Black Skin Disease
October 23, 2012
Hair loss (alopecia) accompanied by darkening of the skin (hyperpigmentation) is often termed “black skin disease”. Other names applied to this condition include wooly coat, coat funk, pseudo-Cushing’s syndrome, and severe hair loss syndrome.
In Pomeranians, this condition is suspected to be an X-linked inherited disorder since many more males than females are affected, and research is being carried out to identify a linked gene marker so that dogs in this breed can potentially be tested for the condition. Other breeds with increased prevalence of black skin disease include the Alaskan Malamute, Keeshond, Poodle, Dachshund, Chow Chow, Samoyed and American Water Spaniel.
Many of the afflicted dogs are diagnosed with growth hormone responsive alopecia. Not all affected dogs have abnormal growth hormone levels though, and though many affected dogs develop abnormal signs after puberty, dogs of any age can be affected. In Pomeranians, late onset signs are sometimes associated with reduced 21-hydroxylase levels, enzymes which are involved with processing of some of the reproductive hormone precursors.
Currently, the condition is still considered to be of unknown cause since similar signs of hair loss and black skin are not consistently associated with a standard set of hormone changes. Other conditions that can mimic this condition include Cushing’s disease, hypothyroidism, chronic skin infections, and reproductive hormone disorders that should all be ruled out by testing.
If the condition is due to a laboratory confirmed growth hormone deficiency, hormone therapy is instituted. Benefits last from six months to a few years. As hormone therapy can produce diabetes as a side effect, so the attending veterinarian will recommend close monitoring of the urine and blood sugars weekly during treatment.