Dorothy M. Horstmann

Horstmann was born on July 2, 1911, in Spokane, Washington and earned her undergraduate degree in 1936 from the University of California, Berkeley. She received her medical training at the University of California, San Francisco, earning her medical degree in 1940 and developed an interest in infectious disease after hearing lectures delivered by Karl Friedrich Meyer while at San Francisco General Hospital, where she performed her internship and residency. She performed further training at Vanderbilt University Hospital.

Horstmann had initially been rejected from the residency program at Vanderbilt as the school's chief of medicine Hugh Morgan only chose men to participate. Months later, she received a letter from Morgan asking whether "Dr. Horstmann" was still interested in the position. He obviously had forgotten that his original reason for exclusion of the applicant was because of gender. She replied with an acceptance of the position. When she showed up for work, Morgan "all but went into shock", but the year ended successfully.

Hired by the Yale School of Medicine in 1942 as a Commonwealth Fellow in the Section of Preventive Medicine, Horstmann specialized in internal medicine under Dr. John R. Paul. She spent 1944 teaching medicine at the University of California, San Francisco, but returned to Yale the following year. Horstmann continued her work at Yale with a joint appointment in both the department of pediatrics and the department of epidemiology, which became part of a newly created Yale School of Public Health.