The cells of the dermis provide a framework for blood vessels to bring oxygen and nutrients to the skin and nerves to help the dog react to and interact with his world. Blood vessels in the dermis help control Fido's body temperature. When he runs and romps and builds up body heat, the blood flow to Fido's skin increases to release the heat to the environment. In cold weather, blood flow to the skin dwindles to keep the heat where it does the most good. Under the dermis is the subcutaneous fatty layer that has two widely disparate jobs as protective shock absorber and food storage locker for certain vitamins and energy bits called lipids.
Hair follicles rise from the dermis layer.
The dog's dermal skin layer has two types of glands that produce fluids. The apocrine glands, which produce sweat in humans, have two other functions in dogs - they help seal the outer layer of the epidermis and they secret pheromones that give dogs a distinctive body odor. The eccrine glands in the pads of the paws do produce a watery secretion similar human perspiration. This secretion leaves damp pawprints behind nervous or stressed canines and may also improve traction for a quick getaway. The skin is subject to attack from without and from within.