I know how you feel when you are trying to count and come out wrong.  We
have to recount several times when we count the piglets.  When we give
them shots we take the blue coat and mark them.  We try to blow on it
enough to get it dry so it doesn't mark everyone else.  This is the only
thing we have been able to come up with that helps us.  Don't know what
you could use to mark them with.  The blue coat only lasts about a day and
then it is gone but that is with pigs, I am sure with some other animal it
would stay there until the end of time.  We have tried putting them in a
different pen until we have every one done, but the sows really don't like
this and is somewhat mad about us messing with them anyway but it might
work for the ferrets.
 
Hope this helps.
 
Molly
Wilson's Feed and Stock
 
http://msnhomepages.talkcity.com/SuburbanSt/wilsons-feed-stock/index.html
[Posted in FML issue 3737]