Todd and Sheldon,
 
It is common for ferrets with adrenal tumors to lose hair.  This is probably
because the high level of estrogen in their blood has many effects including
making the hair more likely to fall out of the hair follicle or arresting
the development of the hair follicle (the exact mechanism is not known).  As
a result even when the tumor is removed (and the estrogen level drops) the
loose hairs have to come out of their follicle before new hair comes in.
this is why some ferrets "blow coat" prior to new hair growth after adrenal
surgery.
 
Dr Weiss
[Posted in FML issue 1321]