A prospective study was performed to explore the prescription habits in fourteen first-line,small animal practices during first consultations of cats and dogs. Consultations one monthprior to the implementation of antimicrobial use guidelines and at least 20 days thereafter wereexamined. Differences in the proportion of consultations during which antimicrobials wereprescribed, were assessed. Additionally, changes in the choice of active substance were criticallyevaluated against the introduced antimicrobial use guidelines. The proportion of consultationswhere antimicrobials were prescribed decreased in cats and dogs (both –12%) after theintroduction of the antimicrobial use guidelines. There was an increase of consultations of cats(+13%) and dogs (+10%) where veterinarians handled according to those guidelines. However,an increase in the prescription of third-choice antimicrobials and highest priority criticallyimportant antimicrobials was noticed both in cats (+8% and +12%, respectively) and dogs (both+5%). This unexpected increase invites to create extra awareness amongst prescribers.