ObjectivesTo compare morbidity, mortality, and cost of anti-microbial susceptible (AMS) and anti-microbial resistant (AMR) surgical site infections (SSIs). MethodsClinical records from 2017-2022 were retrospectively obtained from canine and feline patients undergoing a surgical procedure at a single referral hospital. Data collected include patient signalment, surgical procedure and duration, development or otherwise of a SSI (including information pertaining to AMS and AMR SSIs), patient survival or last to follow-up (days), days hospitalized, number of revision procedures required, and final medical bill following patient discharge or death (in £). ResultsA total of 431 patients were included in this study. Following surgery, 340 patients did not develop an SSI (Group 1), 61 developed an AMS SSI (Group 2), and 30 developed an AMR SSI (Group 3). The median final medical bill was £3401, £3884, and £9235 for Groups 1, 2, and 3 respectively (p<0.000). Patients were hospitalized for a median of 3, 3, and 4.5 days in Groups 1, 2, and 3 respectively (p=0.006). Patients in Groups 1, 2, and 3 required a median of 0, 0, and 0.5 revision procedures respectively (p<0.000). Survival for patients in Groups 1, 2, and 3 was 312/340 (92%), 56/61 (92%), and 27/30 (90%) (p = 0.665).