David Dunn attended Marquette University, graduating in 1961 and then entered medical school at the University of Wisconsin. At the time of the 1968 Winter Olympics, Dunn was a resident in neurosurgery. As a bobsledder, he was on winning four-man teams at the 1967 North American and Diamond International Trophy races. He learned bobsledding when he was on holiday in Europe, first sliding with the St. Moritz Tobogganing Club. After the Winter Olympics, Dunn had to hold off on his practice, serving for a few years first in Vietnam. He eventually took up the practice of pediatric neurosurgery in Elm Grove, Wisconsin. Obviously someone who loves speed, his hobby became racing cars.