A systems thinking approach to identify barriers and strategies to improve antimicrobial stewardship using a bottom-up approach among Danish pig veterinarians.

Understanding the drivers and barriers to antimicrobial use (AMU) is crucial for developing effective reduction strategies without hampering animal health and welfare. A survey was distributed to all Danish pig veterinarians (n = 73; 58% responded) to gather input on their views and behaviours on antimicrobial (AM) prescriptions and the effectiveness of AM stewardship strategies. Quantitative data were statiscally analysed to identify the relationship between work experience and continued education against practices in AMU. Open-ended responses were processed using Grounded Theory. Results were used to develop a systems thinking map and iceberg model to illustrate the interrelationships between internal and external elements of AMU practices and to identify leverage points for change. Most respondents (87%) adjusted their AMU practices over time, predominantly influenced by legislative restrictions. Respondents identified key practices enabling AMU reductions, including strict gilt acclimatisation protocols, all-in/all-out systems, improved feed quality, and adequate ventilation. Perceived key barriers to further reducing AMU included financial constraints, a lack of effective alternatives to AMs, and limitations in the pig housing system. Respondents emphasised the need for cost-effective vaccines, better and faster diagnostic tools, and the implementation of eradication protocols as future strategies to reduce AMU. Several legislative requirements influenced AMU patterns, unintentionally increasing aminoglycosides and macrolides usage. Our findings emphasise veterinarians' pivotal role in implementing AM stewardship, bridging regulatory frameworks and on-farm practices. Future efforts should focus on enhancing the feasibility and effectiveness of AMU reduction strategies, ensuring they are supported by robust scientific evidence and feasibility analysis.