Will Falconer, DVM Moderator
Yeah, the bat part is pretty far fetched. Possible, but the odds of the bat getting into the house, having rabies, and exposing a pet just don't add up, certainly NOT to yearly vaccinations!
The largest understanding I've come to is "once and done." Immunity is set in for life after a viral vaccination,if given after 4 mo of age. What you do from there, whether you buy into laws that have anything but sense or your animal's health behind them, is ultimately your choice.
Avoiding thimerosol may help, but it wouldn't have stopped Lily from getting vaccinosis from her sole rabies vaccine.
Not easy, but a treacherous path that needs to be walked very carefully.
Best of luck traversing it, L.