Antimicrobial usage in Swiss fattening pig farms: is there still potential for improvement?

OBJECTIVE: The aim of this study was to analyze antimicrobial usage (AMU) in fattening pig farms that took part in the SuisSano/Safety + Health Programme in Switzerland over the year 2020 and to discuss the potential for further improvement. Usage was examined according to the antimicrobial's class and indication for use, with emphasis on highest priority critically important antimicrobials (HPCIAs). METHODS: Data on AMU from 1411 farms, reported in an electronic treatment journal, was used. AMU was quantified through treatment incidence (TI) based on Swiss Defined Daily Doses (DDDch). Indication of use for each antimicrobial class was analyzed with particular focus on HPCIAs. RESULTS: The total TI of all antimicrobials used in the farms corresponds to 8.9 DDDch per 1000 pig-days at risk, of which HPCIAs represented 2.6 %. A total of 140 farms (9.9 %) partake in HPCIAs usage, with tylosin (73.8 % of total HPCIA TI) and colistin (22.8 % of total HPCIA TI) being the most frequently antimicrobials used. The most common indication for treatment with HPCIAs was gastrointestinal disorders (62.1 % of total HPCIA TI). CONCLUSION AND CLINICAL RELEVANCE: This study shows that the efforts made in recent years to foster prudent use of antimicrobials and, especially HPCIAs in Swiss pig production, have been successful. Indeed, 90.1 % (1271 of 1411) of the farms did not use any HPCIAs over the year 2020. Of the recorded treatments, HPCIA's represented only 2.6 % of the total TIs used in fattening pigs. Since many farms do not use any HPCIAs, knowledge can be obtained from these farms to identify practices which can further reduce or even stop HPCIAs usage. Moreover, information concerning indications for HPCIAs usage provide input concerning where treatment options other than HPCIAs should be explored by both farmers and veterinarians.