Prevalence of chronic teat-end lesions and their relationship to intramammary infection in 22 herds of dairy cattle.

A field study that involved 22 herds of dairy cattle (1,055 lactating cows, 126 nonlactating cows, and 32 heifers) was done to determine the prevalence of teat-end lesions and their relationship to intramammary infection. Teats were grouped into 4 general categories: normal teat ends; smooth, chronic ring lesions; rough, chronic ring lesions; and acute teat-end lesions. Only 15.8% of the teats could be classified as normal; 63.1% had smooth, chronic ring lesions, 13.8% had rough, chronic ring lesions, 0.3% had acute teat-end lesions, and 7% could not be classified. The level of intramammary infection was determined for each teat-end classification. Milk samples were obtained from each mammary gland of all lactating cows. The prevalence of intramammary infection in glands with normal teat ends and in those with chronic ring lesions was not significantly different. Glands with acute teat-end lesions and those in cows in which the teat had been traumatized or leaked milk had higher rates of infection.