The Bureau of Land Management (BLM), the agency charged with “managing” America’s wild horses and burros is planning barbaric, archaic, and dangerous sterilization experiments on captured wild mares at its Wild Horse Corral Facility in Hines, Oregon. These experiments have never before been performed on wild horses or, in the case of two of the three proposed procedures, on horses anywhere at all!

Barbaric Procedures Planned for Pregnant Mares

At least 100 mares, 75 of whom will be pregnant, will be subjected to “ovariectomy via colpotomy,” a dangerous procedure in which a veterinarian makes an incision in the mare’s vagina, inserts his arm into the vaginal cavity, manually locates the ovaries and rips them out using an “ecraseur,” a rod-like device with a chain on the end. The painful procedure will subject mares to the risk of infection, hemorrhage and evisceration (intestines coming through the incision), and cause mares in the early to mid-stages of pregnancy to abort their fetuses.


In domestic mares, this procedure is not common, but when performed, requires a post-surgical 4-7 days stall confinement, during which the first 48 hours are spent in crossties to prevent the mare from lying down. No such restraint is possible in wild mares, and the BLM intends to turn them out to corrals after the surgery with open incisions and no restrictions on movement. This fact led the National Research Council (NRC) to conclude that the fatality rate for the BLM’s proposed experiment would be “higher than the one percent reported in the published literature,” which is based on a surgery performed in domestic mares. The NRC a stated that less invasive techniques would be preferable to this procedure in wild mares.

Two less invasive experimental procedures are also proposed that would use endoscopes to achieve sterilization without removal of the ovaries. However, these procedures have never before been done in horses, domestic or wild, and appear to be infeasible for use in wild mares.

It is unconscionable for BLM to proceed with these painful and dangerous experiments that endanger the lives of the un-consenting equine subjects and their unborn foals, particularly when a proven non-invasive and safe fertility control method exists in the readily available PZP birth control vaccine. Instead of wasting millions of tax dollars to fund experiments on inhumane and impractical sterilization experiments, the agency should instead focus resources on vaccinating sufficient numbers of mares with the humane PZP fertility control vaccine, which is documented through 30 years of experience and published science, to be safe, effective, cost-effective and successful in managing wild horse populations.

What You Can Do

The agency is accepting public comments on an Environmental Assessment (EA) and now is the time to voice our united and strong opposition to this outrageous proposal!


Please join the American Wild Horse Preservation Campaign in taking a stand against these dangerous and costly BLM wild horse experiments today. The BLM deliberately avoided public opposition by skipping the scoping stage of this process, so let’s use the EA stage to show the agency just how many citizens and taxpayers oppose these dangerous and costly experiments on our wild mares.  You can take action here.