To Erci,
 
One of my ferrets had a balding tail.  He had a sparse amount of guard hairs
and no undercoat on the tail, aswell as those black dots scaly skin.  I
don't know if it was just a change in coat, but I don't think so because
this balding problem was only on his tail.  We did however change the food
he was eating(from kitten food to ferret food "Hagen's Ferret Diet").  And
after about three or so weeks his tail started getting furry.  How long have
your ferrets had this hair problem?  I hope it grows back.  Good Luck!
 
Best Wishes,
Lenka
[Posted in FML issue 1436]