I decided to stop vaccinating my ferret Odin (now over the Rainbow Bridge) after he had a small vaccine reaction. He lost a patch of hair on his back that never grew back. (he later had adrenal problems, but this wasn't associated). About 4 years after I stopped vaccinating him, I had the chance to adopt a puppy that was recovering from distemper. I didin't want to risk my boys health, so we drew a distemper titer on him. (I am a vet tech and this is routinely done for dogs and cats that have vaccine reactions). The lab has a specific test just for ferrets. Well 4 years after his last vaccination he still had a very strong protective titer. My point being, if you ferret has a vaccine reaction, why don't you get a distemper titer pulled w/ your yearly bloodwork? Most ferrets will still be protected. Freya & Loki [Posted in FML issue 3680]