hmm, I found pretty much the same thing Lori but I went ahead & read this article:
Hair Loss In Dogs (Canine Alopecia) | Tri-County Animal Hospital - Wayne, NJ Veterinarian
It sorta sounds to me like Melanoderma may be a fancy name for hair loss. The only place I saw it mentioned was in the paragraph "
Specific Locations of Hair Loss" I'm sure if we're wrong someone will come along & correct us shortly! 