Since it doesn't seem to have been posted yet...
 
The reason to use ferret vaccines in ferret is that some vaccines for
dogs are grown in ferrets.  When you give these vaccines to ferrets the
disease recognizes the ferret and makes the ferret sick with what you
where trying to vaccinate the ferret against.  Please not I am note a
vet.  This information comes straight out of Ferrets for Dummies by
Kim Schilling.
 
Miranda
[Posted in FML issue 4449]