This talk will review recent updates to antibiotic susceptibility testing breakpoints for companion animals, reflecting new insights into drug delivery to infection sites. These updates, particularly for chloramphenicol and fluoroquinolones, have major clinical implications. With the new breakpoints, many pathogens previously classified as susceptible will now be reported as resistant, significantly impacting prescribing practices. In addition to discussing these important changes, the presentation will highlight common pitfalls in antibiotic susceptibility testing and provide practical tips for improving the use of these tests. By adopting these updated practices, veterinarians can enhance their clinical decision-making and antibiotic prescribing, ultimately leading to improved patient outcomes.