How Dogs Regulate Their Temperature
Dogs do sweat, but not like humans. Dogs have two types of
sweat glands. One type, called merocrine glands, are in their footpads. They sweat through their footpads. They
also have some sweat glands in their nose. Although they help keep the dog cool, very little of their body heat is
lost through their footpads. The other type of sweat gland is called apocrine glands, which are over most of their
body, but are not to keep the dog cool. Their purpose is to release pheromones, which, to put it simply, makes a
dog smell like a dog.
The main cooling function for dogs
is panting. The Air is drawn in through their nose. There are folds in the nose that increase the surface area for
moisture in the nose to evaporate from, cooling the nose. The air is exhaled through the mouth. The moisture in the
air is absorbed and the heated air leaves the dog. Along with this, since the dog's mouth is open with it's tongue
hanging out, the saliva on the dog's tongue evaporates cooling the tongue which has a rich blood supply, and so
cools the blood which has transported heat from inside the dog's body.
Another temperature controlling
organ is the spleen. The spleen stores blood, and when the dog gets hot, the spleen releases additional blood into
the blood stream to help carry heat to the surface. Relative to body size, dogs have larger spleens than humans.
The greater release of blood from the spleen when dogs exercise may be one reason why dogs usually have a higher
endurance level than most people.
One other interesting
physiological aspect of the dog's body is that a complex of small veins and arteries at the base of the dog's neck
can thermally isolate the dog's head from the rest of the dog's body, where the muscles generate heat is during
exercise. This protects the dog's brain, which is the most temperature-sensitive organ in the dog's body. Compared
to other animals, the dogs can endure high exertion in a hot environment significantly longer
than animals that don't have this feature. A dog chasing a rabbit in a hot environment may not be able to initially
catch the rabbit, but can keep chasing the rabbit until the rabbit slows down from overheating.
For information on dog's health,
go to: Health