Antibody response to feline panleukopenia virus vaccination in healthy adult cats

According to prior studies, between 25.0% and 92.8% of adult cats have antibodies against feline panleukopenia virus (FPV) and thus are likely protected against FPV infection. It is, however, unknown how healthy adult cats with different antibody titres react to FPV vaccination in the field. Therefore, the aim of the study was to measure antibody titres in healthy adult cats within a period of 28 days after vaccination against FPV and to evaluate factors that are associated with a lack of adequate response to vaccination. One hundred and twelve healthy adult cats were vaccinated with a vaccine against FPV, feline herpesvirus and feline calicivirus. Antibodies against FPV were determined before vaccination (day 0), on day 7 and day 28 after vaccination by haemagglutination inhibition (HI). A HI titre ⩾1:40 was defined as protective. An adequate response to vaccination was defined as a four-fold titre increase. Uni- and multivariate statistical analysis was used to determine factors associated with an adequate response. Pre-vaccination antibody titres of ⩾1:40 were present in 64.3% (72/112; 95% confidence interval [CI] 55.1–72.6). Only 47.3% (53/112; 95% CI 37.8–57.0) of cats had an adequate response to vaccination. Factors associated with an adequate response to vaccination were lack of previous vaccination (odds ratio [OR] 15.58; 95% CI 1.4–179.1; P = 0.035), lack of antibodies (⩾1:40) prior to vaccination (OR 23.10; 95% CI 5.4–98.8; P <0.001) and breed (domestic shorthair cats; OR 7.40; 95% CI 1.4–38.4; P = 0.017). As none of the cats with high pre-vaccination antibody titres (⩾1:160) had an at least four-fold increase in FPV antibody titres, measurement of antibodies rather than regular revaccinations should be performed. Thus, evaluation of FPV antibody titre in cats with previous vaccinations against FPV are recommended prior to revaccination.