Drawing on sensory, animal, environmental, and Japanese American history, this article explores Cat Island, Mississippi, site of a top-secret Army dog training program during the Second World War. Based on the theory that different races emitted distinct scents, the project attempted to train dogs to detect Japanese people, with the goal of deploying them in the Pacific theater. To develop the canine’s olfactory skills, the Army used Japanese American soldiers as bait. The project failed because William Prestre, the project’s director, sought a stable and immutable conception of race and the environment that did not exist. Military officials focused on the strategic value of the dogs and were circumspect about the existence of a racial odor, whereas Japanese American soldiers derived enjoyment from their activities along the Gulf Coast. Thus, constructions of race and environment were highly malleable, even during the short tenure of the Cat Island project.