Postmilking teat dipping is one of the most effective management practices to prevent mastitis. A wide variety of teat dips containing a number of different active ingredients at various concentrations are available. In an effort to standardize testing methods, the National Mastitis Council (NMC) developed a series of protocols for use by manufacturers to test teat dip products. Teat dips are tested by efficacy studies. Efficacy is determined by the ability of a teat dip to prevent new intramammary infections by mastitis pathogens. The protocols detail experimental design; selection of herds, cows, and quarters; preparation of bacterial cultures; teat dipping; sampling schedule and procedures; criteria for diagnosing infections; size and duration of trial; and presentation of data.
Teat dip efficacy studies are conducted under either 1) experimental challenge conditions, or 2) natural exposure conditions. Experimental challenge studies evaluate the ability of a teat dip to prevent new intramammary infections when teats are experimentally challenged with mastitis pathogens. Teats are experimentally challenged by immersion in a bacterial suspension containing specific pathogens immediately after milking units are removed. This protocol determines efficacy under experimental conditions only. Natural exposure studies evaluate the ability of a teat dip to prevent naturally occurring infections in cows under normal field conditions. Natural exposure with negative control compares a new teat dip product to no teat dipping. Natural exposure with a positive control compares a new teat dip product to a dip of known efficacy.
The original NMC protocols, developed in the 1970's, were designated A, B, and C. Protocol A, intended as a screening test only, measured bactericidal activity of a teat dip formulation on teat skin. Protocol B outlined procedures to determine ability of a teat dip to prevent infections under experimental challenge conditions. Protocol C outlined procedures to determine ability of a teat dip to prevent natural infections under normal field conditions.
The protocols were recently reviewed by NMC and revised to enhance scientific merit, reflect new technologies, and further ensure standardization of testing procedures. The alphabetical name designations (A, B, and C) were also dropped and changed to identify the investigative method used. The revisions do not invalidate or change the meaning of previous efficacy studies, or require that they be redone.
The NMC currently recommends the following protocols: 1) Efficacy of a Postmilking Teat Dip After Experimental Exposure of Teats to Mastitis Pathogens (compares to protocol B). 2) Efficacy of a Postmilking Teat Dip Based on Reduction of Naturally Occurring New Intramammary Infections (compares to protocol C, using a negative control). 3) Comparing an Experimental Postmilking Teat Dip with a Product of Known Efficacy Based on Incidence of Naturally Occurring New Intramammary Infections (compares to protocol C, using a positive control). Note that Protocol A is no longer recommended.
The NMC does not test teat dip products - NMC only recommends protocols for use by manufacturers to test teat dips. Be aware that no government agency requires data on the ability of a teat dip to reduce new intramammary infections. Therefore, teat dips can be manufactured and marketed without demonstrating effectiveness or safety. In this "buyer beware" market, the consumer is responsible for determining whether a particular product has been tested and proven effective. Before using or recommending a particular product, request written information from the manufacturer on compliance with federal regulations and results of controlled research studies showing effectiveness.