Effectiveness of Chlorhexidine in a Postmilking Teat Dip

Abstract

Chlorhexidine used at 0.2% in an aqueous dip for cows’ teats immediately after each milking reduced the resident microflora on the apical teat skin by about 95%. The skin microflora was evaluated as gram-positive cocci culturable on Staphylococcus Medium 110 from a standardized swabbing of washed teats. As so measured, the microbial population of untreated apical skin of a given teat is quite stable at a magnitude characteristic of the individual teat.The chlorhexidine dip was used in the same manner to sanitize half-udders of 12 cows against exposure of the entire udders to Staphylococcus aureus applied at each milking through contamination of the milking machine teat cups. During 31 weeks of such challenge, nine new gland infections appeared among the undipped quarters with a mean-day of onset of 97, whereas there were three new infections among the dipped quarters with a mean-day of onset of 153.