This paper explores the validity of performance management regimes for quality assuring animal health regulation by comparing the results of tests for bovine tuberculosis (bTB) between male and female vets. In doing so it hopes to present some practical solutions to the regulation of animal disease and encourage further sociological study of the veterinary profession. Concerns about the quality of animal health regulation by vets have prompted thinking about the role of quality control mechanisms such as performance management systems and performance indicators. To investigate their suitability, bTB testing data from areas with high incidence of bTB in Great Britain were extracted from the Vetnet database. Using the data, a performance indicator "reactors per 1000 cattle tested" was calculated and compared with veterinarians' gender. Results showed statistically significant differences between gender and vets' reactor detection: male vets were more likely to detect animal disease than female vets. The paper considers how the concepts of "emotional labour" and "relational distance" may explain vets' behaviour. The presence of these systematic biases raises questions over the use of performance indicators as means of quality control, and highlights the need for further social scientific analysis of the veterinary profession. (Contains 6 tables.)