Mastitis--progress on control.

Mastitis has been investigated for over 100 yr, but progress in control has been slow. The reasons for this are complex. Mastitis is caused by several types of infection, each with a different etiology. The possible methods for control are eradication, immunization, therapy, breeding resistant cows, or by improved management factors, but in practice success has been achieved only with the latter. The first practical control was based on specific hygiene methods coupled with the improved use of antibiotic therapy. Later this was augmented by better designs of milking equipment and improved housing. By the control method it is possible to eradicate or reduce to few cows infections caused by staphylococci, Streptococcus agalactiae, and Streptococcus dysgalactiae, but control of Streptococcus uberis is much less effective and coliform mastitis is unaffected. Research indicates that these varying degrees of success are due to basic differences in the various types of infection. There is poor control with infection caused by pathogens that emanate from sources other than the mammary gland and multiply mainly in bedding material (environmental pathogens). Further progress probably depends on the degree of exposure of udders, particularly to these pathogens.