Prevalence and severity of lameness in lactating dairy cows in a sample of Minnesota and Wisconsin herds.

An epidemiologic study investigating the prevalence of lameness in lactating dairy cows was performed in 17 dairy herds in Minnesota and Wisconsin. The mean herd size was 50 cows. Cows from 14 herds were housed in stanchions or tie stalls, and cows from 3 herds in free stalls or dry lot. During visits to each farm in the summer and subsequent spring, 2 investigators simultaneously but independently evaluated the ambulation of lactating cows by use of a standardized scoring system. The lameness scoring system was reliable at the 2 visits, with 92.7 and 91.3% agreement between the 2 observers and kappa coefficients of 0.60. The prevalence of lameness detected by the investigators ("clinical" lameness) was 13.7% (117/853) in summer and 16.7% (134/801) in spring in lactating dairy cows. These prevalences were 2.5 times higher than those estimated by the herd managers. Parity was significantly (P < or = 0.03) associated with lameness, with higher prevalence of clinical lameness found in cows of higher parity.