Can you all enlighten me about booster shots? I have a 3-year-old inside cat. Every January we go to get her vaccinations... ie: distemper and rabies. This past January I changed vets, and a couple months after her vaccinations they sent me a postcard for her to get some booster shot. I don't remeber the name of it, but how come I've never had to get her a booster before now?? And is it even necessary??