This study retrospectively reviewed serologic data for rabies-neutralizing antibodies in 662 young dogs to evaluate whether certain variables (eg, signalment, number of vaccinations, vaccine brand and multivalence, time interval between the most recent vaccination and blood sampling) affected dogs’ ability to achieve acceptable rabies titers. Dogs that had been vaccinated twice before 12 months of age were found to have significantly higher antibody titers than those vaccinated once; those vaccinated with monovalent vaccines were more likely to achieve an acceptable titer than those vaccinated with polyvalent vaccines. Dogs vaccinated after 3 to 6 months of age had higher antibody titers than those vaccinated earlier.