Trends in estimated intramammary antimicrobial usage in the Irish dairy industry from 2003 to 2019

Abstract

Understanding antimicrobial (AM) usage is key to safely reducing AM use in food-producing animals as part of addressing the global public health threat of AM resistance. We estimated intramammary AM usage from national sales data for the period 2003 to 2019, updating an earlier work. Descriptive trends in AM use are presented. We observed some reduction in dry cow AM use when accounting for cow numbers; however, use of blanket dry cow therapy is still widespread. In addition, there is evidence of ongoing use of highest priority critically important AM. This study provides objective evidence in support of efforts to direct and prioritize urgent changes in AM prescribing and usage as well as securing farm-and prescriber-level data in Ireland. Highlights• Blanket use of dry cow AM therapy is still very common in the Republic of Ireland.• There is evidence of ongoing use of highest priority critically important AM.• We identify key knowledge gaps and areas for urgent review in AM prescribing practices and acquiring prescriber-and user-level data.

The new Veterinary Medicines Regulation: rising to the challenge

“…In Ireland, there are both challenges and opportunities in the coming period with the introduction of this Regulation. A substantial shift from current practice will be needed, both for PVPs and farmers, noting that there have been only tentative steps to this point towards selective DCT, a worrying recent upward drift in national sales of EMA Category B intramammary AMs (3rd and 4th generation cephalosporins) [ 7 ], and ongoing limited penetration of milk recording across the national herd [ 13 ]. Education will be critical to ensure a smooth transition.…”

“…This remote (or so-called Schedule 8) prescribing is estimated to account for approximately 30% of all tubes prescribed for dry-cow therapy. There are ongoing concerns about the application of remote prescribing in Ireland, including by McAloon et al ([ 7 ]) who suggested that ‘this prescribing route is unlikely to provide the veterinary oversight necessary to support prudent prescription decision making on the basis of a detailed, on-farm understanding of mastitis and farm management’. AM stewardship is further compromised by the potential for Irish farmers to source intramammary AMs from multiple sources.…”

“…Category B (including 3rd and 4th generation cephalosporins) should not be used as first line treatments, and only used for treatment when there is no alternative AM in a lower category (C or D) shown to be clinically effective based on the results of AM sensitivity testing [ 10 ]. The widespread, and increasing, use of 3rd and 4th generation cephalosporins (Category B AMs) in Ireland, both for in-lactation therapy and DCT [ 7 ] is of particular concern, and at odds with these guidelines. Analyses of the national intramammary AM sales data from 2020 have confirmed these trends (McAloon CI, McCoy F, More SJ: Intramammary antimicrobial sales in Ireland: a 2020 update, under review).…”

Intramammary antimicrobial sales in Ireland: a 2020 descriptive update

“…For this reason, intramammary (IM) AM sales data are currently the only feasible means to gain broad insights into on-farm usage of AMs relevant to mastitis control within the Irish dairy industry. Published information is available for the period 2003-19 [ 6 – 8 ], with key themes including near-universal blanket dry cow therapy across the national herd until very recently, a progressive fall in in-lactation therapy since 2013 (to a defined course dose (DCD)/cow of 0.43 in 2019), and ongoing concerns about both the use and trend in use of highest priority critically important AMs (HP CIA) in IM products, both with in-lactation and dry-cow therapies.…”

“…Therefore, the aim of this study was to update the earlier work of More et al [ 7 ] and McAloon et al [ 8 ] as a descriptive update of IM AM usage in the Irish dairy industry to include 2020 sales data. The data from 2013 to 2019 has already been reported and is included for reference purposes, reported comparisons are between 2019 and 2020 only.…”