Haemophilus somnus: unlikely to be a causative microbiological agent in bovine clinical mastitis in Denmark

Haemophilus somnus is a Gram-negative bacterium, which is the cause of a clinical syndrome in cattle that may include pneumonia, myocardial abscessation, arthritis, thrombotic menin-goencephalitis, genital infections and mastitis ( Humphrey & Stephens 1983, Armstrong et al. 1986, Higgins et al. 1987, Harris & Janzen 1989, Kwiecien & Little 1992). In Denmark the infection is mainly found in the respiratory tract of calves ( Krogh et al. 1986, Wedderkopp 1991).