An anon. poster asked for theories re: his fert's neck bump.  My mother
has a similar small bump, also discolored blue, on the side of one of her
fingers, under the skin, right near the middle joint.  It's a small cyst
(benign), and it tends to come and go.  Her doctor says that unless she
starts having serious problems with it, there is no reason to remove it.
My theory is that your ferret might have something similar.  Hope this is
helpful!
 
- Ela
[Posted in FML issue 2238]