Regarding "puzzled in Colorado" with the case of a ferrret losing hair,
then regrowing, and adrenal disease:
 
my first ferret lost a good bit of her hair and was diagnosed with adrenal
disease on that basis (nothing definite showed on ultrasound at that time -
but that's not uncommon).  Her hair grew back completely a few months later
(in the fall) and then began falling out again the next spring.  My vet
said he had seen that happen on other occasions as well.  Another
ultrasound performed at that time clearly indicated bilateral adrenal
tumors (even to my untrained eyes) and her vulva had become slightly
swollen.
[Posted in FML issue 3084]