This paper will describe a unique relationship between thoroughbred racehorses and flat racing professionals in the British town of Newmarket. Newmarket is the historical and contemporary centre of flat racing, known internationally as « Headquarters ». Racing professionals in Newmarket practice a form of scientific totemism whereby ideas about heredity, class and gender are projected onto racehorses. The guiding axiom of racehorse reproduction, the idea that « blood will tell », is then attributed to nature and used to explain hierarchical relationships between people. I shall show how this process of purification is achieved through a series of everyday embodied practices that elide horse and human and make alternative explanations for inequality temporarily unavailable. The paper is based on extensive fieldwork in the training stables and studs of the town.