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Smith, KL | Hogan, JS
 * Environmental mastitis. Control requires the veterinarian to take a wide-angle view of farms**
 * Large Animal Veterinarian [LARGE ANIM. VET.]. Vol. 47, no. 3, pp. 16-19. 1992.**

Environmental mastitis is caused by a host of microorganisms but the primary pathogens are a variety of gram-negative bacteria and species of streptococcus other than S. agalactiae. Environmental mastitis differs from contagious mastitis in that the primary reservoir for infection is the environment and not infected quarters in the herd. While exposure to contagious pathogens occurs primarily during the milking process, exposure to the environmental pathogens is continuous. Environmental mastitis occurs in all dairy herds and is the major mastitis problem in well managed, high producing herds. These herds are characterized by: Effective contagious mastitis control as evidenced by eradication of Streptococcus agalactiae and a reduction in Staphylococcus aureus infected quarters to less than 1%. Significantly reduced subclinical mastitis-less than 7% of quarters infected with major pathogens at any one point in time. Bulk milk somatic cell counts consistently less than 200,000 cells/ml. Less than 15% of cows with somatic cell counts greater than 283,000 cells/ml at any point in time.

**Descriptors:** ****Article Subject Terms**** diagnosis | disease control | environmental factors | mastitis