Lynn,
The following is the vaccination schedule I recommend:
1)For young ferrets (6-10weeks of age)--distemper vaccine every 3 weeks for
a total of 3 shots, then yearly.One rabies shot at 16 weeks, then yearly.
 
2)Ferrets over 10 weeks----Two distemper vaccines 3 weeks apart, then
yearly.  Rabies vaccine at 16 weeks then yearly.
 
3)Ferrets of unknown history and age (but over 10 weeks)-----Two distemper
vaccines 3 weeks apart, then yearly.  Rabies 2-3 wks after the second
distemper, then yearly.
 
If your ferrets are already recieving their yearly shots they should be
fine, even if they missed their first round of shots (they would have been
susceptable to distemper at that time but not now).
 
Dr Weiss
[Posted in FML issue 1342]