canis- to not give rabies is asking for trouble. If your dog bites someone, there is only one way to insure the dog doesnt have it- KILL the dog.. Most people will not allow you to isolate your dog for the time period- and they will kill your dog..
I give rabies now every two years because where I live on this mountian, they do run into wild animals- its for their protection more than anything. However- when I lived in the city, it was every 3 years..