[Escherichia coli mastitis in cattle. I. Clinical diagnosis and epidemiological aspects]

The diagnostic aspects, incidence, risk factors and prevention of coliform mastitis are reviewed in the present paper. It is concluded that it is not possible to establish an accurate diagnosis of coliform mastitis, which is based on a specific clinical symptom differentiating it from other forms of mastitis. Not any single symptom or combination of symptoms is specific for coliform mastitis. The importance of coliform mastitis in dairy cattle showed a marked increase during the last few decades. Successful programmes for the prevention of mastitis reduced the importance of contagious organisms, but the overall incidence of mastitis has remained unchanged; therefore, the proportion of cases of coliform mastitis increased. The observation that coliform micro-organisms are common bacteria causing mastitis in herds with low bulk milk somatic cell counts implies that the future of the dairy industry will be associated with particular risks. Factors involving the risk of coliform mastitis are divided into cow level factors and herd level factors. The most important cow level factors were: leaking milk in between milkings, lesions of the teats and a reduced capacity of the immune system. Risk factors on the herd level include: the bedding material, the design of cubicles, exposure to daylight in summer-time, exposure to dirt and the use of dry-cow therapy. The possible role of antibiotic dry-cow treatment and teat dipping in colonisation resistance is discussed. Preventive programmes designed to reduce the incidence of coliform mastitis have not been very successful so far.