do dogs. Exercise raises your dog's metabolism and boosts his temperature, which in turn can turn to heatstroke. For obese dogs the problem is worse. Never exercise a dog in the heat of the day and keep his weight under control. It also a good idea to give your dog his water dish to enable him to drink before a walk.