New Initiative to Protect Horses in Eastern Kentucky
We’re thrilled to share a major milestone that the Kentucky Humane Society’s Equine C.A.R.E. team has been leading for free-roaming horses in Eastern Kentucky. In 2025, KHS launched a proactive, humane fertility control program in Magoffin County using Porcine Zona Pellucida (PZP)—a safe, effective contraceptive vaccine that helps stabilize wild horse populations without harming the horses.
For more than two decades, abandoned domestic horses have formed unmanaged herds on former mine sites throughout the Appalachian region. These horses are a beloved part of the landscape, but unchecked reproduction has led to overcrowding, food shortages, roadway hazards and environmental damage.
Traditional methods, such as rescue and rehoming, can’t keep up with the growing population. PZP changes that.
For over 20 years, PZP has been used successfully in mustangs, urban deer populations and zoo animals, offering a 90%+ effectiveness rate in preventing pregnancy. It’s reversible, non-hormonal and does not cause permanent sterility. By using PZP and reducing the number of foals born each year, KHS can help herds remain healthy and sustainable in their environment.
This new tool works hand-in-hand with our other ongoing efforts in Appalachia, which include rescuing and rehabilitating at-risk horses and providing hay and salt to herds in nutrient-sparse areas. Since 2015, KHS has rehomed more than 200 formerly free-roaming horses, but with an estimated 1,000+ horses remaining in the region, PZP is essential to truly getting ahead of the problem.
The introduction of PZP is a game-changer, allowing KHS to shift from a reactive approach—intervening only in crisis situations—to a proactive strategy that prevents overpopulation before it becomes critical.
We estimate that it will take at least three years to see a significant reduction in herd numbers. Since PZP does not affect already-pregnant mares, foals will still be born in 2026. However, vaccinating mares in 2026 will prevent births in 2027 and beyond, leading to a sustainable and humane solution for managing free-roaming horse populations in eastern Kentucky.
This is a historic step that will improve herd health and protect Kentucky’s mountain landscapes. We look forward to sharing more about this humane, innovative solution with you as we see its impact grow.
