Abstract

Fatalities have been associated with phocine and canine distemper viruses in marine mammals. While serologic response following distemper vaccination has been documented in Phocidae and Otaridae, it has not been evaluated in walruses (Odobenus rosmarus). The objectives of this study were: 1) to evaluate the intensity and duration of seroconversion in walruses administered a recombinant distemper vaccine, and 2) to report potential clinical adverse effects. Blood samples were acquired with operant conditioning from three walruses under human care, a female and two males, at the caudal gluteal vein. Baseline anti-distemper antibodies serum concentrations were measured using a commercially available seroneutralization test (Cornell University Animal Health Diagnostic Center). Each walrus was administered two 1 mL doses of canarypox-vectored distemper vaccine (Ferret PureVax, Merial Ltd, Duluth, Georgia) three weeks apart in the gluteal muscles. Serial blood samples were performed for the following 12 months or until low titers (<32) were measured. All walruses seroconverted. Medium positive titers (64–128) were detected for 4 to 9.5 months in two of three individuals. Interindividual variability was noted, with one individual displaying only low positive titers. Major swelling occurred at the site of injection after the second injection of primovaccination in all three walruses, and was associated with lameness for a week following injection. Contrary to results reported in Steller sea lions (Eumetopia jubatus), displaying high antibody titers for more than 8 years after administration of a canarypox-vectored distemper vaccine, shorter booster intervals, higher doses or administration of another vaccine may be required in walruses.¹

Acknowledgements

The authors wish to thank the animal health technicians and trainers of the Aquarium du Québec and the residents in Zoological Medicine of the Université de Montréal for their contribution to this project.

Literature Cited

1.  Strobel MM, Haulena M, Rosen DA, Nielsen O. 2019. Serologic response to vaccination with recombinant canine distemper vaccine in steller sea lions (Eumetopias jubatus) over an 8-year period. IAAAM 50th Annual Conference Proceedings, Durban, South Africa.