It's best to just look at each schools website to be sure of which and how many prerequisites are needed. Usually Microbiology, Anatomy and Physiology, Statistics, and Nutrition are required. Sometimes chemistry and/or psychology classes are required as well.
Edit: I realize that I may have misunderstood your question, but my advice would still be to check with the schools. It's best to have more prerequisites completed than less because it can bolster your application. However, I only had 2 out of 6 or 7 prerequisites completed for the DE program I am starting in the fall. Mind you, I was initially wait listed and I also had several biology and chemistry courses that demonstrated my proficiency in the hard sciences.
Last edit by hi616 on Jul 3, '13