Lea:
 
That bump sounds to me like your vet should remove it and send it in to be
biopsied.  Ferrets, as they age, tend to get these little mast cell tumors
or epithelial lesions that need to be removed.
 
Even though it looks like a bite, because it's raised off the skin, it's
probably something that should be taken off.
 
Just my 0.02
 
Amy & Dave (and their gaggle of giggling ferrets)
RIP Ian and Elektra
[Posted in FML issue 1585]