Demodectic mange, also called demodicosis, is an immune reaction to mites that naturally occur on skin. All dogs have the mites, not all dogs react. Veterinary opinion varies, but most seem to agree that if the disease occurs in a young animal and remains localized it is not hereditary. Localized demodicosis will go away whether you treat it or not. It arises from a temporary compromise of the immune system in a puppy or young dog whose immune system is still developing.
Generalized demodicosis starts much like localized. However, it requires treatment and will recur periodically throughout life. In severe cases the mange spreads across the body and can be life-threatening. Not all dogs respond to medication and some will die of the disease. Generalized demodicosis is hereditary, though the mode of inheritance is unknown.
Dogs which have the generalized form should not be bred. First-step relatives (parents, offspring, full- and half-siblings) should not be bred close on either side of the affected dog’s pedigree nor to mates who have a family history of generalized demodicosis or autoimmune diseases.
Generalized demodicosis is not an autoimmune disease because the mites, while natural skin residents on dogs, are not part of the dog’s own body. However, ASHGI has observed that the disease tends to be reported in dogs who have a family history of autoimmune diseases. Therefore ASHGI classifies generalized demodicosis with autoimmune diseases for pedigree analysis purposes.