IM03 - Immune Response of Cats After Simultaneous versus Separate Vaccination Against Rabies and Feline Leukemia Virus

Abstract: Background – To minimize the risk of feline injection site-associated sarcomas, cats should be vaccinated with non-adjuvanted feline leukemia virus (FeLV) and rabies vector vaccines, which are currently not licensed for simultaneous use and have to be administered on separate visits.

Hypothesis – The aim of the study was to investigate the immune response of cats after vaccination against rabies and FeLV at simultaneous versus separate visits using canarypox-vectored vaccines.

Animals – 106 healthy, FeLV antigen-negative, client-owned kittens (8-12 weeks) were included.

Methods – In this prospective randomized study, all cats received primary vaccinations against rabies (day 0) and FeLV (day 28, 56). After one year, the study group (n=52) received booster vaccinations against rabies and FeLV simultaneously (day 364). The control group (n=54) received booster vaccinations against rabies (day 364) and FeLV (day 392) separately (4 weeks apart). Anti-rabies antibodies were determined by fluorescent neutralization assay (days 28, 364, 392) and significant differences in anti-rabies antibodies between both groups were determined by Mann-Whitney U test.

Results – Four weeks after the one-year booster vaccination against rabies, all cats had anti-rabies antibodies (≥0.5 IU/ml), and there was no significant difference (p=0.141) in the median titer between the study group (14.30 IU/mL) and the control group (21.39 IU/mL).

Conclusions and clinical importance – According to the World Health Organization and the World Organization for Animal Health, anti-rabies antibodies ≥0.5 IU/ml indicate protection against rabies. Simultaneous administration of FeLV and rabies vector vaccines does not interfere with the development of anti-rabies antibodies.