While he was a medical school student in the 1970s, Frist performed fatal medical experiments and vivisection on shelter cats while researching the use of drugs on the mitral valve. By his own account, Frist improperly obtained these cats from Boston animal shelters, falsely telling shelter staff he was adopting the cats as pets.[5] In his book, Frist asserted that he succumbed to the pressure to succeed in a highly competitive medical school.