The type of vet is important in factoring into your decisions as well. Do you want to become a research vet or a practicing vet? Are you eventually going to try to own your own practice? If so, perhaps you might want to look into economics. Any class that you take will help you on your journey to become what you want to be. That is the purpose of high school (ie. english will help you write reports on your studies, history can help you understand precedences for your work, etc.)

all classes that you take in high school will be essential on your way to becoming a vet. However, you should at least take Biology and Chemistry. If possible, take AP courses in both, allowing you to get ahead on college level courses. Also, if Organic Chemistry is available, you should take that too. But don’t forget that your career requires all aspects of your education, not simply what looks applicable.