Study suggests mastitis treatments done wrong.
A University of Wisconsin study with 51 large dairy herds suggests 62% of cows treated for mastitis might not benefit from antibiotic treatment.
The reason: 35% of these cows have no mastitis pathogens present in milk samples and 27% have E. coli present. In both cases, antibiotic treatment often comes too late because the cow’s immune system has
already cleared the pathogen or the drugs used are not effective against E. coli.
“Of all the cows treated, 23% received an additional secondary treatment because of perceived lack of response to the initial treatment,” say University of Wisconsin researchers Leane Oliveira and Pam Ruegg.
The researchers note that most large dairy farms have primarily controlled contagious mastitis pathogens, such as Staph.aureus and Strep. ag, through routine teat dipping and dry cow therapy. The battle has moved to more opportunistic, environmental bugs, such as E. coli, Strep.species, Klebsiella and coagulase negative staphs.
These pathogens might not benefit from antibiotic treatments. Nevertheless, most dairy farms do little or no culturing to determine which bugs are causing mastitis. Most farms treat based on
observations of abnormal milk, swollen quarters or systemic illness.
The results of the study show antibiotics are being used where they have little chance of success. “It is difficult to justify the use of antimicrobials to treat most cases of mastitis that are culture negative when detected, and the cow likely experiences little benefit,” the authors note.
They conclude: “Great opportunity exists to improve mastitis therapy, but use of more diagnostic methodologies is necessary to guide treatments.”