keeshond/hair loss

Question
7 year-old male,in- tact,black skin areas around head&neck and rear leg area,accompanied by hair loss.  He's not at all bothered by this condition. He takes no meds.  A vet familiar with skin problems tested him about 3 yrs ago ---no results or ideas. After seeing this vet, the hair grew back in,stayed for about 2 yrs and now he's lost hair in the mentioned areas again. A web search mentioned growth-hormone responsive dermatosis (sounds just like his condition).  My vet has no clue of this condition--or if this is even a real issue.With the vet 3 yrs ago,I know he tested for thyroid issues---not sure exactly what---but didn't seem to think that was the problem yet web conversation on this still points that way.  Ideas?   Thanks---TW

Answer
This does sound like a hormonal problem...either hypothyroid disease or a sex hormone problem.  Is he neutered? Sometimes to much testosterone can do this.  Growtrh hormone dermatosis does cause blackening of the skin, but it is extremely rare in older dogs and it is very difficult to diagnose.  The treatment is also unbelievable expensive.