Do dogs lack sweat glands?
Lots of people know that dogs cool down by panting, not sweating. But that doesn’t mean that dogs don’t sweat nor does it mean that they lack sweat glands.
As it happens they both have the glands and make use of them. I don’t even need to get all pedantic and insist that things like tears, milk and scent are produced by modified sweat glands. Dogs have the same kinds of sweat glands humans do, they just use them differently.
There are two different kinds of sweat glands. Epitrichial (or apocrine) glands are ducted into hair follicles. Atrichial (or eccrine) glands are ducted directly to the surface of the skin. We have both kinds. In humans the epitrichial ones are vestigial, though they are largely responsible for the kind of sweat that leads to body odour, and thus have spawned an entire industry to keep it at bay. It’s the atrichial ones that we really think of as sweat glands — they are the ones hooked up to the nervous system and which start secreting when we get too hot.
Sweat carries away excess heat by evaporating off the skin but as every dog lover will attest dogs don’t sweat to cool down. Instead they pant which relies on the same principle of evaporation but from the mouth instead of the skin.
Dogs also have both kinds of sweat glands, though, and they use them for other things. Most of a dog’s body is covered with epitrichial glands which are of importance for maintaining healthy skin. Atrichial glands, the ones that are so important to us, are only really found on the few bare parts of a dog’s body, like the pads of the feet. The moisture they produce helps improve grip.
To us sweating is so much about cooling down that it’s easy to imagine it serves no other purpose. Really though, sweat glands have many roles throughout the animal kingdom. For us sweat is about regulating temperature, for dogs it is about not slipping over. And though it isn’t really sweating as we know it, dogs do sweat.