Alopecia X, sometimes called black skin disease, is difficult to diagnose. Many other conditions can be confused with Alopecia X, and currently there is no medical test that can definitively diagnose this condition.
Faced with a dog whose hair is thinning gradually and symmetrically, a veterinarian will want to perform a thorough physical examination and take a detailed history from the owner. Because this condition can mimic so many others, diagnosis can only be made by ruling out other possible causes – called diagnosis by exclusion. Some disorders that can look like Alopecia X include hypothyroidism, hyperadrenocorticism (Cushing’s disease), functional tumors of the gonads, infection and/or inflammatory disease of the sebaceous glands (sebaceous adenitis) and other forms of hair follicle dysplasia.
Veterinarians can take a skin biopsy and submit it to a pathology laboratory for analysis. In cases of Alopecia X, the results of this test typically are non-specific and provide little assistance in development of a treatment protocol.
Alopecia X is a cosmetic condition that does not appear to adversely affect a dog’s health in any way, other than possibly creating an increased chance of sunburn damage to the exposed areas. Most dogs characteristically retain hair on their heads and legs. Re-growth of hair is highly variable and difficult to predict.