Trying to diagnose the type of mastitis by its clinical signs is not accurate and often incorrect, says Phil Sears, Michigan State University veterinarian. Almost anyone can use milk cultures to make current mastitis decisions when choosing the best antibodies for the farm or choosing cows to treat. However, culturing cow’s milk to make future treatment decisions can be misleading.
The next case of clinical mastitis may not be the same organism as the one you just cultured. Using a milk culture to identify the bacteria before treating requires withholding antibiotic treatment for 24 hours before starting antibiotic treatment.
In a study on a large Michigan dairy farm, waiting 24 hours before starting antibiotic treatment did not adversely affect the outcome of the infections or jeopardize the health of the animal. Mastitis episodes did not last longer and fewer days were lost to milk withholding for residue and unsalable milk. This protocol reduced treatments by 80 percent and saved on treatment costs.
Because of these results, many dairy farms have begun to use local veterinary laboratories or to establish “on-farm” diagnostic testing to culture milk before starting antibiotic treatment.
However, before these diagnostic-treatment protocols can be used in dairy farms, someone must be assigned and trained to do diagnostic testing, cautions Sears. This person also should be responsible for treating mastitis cases and monitoring cows with mastitis. If clinical mastitis is viewed as a catch-as-you-can by milkers, then this protocol will not be successful.
Source: Michigan Dairy Review