conventional and extended intramammary therapy of persistent subclinical mastitis using nafcillin-penicillindihydrostreptomycin in lactating dairy cattle

the objective of the present study was to compare the efficacy of conventional and extendedintramammary (imm) therapy of persistent subclinical mastitis in lactating dairy cattle using nafcillinpenicillin-dihydrostreptomycin combination (npd). sixty-five dairy cows with 126 infected quarters were enrolled in the study. infected cows were allocated randomly to 1 of 3 different treatment regimens: (1) conventional group: npd administered imm 3 times at 24-h intervals (20 infected cows, 43 intramammaryinfections [imi]), (2) extended group: npd administered imm 6 times at 24-h intervals (23 cows, 43 imi),and (3) untreated control group (22 cows, 40 imi). the overall bacteriological cure (bc) rates for subclinicalimi were 86.04%, 100%, and 20% for the conventional, extended and the control groups, respectively;indicating a higher bc rate (p