Friends of Animals has won its lawsuit filed against the U.S. Environmental Protection Agency for denying the organization’s May 2015 legal petition asking the agency to consider new scientific evidence demonstrating the need to cancel the registration of the pesticide porcine zona pellucida. The registration for PZP was issued to the Humane Society of the United States in 2012 so it could be used as chemical sterilant to control the population of America’s wild horses and burros.

On Tuesday, U.S. District Court Judge Michael Simon adopted the findings and recommendations outlined by United States Magistrate Judge Patricia Sullivan in October of 2019. You can read those findings here. 

“The EPA will now be required to look at the compelling evidence submitted with our petition concerning the detrimental impacts of the use of the pesticide on wild horses rather than shirking their statutory responsibilities, which is what the agency has been trying to do throughout this process,” said Michael Harris, director of FoA’s Wildlife Law Program. “It was a long, hard fought case but worth the effort. It’s a thrilling victory for the wild horses and those who advocate for their well-being and freedom and a stunning blow to the meat industry and energy interests who want them wiped out.”

Information is now available to the EPA regarding the unintended—and previously undisclosed—side effects on both targeted mares and wild horses in general. It not only shows unreasonable adverse effects, but also indicates the use of PZP on wild horses likely violates the Wild Horse and Burro Act of 1971.

“We fully believe the research is legitimate, and therefore the use of PZP on wild horses is likely illegal under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA),” Harris added.

When the HSUS applied to EPA to register PZP, the organization was so excited that PZP was effective at preventing pregnancy in mares that it failed to evaluate whether the forced drugging of horses could negatively impact individual animals or the herd. Indeed, most of the research submitted by HSUS was published by the late Dr. Jay Kirkpatrick, a veterinarian who manufactured PZP, and who never studied the biological, social and behavioral effects the drug can have on wild horses.

Since EPA originally granted the registration, independent research has been published identifying previously undisclosed effects of PZP on wild horses. Among the findings, it is now known that PZP poses the risk of immediate physical damage to the dosed mares, can increase the mortality rate in foals born to treated mares after the PZP loses its effectiveness, can result in social disruptions among herds with treated mares that can damage long-term herd cohesion that is critical to the health of the animals, and places the wild horses at risk of a genetic bottleneck. Over a decade ago, experts warned that most wild equid populations managed by the BLM are kept at population sizes that are small enough for the loss of genetic variation to be a real concern.

“PZP pushers have coerced the EPA into thinking that wild horses are nuisances and pests that need to be controlled and managed. If the Bureau of Land Management continues its violations against wild horses—roundups and forcibly drugging mares with PZP—we expect wild horses will go extinct on federal public lands,” said Priscilla Feral, president of Friends of Animals. “Anyone supporting those physical assaults is morally bankrupt and undermines the integrity and importance of wild horses. Our definition of wild means no human exploitation and manipulation of free-roaming animals. It’s time to remove the actual culprits of land degradation from herd management areas—cattle and sheep.”

For more about FoA’s wild horse efforts click here.