Bovine Mastitis: A Review

Abstract

The principal organisms associated with mastitis are Streptococcus agalactiae, Streptococcus uberis, and Micrococcus pyogenes. These organisms usually cause a chronic mastitis and a loss in milk yield with or without the appearance of clinical symptoms. Mastitis due to other organisms is not common, but may be a serious problem in an occasional herd, especially following udder infusions improperly administered. When cultural tests are made on incubated milk, the leucocyte count must be used in interpreting the results, and when made on fresh milk, consideration must be given to the number and kinds of organisms present. S. agalactiae can be eradicated from most herds by good sanitation combined with frequent cultural tests and treatment of all infected quarters. The sanitary measures now in general use are inadequate to prevent new and reinfection with M. pyogenes and S. uberis. Thus, treatment of infected quarters is of limited value. Degree of exposure to infection, natural resistance of individuals, age, stage of lactation, and prolonged milking duration influence the rate of udder infections. Abusive machine milking, especially prolonged milking and use of worn or poorly designed teat cup liners, tends to increase the rate of clinical mastitis in infected quarters. © 1958, American Dairy Science Association. All rights reserved.