Introduction
“Black Skin Disease” is not a disease per se, but instead is a phrase used to refer to a form of hormonally-influenced, symmetrical hair loss and hyperpigmentation in dogs. The term for this condition preferred by breeders and by veterinarians – especially veterinary dermatologists - is “Alopecia X.” A number of other names are used as well.
How “Black Skin Disease” Affects Dogs
Alopecia X has been diagnosed in dogs of all ages and breeds, regardless of their spay/neuter status; however, it seems to occur in males and in certain breeds more frequently than others. Affected dogs typically have normal hair coats as puppies. They begin to develop hyperpigmentation and hair loss in adolescence to early adulthood, usually by three years of age. Alopecia X is a form of patterned baldness, which means that it is symmetrical. Affected dogs lose their long primary hairs first, leaving the soft, fuzzy secondary coat underneath. This puppy-coat in turn becomes dry and cottony. Over time, even the puppy-coat falls out, leaving the skin bald. The hairless areas tend to spread but normally are not itchy, painful or prone to infection. Darkening of the skin generally follows the hair loss in somewhat symmetrical blotchy patches. Some dogs never re-grow their coats; if they do, the hyperpigmented skin usually peels away, exposing fairly normal-looking skin underneath.
Causes of “Black Skin Disease” in Dogs
Little is known about this condition or its cause. Suggested contributing factors include obesity, hormonal imbalances, allergies and heredity. It may be that Alopecia X is not a single disease but rather a combination of several, making diagnosis and treatment much more difficult.
Preventing “Black Skin Disease”
Since the cause of this condition is not well understood, preventing it is not plausible. Certainly, weight management can prevent obesity as a contributing cause. Because stress seems to exacerbate the signs of Alopecia X, castration/spaying, diet changes and other hormonal or environmental management protocols may help to reduce the effects of stress and thereby reduce the hair loss and pigmentation changes associated with this disorder.
Special Notes
Alopecia X does not appear to affect a dog’s health. It seems to be a purely cosmetic issue for owners of affected animals, and benign neglect is often the recommended “treatment” of choice. Other conditions can be confused with Alopecia X, and currently there is no medical test that is definitively diagnostic of this disorder. A veterinarian must rule out a number of other problems, particularly hypothyroidism and Cushing’s disease, before arriving at a diagnosis of Alopecia X as the cause of symmetrical baldness.