Prevention of bovine mastitis by a premilking teat disinfectant containing chlorous acid and chlorine dioxide.

The objective of this study was to evaluate the efficacy of a premilking teat disinfectant for the prevention of mastitis in dairy cows under natural exposure conditions. Predipping was compared with a negative control using a split udder experimental design. All teats were dipped after milking with the same teat dip. Percentage of quarters newly infected by major mastitis pathogens was 34% lower in quarters with teats predipped and postdipped than in quarters with teats postdipped only. New IMI by Streptococcus uberis and Staphylococcus aureus were significantly lower in quarters with teats predipped and postdipped than in quarters with teats postdipped only. Differences in incidence of clinical mastitis between treatment groups approached significance. Predipping and postdipping were no more effective against Gram-negative bacteria, coagulase-negative Staphylococcus species, and Corynebacterium bovis than postdipping only. No chapping or irritation of teats was observed, and no adverse effects were noted using the test product as a premilking and postmilking teat disinfectant. Results of this study suggest that predipping and then postdipping with the test product was a more effective procedure against major mastitis pathogens than postdipping only.