Failure to keep mastitis caused by these two pathogens at an acceptable level is often a surrogate measure of the herd manager's skill and dedication, rather than a failure of the recommended control program. Producers have implemented traditional mastitis control programs yet their herds have continued to have new mastitis infections. Frequently these IMI are clinical, appearing to the herd owner to reflect an increased problem with mastitis even though herd and cow SCCs are low. Diagnosing the bacterial cause of mastitis in these types of herds can be difficult as ES and E. coli IMI are often of short duration. Negative milk culture results from cows with obvious clinical signs of mastitis can be common.
Appropriate samples are often difficult to obtain.
Ultimately, the recommendations made are tentative, and objective assessment of their impact is difficult to conduct. Researchers and herd advisors have sought recommendations, as explicit as those in the 5 point plan for contagious mastitis, to prevent and treat environmental mastitis. However, because of the complexity of the factors that interact to cause environmental mastitis, it is unlikely that specific procedures that work under all conditions can be generated. Herds with mastitis problems caused by ES seek help for two main reasons. A persistently elevated bulk milk SCC may be a problem because of the owner's desire to reduce mastitis, or because regulatory limits are exceeded.