The future of udder health: Antimicrobial stewardship and alternative therapy of bovine mastitis.

Although antimicrobial usage is highly restricted in dairy cows, concerns about development and dissemination of resistant bacteria have led to a reexamination of mastitis therapies. In the past, almost all cases of clinical mastitis were treated symptomatically using intramammary antibiotics, and in many regions, most cows received intramammary antibiotic treatments at dry-off. On modern dairy farms, changes in the distribution of etiological agents have reduced the need to give antimicrobials for all mastitis cases. Culture-guided selective treatment protocols for nonsevere clinical mastitis have been adopted on many farms and align with principles of antimicrobial stewardship. Although some antimicrobial therapy is needed to maintain udder health, antimicrobial therapy is not effective or not necessary for resolution of many cases of mastitis. As the use of antimicrobials has declined, many alternative treatments have been explored, but few non-antimicrobial treatments have documented efficacy. The purpose of this paper is to review the concepts of antimicrobial stewardship on dairy farms from the US perspective, with an emphasis on current and future management strategies for udder health.