Thank you all for your comments. Adrenal gland disease is when tumors grow in the ferrets adrenal glands. The first sign of the disease is hair loss. We had Trouble on hormone shots but in time the tumors won, his tumors were unfortunately inoperable. Hopefully, if it does turn out that Sebastian's hair loss is being caused by adrenal gland disease, he will be a good candidate for the surgery that could give him a lot longer with us. For now we keep a close eye on his fur and see if he loses more or if he "hairs up" for winter. I pray that my little fuzzy gets his hair back.