Dogs cool themselves differently than humans. Our bodies produce sweat when we become overheated. This is a very efficient mechanism by which the human body regulates its temperature. Wetness on the skin creates cooling, and evaporation of water draws heat from the skin. Since we have sweat glands all over our bodies, the cooling process takes place over a large surface area of human skin.
Dogs’ Cooling System
When a dog gets excited, stressed, or has recently exercised, its body temperature naturally rises, and it needs to get rid of this extra heat. Unlike humans, dogs have very few sweat glands; most of them are in the animal’s footpads. Dog owners may have noticed that their pets often leave wet footprints behind on hard surfaces. Turns out that this is because the dog is sweating! But the main way dogs regulate their body temperature is by panting with their mouths open.
Panting works in two main ways to cool a dog down: panting evaporates the moisture on the dog’s tongue, and heavy breathing allows moisture to evaporate from the moist lining of their lungs. All this evaporation serves to draw heat from the dog, just as sweat evaporation does for humans.
Dogs have one other mechanism that helps them cool down: the blood vessels in their face and ears can expand. This enables more blood to flow closer to the surface of the skin, allowing heat to be exchanged with the outside environment.
Dogs’ Heating System
If dogs’ paws help cool them down, why don’t they get too cold or freeze in cold weather, especially when walking on snow?
Japanese researchers conducted a study that used electron microscopes to observe dog paws. They found that a dog’s paw is a lot more complicated than our feet. They have veins that are extremely close to arteries. The closeness of the veins and arteries ensures that the heat from the circulatory system goes to the area that is experiencing cooling. When the dog’s paws are on snow or ice, the dog’s heart rate picks up and warm blood is circulated to the paws to counteract the cooling.
The Japanese researchers state that while this system can be found in some other wild animals, the dog is the only domesticated animal that has this trait. This is good news for dogs who can use their paws to cool off in the snow but are protected from frostbite from the same snow.