If the other has to be lost, also, look into WHEELCHAIRS.  I'm not joking.
You'll find references to ferret wheelchairs in back FMLs; I don't have
refs handy but ask your vet also for contacts at the places that make
wheelchairs for dogs, and do a search.  Recall that one which has made a
chair for a ferret is called something like "Dogone" and that there was
website at the time.
 
Given the defect, PLEASE, notify the breeders since they need to stop
breeding the problem ferrets if this is a genetic problem, whether of the
kit or of the uterine size of the mother.  Sadly, large farms won't have
records to track the line, and backyard breeders won't care, but private
breeders will and many will respond logically and responsibly.  Could you
describe ferret in terms of markings, what the defect is, source, etc., on
list, please?  Hope it is restricted to just the one leg.  One thing I
would LOVE to see improved would be for there to be some way to track lines
among all breeders, and for responsible actions to be taken when genetic
problems arise.  Wouldn't that be marvelous?
 
Bea, biting like that can indicate a dental problem; get ferret to vet or
have teeth and gums checked on your next vet appointment (since ferrets
have several of those for shots, etc.  as kits); if none shows up try
Cheweasels, and use consistent and constructive approaches.  Have seen
terrible kit biters completely stop forever when a dental problem was
corrected.
[Posted in FML issue 3176]