My cousin is a chiropractor so of course I call him Doctor. He mentioned to me that you have to go to the same amount of training/school as an M.D. A lot of that is summarized here:

I consider chiropractors to be a type of doctor, like an optometrist, dentist, etc. This came up because I met a bunch of chiropractors yesterday, and made sure to refer to them as doctor... and they got a little embarrassed and said that it's ok. I've never had a medical doctor tell me that!

Do you consider a chiropractor a doctor?