Why Do Dogs Pant?
Jessie's, um, weight issues might mean he heats up more easily. But like all dogs, he pants for the same reason people perspire: to cool off.
Water absorbs heat, so when water in the form of sweat evaporates off our skin, it carries away excess body heat. It may not always be pretty, but it's effective. Since dogs are covered in fur and have very few sweat glands (only in the pads of their paws), perspiring isn't an option for Jessie and his canine cohorts. "Panting allows a dog to move air over the moist tissues of his mouth and tongue," says Jennifer Lander, director of veterinary medicine at the ASPCA. "This helps evaporate extra moisture and cools him off."
The breath dogs expel through their mouths when panting is about 10 degrees warmer than air exhaled during normal nose-breathing, evidence that a lot of body heat is being released.
A dog's tongue can even get bigger when he pants, increasing in surface area so more heat is released faster. Panting isn't as efficient as sweating, but at least dogs never have to worry about deodorant failure.
Explain It to Your Kids
Have your child run one hand under a faucet, then hold both hands in front of a fan. The wet one feels cooler because the moisture helps heat escape. When Jessie pants, his wet tongue releases heat just like your wet hand. A cooler tongue and mouth help cool the blood circulating through his body, allowing him to chill out all over.