They can be food allergies, or they can be a sign of vitamin and mineral deficiencies or they can be a sign of microscopic mites, or all of the above. (lowchensaustralia.com)
Mange is a skin condition in dogs and other mammals caused by microscopic mites. (dogcare.dailypuppy.com)
In actuality, most healthy dogs actually have a natural microscopic mite population in small numbers, deep within the hair follicles already in residence. (thewholedog.com)