Some years ago, Streptococcus agalactiae (Strep ag) was a relatively widespread cause of mastitis in the Australian dairy industry.

It was then commonly known as “Contagious Mastitis”, due to its ability to spread rapidly in a herd.

Because cure rates for treatment of Strep ag are remarkably high, the widespread uptake of antibiotic dry cow therapy into a seasonal milking system nearly eradicated Strep ag from many regions of Australia.

However the trend towards both split and year-round calving, combined with widespread movement of cattle as herds have been sold and disseminated, has seen Strep ag begin to re-appear as a significant cause of mastitis in Australia.