Concerns about antimicrobial resistance have recently prompted a reassessment of antimicrobial use by veterinarians. The FDA Center for Veterinary Medicine has added “impact on antimicrobial resistance” to a list of post-marketing surveillance requirements for new antimicrobials. The primary focus has been food animals because of a concern that resistant microorganisms may (and probably do) contaminate the food supply. Companion animal practitioners should anticipate that attention will also be focused on their practices. Even medical doctors have begun to alter antimicrobial prescribing practices.