THE U.S. Department of Agriculture-Wildlife Services' National Wildlife Research Center (NWRC) announced that the Environmental Protection Agency has granted regulatory approval for the use of GonaCon-Equine immunocontraceptive vaccine in adult female wild or feral horses and burros.
GonaCon was developed by NWRC scientists and is the first single-shot, multiyear wildlife contraceptive for use in mammals, NWRC said.
"Since 2009, GonaCon has been available for use in female white-tailed deer. We are pleased to be able to expand the vaccine's application to include wild horses and burros," NWRC director Larry Clark said. "This non-lethal tool will provide another option to wildlife managers working to reduce overabundant wild horse and burro populations in the U.S."
The Bureau of Land Management (BLM) estimates that about 31,500 wild horses and 5,800 burros are roaming on BLM-managed rangelands in 10 western states, according to the announcement.
Current management options are limited, with the majority of actions involving the removal of horses and burros from the range and either offering them for adoption or holding them in captivity indefinitely.
The GonaCon-Equine vaccine stimulates the production of antibodies that bind to the gonadotropin-releasing hormone (GnRH) in an animal's body. GnRH signals the production of sex hormones; by binding to GnRH, the antibodies reduce GnRH's ability to stimulate the release of these sex hormones. All sexual activity is decreased, and animals remain in a non-reproductive state as long as a sufficient level of antibody activity is present.
USDA said the product can be delivered by hand injection, jab stick or darting.
GonaCon-Equine is registered as a restricted-use pesticide, and all users must be certified pesticide applicators or under their direct supervision. Only certain federal and state agencies responsible for wild or feral horse and burro management, public and private wild horse sanctuaries or people working under their authority can use it.
NWRC is currently manufacturing the vaccine, but Wildlife Services said it is interested in licensing the vaccine to a private manufacturer.
Future NWRC research with GonaCon will likely involve studies to support expanded registration to other species (e.g., prairie dogs and feral dogs) and to aid in preventing the transmission of wildlife diseases.