Field observations on the incidence of bovine clinical mastitis and teat diseases.

The incidence of bovine clinical mastitis, thelitis and teat wounds was investigated in 283 herds over a period of eight years (about 2590 cows per year). The incidence of clinical mastitis treated on farm visits was 0.102 cases per cow per year and the total incidence with cases treated by phone orders was about 0.26. The incidence of mastitis increased 6% per year. Mastitis occurred more frequently in March-April. The peak of seasonal variation of thelitis (incidence 0.032) was in April-May and that of teat wounds (incidence 0.008) in June-September. The size of herd and participating in milk recording affected the incidence of mastitis. The type of housing affected the incidence of teat diseases but not that of mastitis. Herds with a high incidence of mastitis also had a high incidence of thelitis, r = 0.41.