It depends on the school, the program, the individual teachers, and YOU. Veterinary Technicians can go to school anywhere from 2-8 years.
Here are a couple questions that may help (not with college years, but with the whole realm of Veterinary Medicine):
1. Are you wanting to get a Doctrites (DVM) in Veterinary Medicine?
2. Are you wanting a basic degree to help you with YOUR pets? Or with others'?
3. What are your future plans? (a biggie)
4. Do you mind going to school for a long time?
5. Are you going to enjoy studying about blood, parasites, insects, and other seemingly "gross" things?
6. Do you mind dissecting animals like cats, dogs, horses, cows, etc?
7. Would you have the skills and the patience to operate on an animal? (most vet techs as well as DVM veterinarians need to do so)
By 2-8 years, I'm not talking about in total. Those are just the years that you'll be putting in for your degree. You have two more years where you get your undergraduate. Some schools and some majors you don't NEED an undergraduate for studying it, but Vet work, (actually, anything with medicine) needs the basic biology and chemistry classes that you get in the first two years of College.
I'm not trying to discourage you. But to help you. I'm not an expert. I'm looking into these things as well. I'm not going for Vet Tech, or Veterinarian Paramedic, but I'm going for the whole shebang... aka, a DVM in Veterinary Medicine.
For the biggest things, I wouldn't say it's "how many years" as much as "which school?"
If you're wanting just a basic Vet Tech degree, most state, community, and "major" schools will offer something. BUT, if you're looking at getting a DVM, you'll have a bit more trouble. I'm talking about the United States when I say this: There are only 28 schools in the whole of the US that offer a doctrites degree in Veterinary Medicine. Makes it a whole lot harder to find something? Right?
Good luck with this. And wish me luck. It's a great profession, and I hope it's as right for you as it is for me.