The dog days of summer are upon us, at least in this neck of the woods. I won't run a dog during these spells of heat unless it's in the coolness of the morning, with plenty of water carried, and close to a water supply where the dog can immerse the entire body to cool off.
It's a dangerous time for dogs, as their cooling system is far less refined than that of a human. The main way for a dog's body to lose excess heat is through panting, and in the folds of the nose. Another method is through the paws.. Give the dog the ability to cool the paws, and the body will remain cool.
Dogs do not lose heat through the skin as humans do. The fur is an insulator, and tests have shown no difference in heat loss whether the coat is clipped, or kept long. human's feel it helps because of our own adaptations.
But, as I mentioned, the main source of cooling is provided by the open mouth during panting, and the perspiration and high surface area of the folds in the nose. Alot of air is taken in and out during respiration, and this surface are acts like the radiator of an automobile.
Even at home, I feel it's important for the dogs to have a place to cool off whenever they'd like. A stock tank, small pool used to build backyard ponds, even a small childs wading pool is enough to all one's dogs to weather the hot extremes easily. My dog's always have at least a 12' depth of water to jump into.. and don't forget to change the water every few days to prevent providing a place for mosquitos to breed..
Field trials are suspended for the summer, and with good reason for the dog's protection. We can still exercise our dogs though, if we are thoughtful about it and use some common sense.. Head for the water, where you and the dogs can stay cool!
For some good information on heat adaptation in canines, click here and here