My 5 year old ferret Makita has rat tail. I noticed it a week ago when I was giving her a bath, all the hair just pulled right out. Her tail is almost completely bald, except for a few straglers. I know what your going to say that she has adrenal gland diesease. But she still has a good appetite, she is still playful and shows no "depression". I lost my other ferret Honey (same age as Makita) a year ago from adrenal gland diesease. And Makita is showing none of the symptoms as Honey did. She is not shedding anywhere else, she always has ferretvite and her oil supplement (can't remember the name) Has anyone ever heard of this before?
Also, I would like to note for other ferret owners. My Honey did not loose her hair on her tail like most. She lost all of her hair between her sholder blades.

