The Efficacy of Teat Dips of Differing Persistence on Teat Skin In Preventing Intramammary Infection By Streptococcus Uberis and Escherichia Coli in Dry Cows

The persistence of disinfectant activity on teat skin was tested for three materials, ethanol, iodophor and chlorhexidine, using Streptococcus uberis and Escherichia coli as test organisms either 15min or 15h after the application of the disinfectant. All materials showed marked bactericidal activity 15min after application but only chlorhexidine retained this activity after 15h. The same materials were then tested in 48 cows for their ability to prevent infection in the early dry period. All teats were contaminated daily 15h after disinfection with a mixed suspension of Streptococcus uberis and Escherichia coli. Fourteen days later 26 udder quarters became infected when the teats were dipped in ethanol as did 26 undipped quarters. Twenty-two quarters treated with iodophor became infected whereas only 15 chlorhexidine-treated quarters were infected, Eighty- three percent of the infections detected were due to Streptococcus uberis. It is suggested that persistence on teat skin may be an important property for a disinfectant to prevent Streptococcus uberis mastitis.