I have a recommendation for you. If you were in the medical field (as I did) and you don't know a DO personally, interview with them and have them write a short letter of recommendation. It really isn't that important what they say because if they don't know you that well it is fairly easy to tell it is a slightly generic letter.
Then do yourself a favor. Have an MD you know write you a letter of recommendation and have them include something along the lines of....
" friedcfood has asked that I write a letter of recommendation for him because he feels that having know me for some time, I may be the most qualified to write him a letter"
I interview candidates at my school, I can tell fairly quickly if a letter from a doctor is personal or generic (a generic one does not hurt your cause, some docs are just lazy). I am much more impressed by an applicant who sends in an MD letter that is personal than a generic DO letter though. Also, I sent an an MD letter for the same reason. I even pulled my application from the school in Arizona because they refused at the time to accept anything but a DO letter and I thought it was personally un ethical to ask someone who hardly knows me to write me a letter of recommendation, wereas I had worked directly under an MD for some time.