This article examines the controversy over the use of a DNA marker test for Tibial Hemimelia (TH) by North American Shorthorn breeders. The conflict illustrates, first, that tools available to remove defects are not necessarily used to eliminate them from the herds; and, second, that a centuries-old breeding method can adopt twenty-first-century biotechnology to support the historic structure of purebred breeding. Shorthorn breeders attempted to hold their slipping position within the purebred beef cattle world by utilizing biotechnology to re-enforce the nineteenth-century system with its emphasis on pedigree standards and the show system. The situation provides a venue for studying a larger question: How does developing science interface with industry structure and culture when it comes to animal breeding? The subservience of genetics and biotechnology to the dictates of purebred breeding in Shorthorn affairs shows how resilient older practices can be.