After graduating from a classic-languages school he joined the German Navy and from 1968 through 1974 studied medicine in Kiel with a break in Hamburg and Heidelberg.
In March 1984, he went to Edinburgh and did clinical work at the Princess Margaret Rose Orthopaedic Hospital and, with a grant of the Deutsche Forschungsgemeinschaft (German Research Council), performed basic research at the University of Edinburgh (Sean P. F. Hughes).
In August 1985 he returned to Kiel, and three years later he moved to the University of Münster for spinal surgery (H. H. Matthiass).
There, he achieved his second acknowledgement as general surgeon (1992) and finished his habilitation with the neuroanatomist Werner Lierse.
Döhler operated on children from Africa and Central Asia for the Friedensdorf International and, on behalf of the Foundation Remembrance, Responsibility and Future, on former Nazi slave laborers from Poland and Ukraine.