First, it is a legal requirement to vaccinate pet cats in many states.
Second, there aren’t any cats that never go out, there are only cats that aren’t supposed to go out.
Eventually, any cat leaves the safety of home to visit the veterinarian, to be boarded, to leap or fall out an unguarded window, etc.
There was even one case in which a New York City cat was bitten by a rabid bat that flew in through a window. A rabies vaccination is an insurance policy against the owner’s having to worry about rabies at all.
The vaccination is intended to create a barrier between wild animals that might have rabies and human beings.
It is much more likely, for example, for a lost pet that accidentally wanders into the woods to have contact with a rabid bat or skunk than for its owner to meet a rabid wild animal directly.
The initial vaccination for a kitten is good for a year.
Boosters are available that confer immunity for one year or three years.
