Infection prevention and control (IPC) in veterinary medicine is crucial to protect patients, owners, staff, and the public. An IPC programme is recommended for every animal hospital. The objective of this retrospective longitudinal study was to describe the changes in bacterial and multidrug-resistant (MDR) bacterial isolates and self-reported hand hygiene awareness and practices after an IPC programme to assess the long-term effect of this programme in small animal veterinary medicine. The IPC programme was implemented at our veterinary teaching hospital in April 2018, which included the establishment of an infection control task force, regular IPC lectures and poster campaigns, infrastructure improvement, and manual refinement. Laboratory-based surveillance was retrospectively conducted before and after the programme (January 2016–December 2022). Level and slope changes in bacterial isolates were evaluated using interrupted time-series analysis. Self-reported hand hygiene awareness and practices were assessed using an annual questionnaire. Additionally, hygiene product purchases during the study period were investigated. The monthly number of total and MDR bacterial isolates decreased significantly after the programme (MDR level change: −0.426; 95% confidence interval: −0.744, −0.109; P = 0.009; and MDR slope change: −0.035; 95% confidence interval: −0.058, −0.011; P = 0.003). Additionally, awareness of hand hygiene before touching animals improved after the programme. Overall self-reported hand hygiene practices improved, and hygiene product purchases significantly increased. These results suggested that the IPC programme may have long-term effects regarding reducing total and MDR bacterial isolates and improving hand hygiene awareness in veterinary medicine. •Infection prevention and control (IPC) programmes promote IPC like hand hygiene.•The number of bacterial isolates decreased after the IPC programme.•The number of multidrug-resistant bacterial isolates also decreased.•The changes of isolates were minimal after the coronavirus disease 2019 pandemic.•Overall hand hygiene awareness was improved after the IPC programme.