I am bad at responding to emails & I don't even work outside of my farm at this point in my life. The one time he did respond was before he started loosing his receptionists & started getting overloaded with work to keep his practice going. Remember, after each patient, he also has to make notes for those who have insurance or he doesn't get paid & also, they are required to do that same paperwork for All their patients, so having time for responding to emails at this point in his career might be very difficult which is why you aren't getting the replies you expect.

Sometimes we need to look at their situation & adjust our expectations appropriately. Would it be better if he told you not to email because he doesn't have time to reply?