Injection-site reactions in wild horses (Equus caballus) receiving an immunocontraceptive vaccine

Product Type: Scientific Investigations Report

Year: 2009

Author(s): Roelle, J.E. and J.I. Ransom

Suggested Citation:
Roelle, J.E. and J.I. Ransom. 2009. Injection-site reactions in wild horses (Equus caballus) receiving an immunocontraceptive vaccine: U.S. Geological Survey Scientific Investigations Report 2009-5038. 15 p.

Abstract

The U.S. Geological Survey and the Bureau of Land Management are conducting research on the efficacy of the immunocontraceptive agent porcine zona pellucida (PZP) in reducing fertility of wild horses (Equus caballus). As an antigen, PZP stimulates antibody production when injected into many mammalian species. These antibodies bind to the external surface of the ovum, preventing fertilization. By itself, PZP is only weakly immunogenic and is therefore delivered with an adjuvant, most commonly one of the Freund adjuvants, designed to further stimulate antibody production. Freund’s complete adjuvant (FCA) in particular is known to be very effective, but may also be associated with undesirable side effects such as formation of abscesses at injection sites. Such reactions may be exacerbated when accompanied by the additional trauma of a remotely delivered dart. Because horses in our three study herds were individually identifiable by color markings and harem association, we were able to monitor mares for injection-site reactions (abscesses, nodules, swelling, and stiffness) following inoculation with PZP...