Antibiotics in horse breeding- a double-edged sword threatening horses in the future?

Background, relevance and direct benefit to the horse sector: Antimicrobial resistance (AMR) is a slow threat not only to human health but also to equine health and the horse breeding system of today. It is a slowly but steadily growing problem that, in the future, could potentially render antibiotics ineffective, leading to untreatable infections.Aim, hypothesis, material and methods: We will conduct a joint Norwegian and Swedish project with the aim to generate knowledge and establish a reference point regarding the occurrence of resistant bacteria and understand the biosecurity and hygiene practices that may prevent the spread and development AMR. The objective of the first work package (WP) is to evaluate antibiotic use and resistant bacteria retrospectively, while the objective of the second WP is to screen for AMR in the general horse population, with 250 samples per country. The objective of the third WP is to understand biosecurity and antibiotic use at stud farms, while the objective of the fourth WP is to map the occurrence and the risk factors for AMR in mares at the stud farms, including in total 120 resident brood mares and 120 maiden mares. We will focus on Enterobacteriaceae with resistance to extended spectrum cephalosporins and carbapenems, a type of multidrug-resistant (MDR) bacteria, which will be cultured using sensitive differentiating methods, and the MDR bacteria detected will be further characterized using comprehensive genome sequencing. Antibiotic use practice in general, and for gynaecological conditions especially, will be described using the national prescription registries, and a questionnaire will be used to assess practices related to biosecurity, hygiene and antibiotic treatments on the stud farms specifically.