During the pathogenesis of bovine mammary gland, bacteria are not rapidly killed by the phagocytic activity of bovine macrophages; rather, they survive within macrophages during prolonged infection due to secretion of catalase and superoxide dismutase, which by degrading H2O2, inhibit the ROS mediated killing mechanism of the host (Andrei et al., 2016; Darbaz et al., 2019). This evidence concerns the gene CAT and infection.