Why We Don’t Support Surgical Spaying of Wild Mares

Any day now, the Bureau of Land Management (BLM) will announce its decision on how it will proceed with the controversial surgical sterilization (spay)  experiments it plans to perform on captive wild mares at the Hines corrals in Burns, Oregon. Before that announcement is made, we would like to make it very clear why we do not support this procedure. 

It’s Risky and Invasive

In the procedure, ovariectomy via colpotomy, a veterinarian blindly sticks his hand and arm into a female horse’s abdomen through an incision in the vaginal wall. Then, using a tool with a chain on the end, he manually twists and severs the ovaries bringing them out through the vagina. This is all done without proper pain management.

Warning: Due to the graphic nature viewer discretion is advised.

The procedure subjects wild horses to risk of death from bleeding, infection, or evisceration (intestines protruding through the incision).

Eric Davis, DVM, MS, DACVS, DACVIM, a staff member of UC Davis School of Veterinary Medicine, noted the following risks in a conversation with American Wild Horse Campaign (AWHC) and documented in the organizations public comments:

“The particular complications of the described technique of colpotomy stem from the fact that the procedure is done by palpation only (“blind”) and that the abdomen is left open for the vaginal wall to heal by second intention. When entering the abdomen through the vaginal wall or when manipulating the hemostatic and cutting device (ecraseur) to the ovary, by feel alone, it is possible to lacerate the bowel, causing spillage of gut contents into the abdomen. This would be a terminal event in a wild horse, with even small amounts of abdominal contamination would lead to fatal and painful peritonitis. Another consideration is the possibility of life threatening hemorrhage, as the ecraseur crushes the ovarian vasculature as it cuts. This can be very effective, but without a way to observe the ovarian pedicle, there is no way for the surgeon to be sure that hemorrhage has been controlled and no way to treat serious bleeding if it arises.

While the incision in the vaginal wall is relatively small, it has to be big enough for the surgeon’s arm to pass. As this incision would be very difficult to close with suture, it is left open to heal on its own. While the vaginal wall and mucosa are well vascularized and heal rapidly, for some time after the end of the surgery there is an open hole in the abdominal wall in which small intestine can become entrapped. Again, in a wild mare this would be virtually untreatable and would lead to a very painful death. Surgeons often restrict the exercise of mares after colpotomy, putting them in “tie stalls”. This would be unfeasible in wild horses.”

Scientists have warned against it. In 2013, the National Academy of Sciences (NAS), the nation’s leading scientific body stated in its report to BLM: 

“The possibility that ovariectomy may be followed by prolonged bleeding or peritoneal infection makes it inadvisable for field application.”

Similarly, in 2015, a research review panel of the NAS reviewed BLM’s substantially similar ovariectomy via colpotomy research proposal and warned that conduct of the procedure on wild (vs. domestic) horses could cause the “mortality rate to be higher than the 1% reported in the published literature” and stated that proposals for less invasive sterilization methods “would be safer – with less risk of hemorrhage and evisceration – and probably less painful.”

Veterinarians denounce it. In its public comments on the Environment Assessment addressed to the BLM, the AWHC interviewed several prestigious veterinarian professionals. 

Expert equine veterinarian Dr. Don Moore stated in correspondence with the organization that many professional veterinarians would not even consider ovariectomy via colpotomy as an option.

“In private practice, colpotomy is considered an inferior procedure with likelihood of post-surgical infections and complications especially in unsterile conditions. Post-operative care usually lasts several days to weeks and mares are in most cases monitored in box stalls or cross ties, which cannot be accomplished with wild mares.

Any veterinarian(s) who would perform these experiments is in violation of the oath taken as a graduating veterinarian, ‘above all else, do no harm.’ If a veterinarian in private practice performed these procedures in the manner described in [the EA], they would most certainly be reported to and disciplined by the regulatory board of that state. Disciplined would likely mean suspension of that veterinarian’s license to practice in that state.”

Wild Mares Cannot Be Given Proper Post-Operative Care

In domestic mares, the proposed procedure is not common, but when performed, requires a post-surgical 4-7 days stall confinement, during which the first 48 hours are generally spent in cross-ties to prevent the mare from lying down. Careful post-operative monitoring, antibiotics and pain relief (morphine) epidurals are also necessary.

Wild mares cannot be given necessary post-operative care. The BLM intends to turn them out to corrals after the surgery with open incisions, no restrictions on movement, no close monitoring for hemorrhage or evisceration and no adequate post-surgical pain relief or antibiotic treatment.

