From the AVMA

The American Veterinary Medical Association has this to say about maximizing your chances when applying to veterinary school:

"If you've been in 4-H, FFA or a similar group, that's great experience that should go on your veterinary school admission form. Similarly, working with animals in any way can be of value. For example, volunteering at shelters or rescues can provide animal handling experience that will help make you a better candidate.

It goes without saying that volunteering or working for a veterinarian is very important. Not only does it expose you to your potential career (so you know what you're getting into, so to speak), but it also might provide a good recommendation for you from the veterinarian.

Varied experience is also helpful. If you have the opportunity to work in a research lab or for veterinarians who work with different species, that's a bonus that can make you more appealing to a veterinary school admissions committee. Get as much experience as you can while you have the opportunity."