This article tracks the transformation of beagle dogs from a common breed in mid-twentieth century American laboratories to the de jure standard in global toxicological research by the turn of the twenty-first. The breed was dispersed widely due to the expanding use of dogs in pharmacology in the 1950s and a worldwide crisis around pharmaceutical safety following the thalidomide scandal of the 1960s. Nevertheless, debates continued for decades over the beagle’s value as a model of carcinogenicity, even as the dogs (...) became legislated stand-ins for human beings in multiple countries. Situating beagles as a biocommodity, the article calls for more sustained attention to the “political economy” of laboratory organism breeding, use, and production. The story of American commercial breeder Marshall Farms offers insight into the role of for-profit companies in contemporary laboratory animal provision, as the article makes a case for the value of a global perspective on transnational corporations as key sites of scientific practice and collaboration. (shrink)