Herd Mastitis Problems Caused by Unusual Pathogens

Abstract

Until recently most mastitis was caused by two species of bacteria-Streptococcus agalactiae and Staphylococcus aureus. Today, these two bacteria are controllable in most herds by combined regimens of teat dipping and dry cow treatment. However, these control methods are less efficacious against other pathogens which may become, or appear to become, more important as the prevalence of Str. agalactiae and S. aureus is reduced. Usually such problems are caused by bacteria endemic in the cows environment, the so-called environmental pathogens. Occasionally a point source of infection may develop that leads to an outbreak of disease caused by a single unusual organism. In this paper, we will consider current thinking about environmental mastitis and then discuss herd mastitis problems caused by Pseudomonas aeruginosa and Serratia marcescens.