Evaluation of 57 teat sanitizers using excised cow teats.

Fifty-seven teat dip formulations were tested for germicidal activity with an excised teat assay. Streptococcus agalactiae (ATCC 27956), Staphylococcus aureus (ATCC 29740), and Escherichia coli+ (a wild strain isolated from an Ohio cow 2956RR during the dry period) were used. Log reductions ranged from 5.6480 to 1.8330 for Strep. agalactiae compared with undipped controls. Staphylococcus aureus were reduced from 4.8972 to 1.0102. Escherichia coli were reduced from 5.8677 to 1.1450. The percentages of the products tested that had log reductions < 3 against Strep. agalactiae, Staph. aureus, and E. coli were 24, 30, and 61. Four teat dip formulations contained 4% sodium hypochlorite; all were effective against Strep. agalactiae, Staph. aureus, and E. coli. The three formulations containing glutaraldehyde were effective against the three mastitis pathogens. Formulations containing 1 and .5% iodine were not consistently effective against Strep. agalactiae, Staph. aureus, or E. coli. Teat sanitizers containing .5% chlorhexidine also showed inconsistency. Variations in formulation for products containing iodine or chlorhexidine affected germicidal activity.