I think if a ferret is going to experience a reaction to a vaccination, it must be dependent on the particular batch of vaccine and also the ferret itself. I had never had any problems with my woozles until the last time they went in for their shots. One was fine, but my youngest daughter was horrified when after about two minutes in the car, the other started vomiting all over the carrier and then my daughter's lap in the backseat. I called the vet as soon as we arrived home and they assured us that this reaction was not uncommon. After a warm bath and a little rest, the upchucking ferret was fine. On the other hand, I did once have a vaccine give my newly acquired kitten a limping strain of calici virus. It made the kitten so ill that it had to be rushed to an emergency vet in the middle of the night. I was fortunate that my cat's regular vet is a feline specialist and recognized the symptoms immediately. At the time, we didn't know if the kitten had been exposed to the virus before he received the vaccine, but several years later my vet learned that they pulled that particular formula off the market because it WAS giving cats calici. Gaye [Posted in FML issue 1821]