Pre-vet involves a specific set of courses that vet schools require of applicants, much like pre-med requirements. Most applicants will have majored in one of the biosciences, or in animal science in an ag college. Relevant experience with animals also is an important consideration in vet school admissions. The admissions pages from the Cornells Vet College has useful information: PS:PreReqAcademic
You should check out the UIUC and Purdue vet school websites for similar information.
Some schools have programs with early or guaranteed admission to their vet schools. Some to check out are Missouri, Kansas State, and Augustana College (a program with UIUC vet school).