This essay maps the emergence of police dogs in the mid-1950s and 1960s United States in relation to white bourgeois fears of black criminality and insurgency. Although widely circulated images of dogs attacking black protesters in 1963 Birmingham have fashioned the police dog into a symbol of racist violence, there has surprisingly been little focus on the K-9 of this period that goes behind the terror of the image. Paying attention to the archival record of the period, I unpack the political meaning of the police dog as it relates to the policing of the “color lines” and “property lines” of racial capitalism.