SERUM ANTIBODY RESPONSE TO RABIES VACCINATION IN NORTHERN SEA OTTERS (ENYDRA LUTRIS KENYONI)

While rabies has not been reported in northern sea otters (Enydra lutris kenyoni), it is an infection with severe implications. The World Organization for Animal Health considers a serum titer of at least 0.5 IU/ml as adequate when importing vaccinated domesticated animals into rabies-free areas, a standard often used for zoological species. A few facilities have vaccinated sea otters against rabies, but titers were not analyzed. Production of serum neutralizing antibodies to rabies was evaluated following vaccination of 15 northern sea otters from the Alaska SeaLife Center and the Minnesota Zoo using the rapid fluorescent focus inhibition test. No animals had measurable titers prior to vaccination, and all 15 animals demonstrated antibody production post-vaccination. Titers were evaluated at different intervals (30-834 days) post-vaccination and were found at or above 0.5 IU/ml in 10/10 otters at approximately one month, 3/3 at two months, 6/7 at three months, 1/2 at five months, and 2/6 at 6-13 months. Three animals received a booster vaccination one year post initial vaccination, resulting in increased titers in all three one year later. No adverse reactions to vaccination were noted. If the prevailing epidemiological landscape deems rabies to be a concern, booster vaccinations could be considered after 3-4 months to increase the likelihood of adequate protection.