We've found over the years that ferret's nails tend to get thicker with
age and they grow more slowly.  They become much duller than the razor
nails of a year old ferret.
 
The nails don't usually get brittle -- I would assume if they were
brittle and there were other symptoms (sometimes I've noticed that when
a ferret is sick their whiskers will begin to break off at the end) that
they should probably go in for a good blood work-up and physical.
 
Amy, Dave, Sarah & Paul (and their gaggle of giggling ferrets)
RIP Ian, Elektra, Claudia & Sidney
Missing Tasha
[Posted in FML issue 3954]