I am a high school student. Should I take Advanced Physics or Advanced Chemistry?

I have to agree with the other comments. I'm a Physics major and I considered going into Animal Sciences as well. At my university at least, they only require animal science/pre-vet students to take two basic-level Physics courses, but more than that are required for Chemistry, so it would probably be better for you to get a head-start on the Chemistry, although either one would still be great for you to do.