Adverse reactions in a population of Sydney pet rabbits vaccinated against rabbit calicivirus

To determine the general clinical presentation and incidence of adverse reactions to Cylap® RCD vaccinations, of a nature serious enough for veterinary attention, in a Sydney population of pet rabbits.

A retrospective survey using hospital databases.

Nine veterinary hospitals in Sydney participated in a database search for the number of rabbits vaccinated within a 2-year period. The hospitals involved had an identified interest in rabbit medicine and included general, specialist and teaching hospitals. Details of the rabbit, vaccination event and any possible reaction were collected and analysed.

Of 933 events recorded in 705 rabbits, 17 (1.8%) adverse reactions were observed. Of the adverse events, local injection site reactions (alopecia, abrasions and scabbing) were most common. Other reactions, including systemic signs of gastrointestinal tract stasis, lethargy and forelimb lameness, were also documented. Overall, rabbits presented for vaccination were mostly male (57.7%) and desexed (71.3%), with an average age of 28.1 months (median 19.0, range 1.4-149.8 months) and an average weight at first vaccination of 2.12 kg (median 2.08 kg, range 0.18-5.6 kg). A significant association between increasing age and decreased incidence of adverse events was demonstrated (P value, 0.038).

The benefits of vaccination against RCV outweigh the risks of an adverse reaction occurring. Data from this study show that adverse reactions occur infrequently, are generally mild and self-resolving, and decrease in incidence with increasing age. These results are similar to previous field research on wild rabbit colonies and reports from government and industry.