Efficacy of enrofloxacin during the lactation against mastitis caused by Mycoplasma bovis in dairy cattle

The objective of this study was to determine the efficacy of enrofloxacin (Baytril(R)) in the treatment of mastitis of dairy cattle caused by Mycoplasma bovis during the lactation. An outbreak of mastitis was detected in two dairy herds comprising 150 and 50 cattle. After bacteriological studies, Mycoplasma bovis was assessed to be the cause in both herds. Further analysis including all cows, was conducted to identify the presence of carriers of the infection. A total of 19 infected cattle were included in the study, and treated with enrofloxacin (5 mg/kg body weight/day) for 3 consecutive days. Four treatments were conducted. Group 1: Seven cattle that received two injections administered intravenously and one subcutaneously Group 2: Seven cattle given three injections subcutaneously. Group 3: Two cattle that received one intravenous injection and two subcutaneously. Group 4: Three animals that served as controls. Three weeks after treatment, milk samples were obtained aseptically and submitted to bacteriological analysis. All the animals in groups 1, 2 and 3 showed negative bacteriological results, while the untreated cattle remained infected. The results of this preliminary study show a good activity of enrofloxacin against mycoplasma mastitis of dairy cattle during the lactation. An extensive study, however, is needed to confirm this outcome.