My D.O. letter came in a little late although I had known the D.O. that I shadowed for quite some time. I was accepted to all of the schools, that I interviewed at, that either did not mention, recommended or highly recommended having a D.O. letter before the letter arrived at the given schools. For the schools that actually required the letter, they held off looking at my application until they received it.
However, shadowing a D.O. and getting a LOR from him or her can only benefit you. Having a D.O. letter demonstrates that you've, at least, made an effort to learn more about osteopathic medicine from a first-hand source. Also, during interviews, adcoms typically ask what experiences you have had with osteopathic medicine and why you feel osteopathic medicine is a good fit for you. One of the best ways to articulate your interest in the field is by relaying your shadowing experiences. So, although I was lucky enough to get in without the letter, I would still recommend that you try to find a D.O. to shadow and write you a letter. It can only help. Good luck.
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