Bridgid,
 
The basic difference is that IMRAB - 3 has been approved by the USDA for use
in ferrets, and RABVAC-3 has not.  That means in the event of a bite of
scratch to a human, the RABVAC vaccine will not be recognized by authorities
and your ferret is likely to be killed and tested for rabies.  If it were
vaccinated with IMRAB - 3, you might have a chance to quarantine your
ferret, depending on where you live and how knowledgeable the
animal-control-people/ MDs are of ferrets and rabies.
 
It's is unlikely that your ferret would even get close to a rabies carrier
unless it got outside unsupervised somehow.  Even if it were bitten by a
rabid animal and came down with rabies, the studies to date would show that
they couldn't pass the disease on to anyone or any other animal.  So the
chief purpose of a rabies vaccination is to protect the ferret from ignorant
(I use this in the context of uninformed) Public Health people.  Since they
do not recognize RABVAC (some of them still don't recognize IMRAB) don't
bother with the RABVAC.
 
You could tell your vet to look at the "Compendium of Animal Rabies Control,
1996".  That lists the approved vaccines for various animals.
 
Krinkle Sacks
These are wonderful ferret playthings.  They sound like the thin plastic
grocery store bags, but they are covered with cloth material on both sides.
I've seen some with trim too.  They really make a racket when the ferrets
get inside and they love to play in them.
 
Our guys had one, but we washed it one too many times and it lost it's
krinkle.
 
Dick B.
[Posted in FML issue 1585]