Antimicrobial use in farm animals might contribute to the development of antimicrobial resistance in humans and animals, and there is an urgent need to reduce antimicrobial use in farm animals. Veterinarians are typically responsible for prescribing and overseeing antimicrobial use in animals. A thorough understanding of veterinarians' current prescribing practices and their reasons to prescribe antimicrobials might offer leads for interventions to reduce antimicrobial use in farm animals. This paper presents the results of a qualitative study of factors that influence prescribing behaviour of farm animal veterinarians. Semi-structured interviews with eleven farm animal veterinarians were conducted, which were taped, transcribed and iteratively analysed. This preliminary analysis was further discussed and refined in an expert meeting. A final conceptual model was derived from the analysis and sent to all the respondents for validation. Many conflicting interests are identifiable when it comes to antimicrobial prescribing by farm animal veterinarians. Belief in the professional obligation to alleviate animal suffering, financial dependency on clients, risk avoidance, shortcomings in advisory skills, financial barriers for structural veterinary herd health advisory services, lack of farmers' compliance to veterinary recommendations, public health interests, personal beliefs regarding the veterinary contribution to antimicrobial resistance and major economic powers are all influential determinants in antimicrobial prescribing behaviour of farm animal veterinarians. Interventions to change prescribing behaviour of farm animal veterinarians could address attitudes and advisory skills of veterinarians, as well as provide tools to deal with (perceived) pressure from farmers and advisors to prescribe antimicrobials. Additional (policy) measures could probably support farm animal veterinarians in acting as a more independent animal health consultant.