Serological Response to Canine Distemper Vaccination in Wild Caught Raccoons (Procyon lotor)

Authors

Molly R. Selleck, United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, ColoradoFollow
Shylo R. Johnson, United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, ColoradoFollow
Amy T. Gilbert, United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, ColoradoFollow

Document Type

Article

Date of this Version

2024

Citation

Journal of Zoo and Wildlife Medicine (2024) 55(2): 462-465

doi: 10.1638/2023-0078

Comments

United States government work

Abstract

Canine distemper virus (CDV) is a well-known RNA virus that affects domestic dogs and all families of wild terrestrial carnivores. Spillover infections from wildlife to domestic animals are mitigated by preventive vaccination, but there is limited information on the off-label use of veterinary vaccines for wildlife like raccoons (Procyon lotor). Twenty wild-caught raccoons were inoculated with a commercial recombinant DNA canarypox-vectored CDV vaccine, applying a regimen of two serial doses by SC route with an interval of 25-28 days between doses. The CDV serum virus neutralizing antibody (VNA) baseline titers and the postvaccination titers were measured at fixed time points. Forty percent (8/20) of the wild-caught raccoons had CDV VNA titers of 1:8 or greater upon intake, and all but a single individual were juvenile animals. Approximately one month following the first vaccine dose, 8% (1/12) of raccoons seronegative at baseline had serum CDV VNA titers of 1:24 or greater. Approximately one month following the booster vaccine dose, 67% (8/12) of raccoons seronegative at baseline had serum CDV VNA titers of 1:24 or greater. Among raccoons with CDV VNA titers greater than or equal to 1:8 at baseline, 13% (1/8) demonstrated a fourfold or greater rise in titer one month after the first vaccine dose, whereas 38% (3/8) reached the same threshold one month after the booster dose. The presence of naturally acquired CDV VNA in juvenile raccoons at the time of vaccination may have interfered with the humoral VNA response. A regimen of at least two serially administered SC vaccine doses may be immunogenic for raccoons, but further investigation of alternative routes, regimens, and CDV vaccine products is also warranted for this species.