I know for sure that Cornell does track and I am pretty sure that U. Penn does as well. Tufts does not "track" per say, although they encourage you to focus with one of their signature programs (equine sports medicine, wildlife, international veterinary medicine, etc.). I'm not sure about other schools, but it seems as though many schools that do not overtly track still coax you to focus somewhat by requiring so many elective hours that you can take in subjects of your discretion.