W.H. Miller, Jr., VMD, DACVD
Thyroid hormone is necessary to initiate the anagen phase of hair growth and all hair follicles, except those on the head and distal limbs, appear to be under its influence.
Hair is rich in protein and its growth requires adequate nutrition and the metabolic capability to process and utilize those nutrients. The hair follicle has three phases of growth: anagen, catagen, and telogen.
Virtually all internal diseases will eventually have cutaneous manifestations such as a dull dry coat which sheds easily and is not replaced at a normal rate. In these conditions, the clinical signs of the internal disease occur first and predominate, leading the clinician down the correct diagnostic pathway.
History (70% of the battle); physical examination (20% of the battle)
This was a commonly diagnosed disease in the late 70s and early 80s. It is rarely diagnosed today. With current day tests for infectious diseases like leishmaniasis and our understanding of the complexities of cutaneous drug reactions, most cases of "lupus" are actually not "lupus" and might be a curable disease.
Currently there are 3 morphologically separate species of follicularly oriented demodex mites in the dog: Demodex canis, Demodex injae, and Demodex ?. The unnamed species has a very short tail but is not Demodex gatoi of the cat.