BLM Begins New Fertility Control Trial as Overpopulation of Wild Horses and Burros on Public Lands Reaches New Heights

The Bureau of Land Management has started testing a promising new fertility control vaccine that could help address the growing overpopulation of wild horses on public rangelands. Researchers believe the Oocyte Growth Factor (OGF) vaccine, administered to a captured wild mare through a single dose, may safely prevent pregnancy for up to three years or longer. Following an environmental analysis and final decision record issued last March, testing of the vaccine began May 12 and is taking place in Carson City, Nevada as part of a joint research project between the BLM and the U.S. Department of Agriculture (USDA), Animal and Plant Health Inspection Service’s National Wildlife Research Center. As part of the project, 16 previously gathered wild mares were treated with the fertility control vaccine and will be placed in a pen with a stallion once the vaccine takes effect. Researchers will monitor the mares’ response to the vaccine and compare the results to a control group. The BLM-supported project follows a previous study that safely and effectively tested a multi-dose version of the OGF vaccine in domestic horses. The BLM seeks an effective one-dose version. Though the research is still in its very early phase, if proven viable, the OGF vaccine could help bolster existing methods used by the BLM to manage wild horse populations. The most common fertility control vaccines for wild horses in use today are short-lasting and require near-annual retreatment to remain effective. A single-dose vaccine that can last multiple years, such as the OGF vaccine if proven viable, would provide a number of benefits for BLM, including requiring fewer instances of gathering animals for retreatment or permanent removal...MORE