The goal of this study* was to evaluate the antibody response in healthy adult cats within 28 days of feline panleukopenia virus (FPV) vaccination and evaluate factors associated with adequate antibody response. Results show that 64.3% of 112 cats had antibody titers of ≥1:40 on day 0 and therefore were likely protected against FPV prior to vaccination. An adequate response to vaccination, defined as a 4-fold titer increase, was found in 48.3% of cats. Adequate vaccination response was associated with a lack of previous vaccination, lower day 0 antibody titer (<1:40), and the domestic shorthair breed. Because cats with higher prevaccination titers (ie, ≥1:40) had inadequate antibody responses to revaccination, the authors recommend measuring FPV antibody titers prior to vaccination.