American Wild Horse Conservation Statement on Sterilization of Jackson Mountains Wild Horses

American Wild Horse Conservation strongly opposes the Bureau of Land Management’s plan to permanently sterilize wild horses as part of its long-term management strategy for Nevada’s Jackson Mountains Herd Management Area.

The Herd Management Area Plan (HMAP) would continue to manage the Jackson Mountains herd at an Appropriate Management Level (AML) of just 130 to 217 wild horses across nearly 265,000 acres, while authorizing removals, a male-skewed sex ratio, and the release of sterilized mares and males (geldings) to maintain the population within that narrow range. Rather than addressing whether such a low AML is appropriate for the long-term health and genetic viability of the herd, the BLM proposes increasingly invasive measures to keep the population within those artificially low limits.

Of particular concern is the plan’s incorporation of permanent sterilization of both mares and stallions.

For mares, the BLM’s own environmental analysis describes so-called “minimally invasive” procedures in which a mare would be restrained standing in a padded hydraulic chute while a veterinary team passes an endoscope through the vagina and cervix and into the uterus. The uterus would then be partially inflated with air so the veterinarian can visualize the openings to the oviducts. Under one procedure, a catheter would be guided to each oviduct and medical-grade cyanoacrylate surgical glue (hot glue) injected into it, creating a permanent blockage. Under another, a laser would apply heat to the oviductal opening, producing an inflammatory reaction and scar tissue intended to permanently seal it. The EA acknowledges that the procedures can cause abdominal cramping, inflammation and irritation, and provides for sedation, pain medication and post-procedure veterinary monitoring.

For stallions, sterilization means surgical castration. According to the BLM’s own description, a stallion would be sedated and placed under general anesthesia, brought to the ground and positioned on his side or back, with ropes used to restrain one or more limbs. The veterinarian would then make an incision in the scrotum over each testicle and surgically remove both testicles, leaving the incisions open to drain. BLM acknowledges potential complications including bleeding, swelling, inflammation, infection, peritonitis, penile damage, excessive hemorrhage and eventration, a potentially life-threatening condition in which abdominal tissue or intestine protrudes through the surgical opening. The gelded stallions could then be returned to the range within 30 days.

These procedures are permanent and irreversible. Once a mare’s reproductive tract has been permanently blocked or a stallion’s testicles have been surgically removed, that horse can never reproduce again. Each sterilized animal is permanently removed from the Jackson Mountains herd’s reproductive population and can never again contribute its genes to future generations. That irreversible loss is particularly concerning when the BLM already intends to manage this herd at an extremely low population level.

Equine geneticist Dr. E. Gus Cothran has recommended maintaining wild horse populations at approximately 150 to 200 breeding-age animals to preserve genetic diversity over time. BLM’s proposed AML of just 130 to 217 total horses falls perilously close to, and at its lower end below, that threshold even before the agency permanently removes sterilized mares and geldings from the herd’s breeding population.

Permanent sterilization is also unnecessary when proven, humane and reversible fertility-control alternatives are available. PZP immunocontraception offers the BLM a proven way to moderate population growth without permanently eliminating a mare’s ability to reproduce. A sustained PZP program would preserve management flexibility while allowing the agency to protect the herd’s genetic viability and natural social dynamics. Unlike sterilization, reversible fertility control leaves open the ability of individual animals to reproduce in the future when herd demographics, genetic considerations or changing range conditions warrant it.

The Wild Free-Roaming Horses and Burros Act requires the BLM to protect and humanely manage these federally protected animals. That obligation should lead the agency toward humane, science-based and reversible management, not irreversible reproductive manipulation designed to maintain an artificially low population ceiling.

American Wild Horse Conservation raised these concerns directly with the BLM in comments submitted on the Jackson Mountains HMAP. AWHC specifically opposed the proposal to manage a substantial portion of this already small herd as non-reproducing animals, noting that BLM guidance contemplates the use of non-reproducing horses in HMAs with large AMLs, a description that plainly does not fit Jackson Mountains. We also opposed permanent surgical sterilization as invasive and irreversible, particularly given the welfare risks associated with surgery and the limitations on post-operative monitoring once horses are returned to the range. AWHC urged the BLM instead to expand the use of humane, reversible PZP fertility control while preserving natural herd structure and maintaining a sufficiently large breeding population to protect the herd’s long-term genetic viability.

AWHC calls on the BLM to abandon permanent sterilization in the Jackson Mountains HMA, reevaluate an AML of only 130 to 217 horses across nearly 265,000 acres, and implement a robust, sustained PZP fertility-control program as the foundation of long-term population management. The goal of federal wild horse management should be to preserve healthy, genetically viable, naturally behaving herds on the range for generations to come. Once the BLM sterilizes a wild horse, that animal’s contribution to the herd’s genetic future is lost forever.

For questions or further information, please contact Scott Beckstead, Government Relations and Policy Director, at 541-530-3460.