Generally, iodine-based teat dips have effective germicidal effects on most mastitic organisms. Most concerns have been raised in the Midwest about cold weather effects on teats.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
"Dairy producers should request information from the manufacturer on compliance with FDA regulations and results of controlled research studies showing efficacy. Another source of information concerning teat disinfectant efficacy is the Summary of Peer-Reviewed Publications on Efficacy of Premilking and Postmilking Teat Disinfectants published since 1980, made available and updated annually by National Mastitis Council, now called NMC. The summary of peer-reviewed publications is not exhaustive and new findings may be reported between publications of the list. NMC recommends two methods of testing teat disinfectant effectiveness. Experimental Challenge evaluates the ability of a teat disinfectant to prevent infections in dairy cows under conditions of experimental exposure to mastitis pathogens. This protocol determines effectiveness under experimental conditions only. Natural Exposure evaluates ability of a teat disinfectant to prevent infections in dairy cows under commercial dairy practices. This protocol determines effectiveness under natural conditions." http://nmconline.org/dipfacts.htm
