Busting myths about wild horse contraception

Contraceptive fertility control is the only humane, viable approach to managing wild horses

America’s wild horses are trapped in a political crossfire.

Pressure from ranchers and other economic interests fuels the demand for removal of wild horses from public lands, despite the published fact that removals – by any means - increase reproductive success among the horses left behind.

Meanwhile, some horse advocacy groups also fuel roundups by opposing the use of the contraceptive vaccine to slow down horse herd reproduction.

Caught in the middle are the horses, horse supporters, scientists and wildlife managers who understand that immunocontraception works, is safe for horses, and helps reduce the need for inhumane roundups and removals.

The National Academy of Scientists in 2013 advised immunocontraception as a better approach for managing wild horses on federal land. The U.S. Bureau of Land Management uses it in some herd management areas. But this use is opposed by some horse advocates. Misinformation and misunderstanding of immunocontraception abounds.

In the meantime, roundups and removals continue. Horses are chased down by helicopter, stressed and put at risk for injury and death, and are kept in holding pens at taxpayer expense. This unworkable management scheme costs U.S. taxpayers an estimated $75 million annually.

Some key facts:

  • The immunocontraceptive vaccine PZP is a non-hormonal vaccine with a 30-year-plus track record of safe use in wild horses and other species, and is currently being used in more than 30 different wild horse populations, on public land, sanctuaries and tribal lands.
  • PZP is not a commercial product, not patented and not sold at a profit. It is produced and distributed (at a loss) on a non-profit basis by the Science and Conservation Center in Billings, Montana.
  • In addition to wild horses in the U.S. and elsewhere, PZP is used to manage urban deer, bison on Catalina Island, and elephants in more than a dozen African wildlife preserves. It is also used on more than 85 species of zoo animals in 12 different countries.
  • The vaccine doesn’t harm animals and is not permanent. Unless a female horse or other animal receives a booster, PZP wears off after a year or two. It doesn’t pass into the food chain or into the surrounding environment.

Please share this information with your friends to help spread the word. You can learn more about wildlife fertility control in horses and other wildlife via these resources:


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Information: Animal Fertility Control Vaccine
Learn more about managing wildlife with fertility vaccine