This lack of any credible post-operative care plan or procedure is itself a source of controversy and also may violate the Animal Welfare Act.

Dr. Robin Kelly, who has 36 years of veterinary experience and has actually performed reproductive surgery on wild horses shared her concerns about the BLM’s inability to provide post-operative care to wild mares who will be ovariectomized:

“The postoperative care/management proposed for these [BLM] mares is minimal compared to significant post-operative recommendations for domesticated mares. These recommendations include keeping mares tied in a tie stall/tie line to prevent them from laying down/rolling to reduce risk of postoperative hemorrhage or herniation of bowel thru the vaginal incisions that must be left open for second intention healing. These measures are advised since excessive post-operative hemorrhage or herniation of bowel thru the vaginal incisions would not be survivable.

Domesticated mares would be treated with a more aggressive antibiotic choice for 7-10 days post operatively (monitoring daily for complications). Insufficient anti-microbials could result in peritonitis (also likely not survivable). . . . The wild mares will not be provided with post-surgical pain relief, according to the study description, and presumably [will be] turned out in a communal paddock with no restraint.”

Further, the mares will be subjected to this surgery without, as mentioned above, proper pain management used in a controlled veterinary setting for domestic mares. 

Dr. Pamela Corey, who also has decades of related experience, describes the inadequate protocol that the BLM plans to follow.

  • The anesthetic protocol includes ketamine, a dissociative anesthetic that can cause the horse to lose consciousness. The horses will be kept in the standing position during the surgery. Risks to horse and human handler exist if a horse collapses in the stocks.

  • One dose of antibiotic (4-day duration) and a NSAID will be given before the mare is released to a pen for observation. It is a known effect of flunixin (Banamine) that it may mask pain. Repeated dosing can cause harm to other organs (stomach, kidneys) and may hide more serious problems in the animal. Some post op problems that may be masked for a prolonged period of time by repeated use of flunixin can ultimately end in euthanasia. This type of post op “care” is considered and termed “herd management” as opposed to individualized medical monitoring. In unhandled horses this would be viewed as leading to substandard welfare outcomes because the individual may not receive sufficient or appropriate pain management.

  • The use of a surgical incision and visceral manipulation including ecraseur use will cause pain. The use of anesthesia including detomidine and ketamine directly negates any assumption that the mares will only experience slight pain or distress.

Sterilization will take the wild out of wild horses

Sterilizing wild horses will destroy production of the reproductive hormones that drive natural behaviors. These natural behaviors distinguish wild horses from domestic horses, are central to their complex social dynamics and help them survive in their rugged high desert homes.

In 2013, the NAS reported that surgical sterilization on wild horses and burros would result in a loss of behaviors necessary for maintenance of social organization, band integrity, and expression of a natural behavior repertoire.

Dr. Allen T. Rutberg, a faculty member at the Tufts/Cummings School of Veterinary Medicine and a wildlife biologist and researcher who has extensively studied wild horse behavior, echoed the NAS, describing the detrimental effects of sterilization on the natural free-roaming and social behaviors of our wild herds.

“Wild horses typically live in reproductive bands consisting of adult mares, their dependent offspring, and one or more stallions who[se] lives revolve around trying to protect mares from harassment by other stallions and securing exclusive reproductive access to the mares for themselves; ...[m]ares, meanwhile, simultaneously bond to one another and compete with each other for access to water, food, and other resources for themselves and their foals. Neither geldings nor spayed mares participate in these fundamental processes of wild horse behavior.”

Find out who’s behind spaying wild horses

There is no reputable animal welfare organization that supports this brutal procedure. By contrast, Protect the Harvest, a lobbying group for the agriculture and livestock industry is leading the charge as a proponent of this plan.

Protect the Harvest was formed as a direct opposition to what the organization calls “animal rights groups”. It was founded by Forest Lucas, an oil executive, to oppose even basic farm regulations, promote horse slaughter and lobby against animal welfare legislation like preventing cruelty to dogs in puppy mills. 

Three years ago, Protect the Harvest set its sights on helping the BLM to promote the ovariectomy procedures. 

Protect the Harvest created a division--billed as the “Wild Spayed Filly Futurity”, within the popular western horse event, the Reno Snaffle Bit Futurity.  The organization put approximately twelve, 3-year-old fillys through the painful surgeries behind closed doors. Then, they were purchased by trainers and perversely paraded around to further their political agenda: to reduce America’s federally-protected wild horse and burro herds through mass roundup, slaughter and sterilization.