Fertile Fillies: The Impact of PZP on Wild Horse Populations

Spring has arrived, bringing with it a new wave of wild horse foals. However, the use of equine contraceptives like PZP has sparked a heated debate among activists and organizations.

Editor's Note: Due to delays in administering PZP to the Pine Nut horses, another roundup will occur, resulting in more horses being permanently removed from the range. As noted, "we’ll get a big wave of foals next spring, which sounds cute until you consider the drought." This suggests a lack of understanding about the conditions in the Pine Nut HMA.

By Georgia Fisher, Reno News and Review

Friends of Animals, a Connecticut-based group, halted a scheduled mustang roundup in the Pine Nut Herd Management Area in March. They cite concerns over the use of the contraceptive porcine zona pellucida (PZP), despite endorsements from the Humane Society and collaboration with the American Wild Horse Conservation (formerly American Wild Horse Preservation) to administer it.

“They may want to stick their head in the sand and use this as a fundraising opportunity,” Friends of Animals president Priscilla Feral said in a prepared statement, criticizing the preservation campaign and an affiliated group called Return to Freedom.

The Humane Society disagrees, stating, “Both deer and wild horses treated with PZP actually show comparable or better body condition than females who continue to have offspring. In wild horses, this improvement in condition leads to longer lifespans.”

Friends of Animals reference a 2009 Princeton study that found the contraceptive to be socially disruptive among equines, a significant concern given the importance of herd dynamics. Opponents also highlight genetic research suggesting that thousands of animals are needed in an area to ensure healthy offspring.

BLM horse and burro specialist John Axtell noted that only two mares in the area received the contraceptive this spring. Without intervention, a large wave of foals is expected next spring, which could exacerbate issues during a drought.

“If this is a normal summer, there’s the potential for a lot of horses to die out there if we don’t do anything,” Axtell said. “It’s going to continue to degrade the habitat.”

The Pine Nut roundup was stalled due to an outdated environmental assessment by the BLM. Axtell anticipates the bureau will draft a new one and attempt to gather the horses after their foals mature.

The American Wild Horse Conservation (formerly American Wild Horse Preservation) does not support roundups or many BLM policies but sees contraception differently.

“It happens in a split second,” AWHC spokeswoman Deniz Bolbol said of the darting process, for which she is a trained volunteer. “They don’t even run away. They jolt a little, but they just keep on grazing right in front of you.”

Originally Posted By Reno News and Review