Antimicrobial use (AMU) in humans and animals facilitates the emergence of antimicrobial resistance (AMR). With increasing AMR being recognised as a major global threat for public health, responsible AMU is strongly advocated in both human and veterinary medicine. Knowledge on factors influencing antimicrobial prescribing behaviour of companion animal veterinarians is needed to promote responsible AMU in companion animals and to improve compliance with current legislation and guidelines. The present study aimed to quantitively investigate attitudes and perceptions of companion animal veterinarians towards AMU and AMR and to identify associations with demographic characteristics as possible explanatory variables. A self-administered questionnaire was developed based upon an earlier qualitative interview study, and 1608 potential participants (i.e. practising companion animal veterinarians) were invited. The questionnaire included questions addressing general descriptives of the respondents and questions with 6-point Likert scale statements, to assess attitudes towards AMU, AMR, factors influencing antimicrobial prescribing, and possible options to support responsible AMU. The response rate was 32% (22% when complete questionnaires considered). Categorical Principal Component Analysis (CATPCA) was conducted on 76 Likert scale questions. This resulted in a final model with 37 questions explaining 38.7% of the variance of the question scores, with three underlying dimensions ("attitudinal profiles"). Additionally, general descriptives were added to the CATPCA as possible explanatory variables. The first dimension, related to "social responsibility" was positively associated with veterinarians working in clinics dedicated to companion animals, with veterinarians working in a referral clinic, and with more experienced veterinarians. The second dimension was related to "scepticism", which was positively associated with being a male veterinarian and with more experienced veterinarians. The third dimension was related to "risk avoidance", especially regarding surgical procedures, and was negatively associated with veterinarians working in clinics in urban areas and with veterinarians working part-time. Antimicrobial prescribing behaviour was self-reported to be well considered, and respondents did not see economic drivers as important influencing factors. The unwillingness of owners and financial constraints were perceived as important barriers for performing further diagnostics. To improve AMU, a multifaceted approach, taking differences between companion animal veterinarians (e.g., in experience and gender) and differences in work situation (e.g., full-time versus part-time) into account, should be directed at companion animal veterinarians and owners. Moreover, a joint and comprehensive effort of several stakeholders, like veterinary nurses, guideline developers, pharmaceutical industry, and providers of diagnostics, is needed to optimise AMU in companion animals.