Hi,

This may not apply in all countries, due to the different usage of "doctor" in the United States, and the fact that the US has two different degrees programs by which a person can become a medical physician. 

Is it permissible to write Dr. "My Name," M.D. in order to distinguish it from Dr. "My Name," D.O.?

Some physicians would prefer that the uniqueness of their degree be acknowleged, but also like to use the "Dr." title to make it more clear for any patient who might not understand that an M.D. or a D.O. are "doctors."

It's permissible, in the sense that the police won't put you in jail if you do this.   However, it just seems to me rather unsophisticated.

My doctor's card just reads

Dr. J. B. Smith

Family medicine

How about something like that, where you just specify your type of practice? 

Best wishes, Clive