The advice to give a ferret with lapsed or unknown vax a series of 2
shots to be safe could possibly do more damage than good.  The reason
for a series of shots is the maternal immunity and not knowing for each
individual when it has waned.  So you give a series to catch all the
animals and so none will go unprotected.  In essence if you waited till
the animal was 16 to 20 weeks one shot could be given.  Some will say
you are "boosting" the vaccine but you really are not by that much, and
the ones given when they still have the maternal immunities override the
vacs anyways.  Even the AVMA has acknowledged that giving boosters to
an immunized animal has little or no effect and can be harmful.  If you
have an older ferret with unknown history one shot is all that is needed.
I think in the effort to be overly cautious, people can actually be
causing damage and stress to the animal, and if you add in that a ferret
may have come from a bad situation and may not be in the greatest of
health to start with (and vaccines are NOT supposed to be given to
unhealthy animals), it is even more so.
 
I have heard this from other vets, so some vets do advise this.  At least
something to consider.
 
  ~Amy~
[Posted in FML issue 4594]