The U.S. Bureau of Land Management has announced two wild horse fertility control trials will be conducted this summer at a corral facility in Nevada as part of the agency's efforts to control wild-horse populations.
“Wild horses are incredible animals, but they can reproduce at a very high rate on public lands, which creates a host of challenges in arid environments,” BLM Director Tracy Stone-Manning said in the BLM new release on the trials. “The development of humane, safe, and long-lasting fertility control vaccines is critically important as we continue to ramp up our efforts to protect these herds from the effects of wild horse overpopulation, drought, and climate change.”
Scientists associated with Cornell University College of Veterinary Medicine and Northwest Wildlife Conservation Research, a small non-profit research organization, will be conducting a study on whether “SpayVac,” a form of porcine zona pellucida (PZP) vaccine, lasts longer when injected in the neck muscle or the flank.
The second study, headed by USDA's Animal and Plant Health Inspection Service’s National Wildlife Research Center, will test which formulations of the Oocyte Growth Factor vaccine cause long-lasting contraception from a single dose, according to the release.
Groups of vaccinated mares will live in a pen with a stallion to test the vaccine’s effectiveness, BLM reports. Researchers will monitor the mares’ responses to the vaccines and compare them against a control group. Researchers and other personnel will monitor the health and welfare of all the animals. Veterinary care will be available if needed. Independent animal care and the research institutions involved in the study will provide animal welfare oversight, according to the release.
Fertility-control vaccines have been tested in wild horses for decades, the news release states, however most vaccines require more than one treatment and typically last for only a year or two.
The BLM began testing the effectiveness of the OGF vaccine in May 2020. In that study, researchers vaccinated 16 previously gathered mares then put them in a pen with a stallion and the results were compared to a control group. A previous focused on a multi-dose version of the same vaccine.
William Perry Pendley, a previous BLM Deputy Director for Policy and Programs, said in the 2020 release that BLM had sought a long-term vaccine for decades to control the rapid growth of wild horse and burro populations effectively and humanely on public lands. An "all-of-the-above" approach was needed, according to Pendley in 2020, as the overpopulation of wild horses and burros threatened the long-term health of public lands. The start of the trial was an important step forward to developing more effective population management tools to help solve the growing crisis, he said at the time.
