Rabbit Calicivirus Vaccination

Rabbit calicivirus (RCV) causes a fatal hemorrhagic disease in European rabbits. In Australia, it has decreased the wild population by ≈95% in some areas. Because there is no known treatment and the disease is fatal, it is important to vaccinate pet rabbits. However, because of concerns about potential adverse events, rabbit owners are often hesitant to comply. Published research about RCV pet rabbit vaccination is scarce.

In this retrospective study, the medical records of 9 veterinary hospitals that vaccinated rabbits over a 2-year period were reviewed for cases of RCV vaccine reactions. Review identified 933 vaccination events in 705 rabbits. Adverse events were documented in 17/933 vaccinations, all in different rabbits. The most common (13/17) was irritation (eg, abrasions, scabs, hair loss) at the injection site. Four rabbits were described as having inappetence, GI tract stasis, lethargy, or forelimb lameness. No rabbits died. Side effects were less likely to occur in older rabbits.

Overall, incidence of adverse reactions to vaccination was low (1.8%). The authors concluded that because observed adverse reactions to vaccination were infrequent and generally self-limiting, RCV vaccination benefits outweigh the risks.

RCV is a reportable, fatal hemorrhagic disease that has affected European rabbits in China, Europe, Australia, New Zealand, and Cuba. Although outbreaks have occurred in the United States, the country is considered RCV-free, and US veterinarians do not vaccinate for RCV.

However, with increased world travel, trade, and climate change, diseases are spreading, and RCV could spread to the United States. Therefore, knowledge about how rabbits respond to vaccination is important. In this study, occurrence of adverse events was low, with the majority being local reactions. This information can help clinicians educate clients about the safety of vaccines, especially when managing a highly infectious fatal disease for which prevention is the only treatment. Thankfully, it seems US wildlife species are not susceptible to RCV. This minimizes the risk for the disease becoming endemic if it reaches the United States.—Jennifer Hausmann, DVM, Zoological Medicine Resident, University of Wisconsin School of Veterinary Medicine