Tracing over a century of transformation in the relationship between humans and our "best friend," from hunting companion to laboratory commodity to modern pet. Intrepid, docile, and cloaked in their characteristic coats of white, black, and tan, beagles were one of the most popular breeds in the United States by 1950. But during the same period, they emerged as something else: an ideal dog for laboratory experimentation. After researchers used the breed to test the effects of radiation exposure, scientists looking for subjects larger and longer-living than rodents began to turn to beagles, who were loyal, cooperative, and eager to please. In Lab Dog, historian Brad Bolman explains how the laboratory dog became a subject of intense focus for twentieth-century scientists and charts the beagle's surprising trajectory through global science. Following beagles as they moved from eugenics to radiobiology, pharmaceutical testing to Alzheimer's studies, Lab Dog sheds new light on pivotal stories of twentieth-century science, including the Manhattan Project, tobacco controversies, contraceptive testing, and behavioral genetics research. Bolman shows how these experiments evolved alongside our understanding of dogs, revealing why we now see them as intelligent companions who deserve moral protection and socialization-and in some cases, special food or daily medication. The book also offers a glimpse into the future of animal experimentation, one in which dogs are increasingly replaced by other species, as well as non-animal alternatives. Compelling and accessible, Lab Dog tells the thorny story of the beagle's participation in science, both its sacrifice and its contribution.