I think it is quite rare for vet schools to accept students without a bachelor's degree. You have to have done quite well in your required courses (we're talking 3.5 or better) and have had an extended number of hours working with animals in some degree (be it volunteered at shelter, worked in a vet's office). I have seen where they've taken older students without much animal experience, but these people have done other things that make them stand out.
Vet school is four years. You can go on to do residencies and specialize in one area of medicine. It is quite intense but if you want to do it, you find a way. Good luck with your choices!