Veterinarians: Sign-on to Stop Mass Ovariectomy Surgeries on Wild Mares

September 30, 2019

Dear Colleagues,

I am writing you today to ask for your support in opposing the Bureau of Land Management’s (BLM) plan to perform the outdated and controversial ovariectomy via colpotomy surgical procedure on wild mares. I hope you will join me in this letter to Interior Secretary Bernhardt requesting that the BLM drop all plans to perform these inappropriate surgical sterilizations on federally protected wild horses.

As veterinary medical practitioners, we have an ethical obligation to comment on the inadvisable and inhumane use of ovariectomy by colpotomy to sterilize wild horses.

While many veterinarians may not be familiar with the challenges surrounding the management of wild horses and burros on federal lands, we’ve all no doubt seen a headline about overpopulation of wild horses in Western states. The reality is that the numbers (including what constitutes appropriate population levels) are not clear, and political issues, as well as competing stakeholder interests, make the management of our nation’s wild horses a far from straightforward or simple issue. But in the context of reducing the numbers, certain proposals besides roundups have been discussed, and in the past few years, the BLM has presented an outdated veterinary surgery as a solution for how to “manage” the wild horses the agency is charged under federal law to protect from harassment, harm, and death.

The proposed study of ovariectomy via colpotomy, which involves surgically spaying wild mares and then releasing them back into the wild, poses a number of problems. The agency’s stated experimental goal is to quantify the rate of mortality and morbidity from conducting this surgical procedure on wild horses. The BLM explained the procedure in its environmental assessment analyzing the study of ovariectomy via colpotomy on 100 mares.

The surgical procedure would involve making an incision, approximately 1–3 centimeters long, in the anterior-dorsal-lateral vagina. Both ovaries are accessed through this one incision. The incision would be enlarged with blunt dissection to perforate the peritoneum and allow the surgeon’s hand to enter the abdomen. This method separates rather than transects the vaginal muscle fibers so the incision decreases in length when the tissues contract after the surgery. The ovary and associated mesovarium are isolated by direct manual palpation and local anesthesia (5 ml 5% bupivacaine and 5 ml 2% lidocaine) is injected into each ovarian pedicle. This combination was selected to provide rapid onset (lidocaine) and extended duration (bupivacaine) of effect, reducing pain associated with removal of the ovaries. The surgeon would add epinephrine to the lidocaine/bupivacaine anesthetic mixture injected into the ovarian pedicle to constrict blood vessels. This may reduce the risk of hemorrhage at the surgical site, and by reducing blood flow at the site of injection the local anesthesia should stay longer at the surgical site. Reducing blood flow at the site of the injection of the anesthetic mixture should prolong the effect of the local anesthetic at the surgical site and may reduce the risk of hemorrhage. The anesthetic preparation would be 1 ml of 1:1000 epinephrine for injection added to 100ml of the lidocaine/bupivacaine mixture. The ovarian pedicle would be transected with a chain ecraseur.

Veterinarians have already spoken out about the following risks associated with the procedure:

• Impacts on physiology due to reduction of estrus and alteration of hormones.
• Impacts on the wild behaviors of individual horses and herds.
• Risk of infection under conditions that may not be sterile.
• Risk of harm due to sedation and restraint in wild horses.
• Risks of hemorrhage, evisceration, colic and infection due to inability to provide the required post-operative care.
• The risk of postoperative pain in these mares and the BLM’s inability to provide adequate post-operative pain relief.
• The feasibility of the proposed procedures for use on the range, including cost, complications presented by the fact that most wild mares immediately coming off the range will be in some stage of pregnancy, and the lack of a sterile environment for surgery.

I urge my fellow veterinarians to review the proposed surgery, the lack of aftercare, the lack of adequate pain management, and the lack of sterility and join me in signing on to the letter which you can view here. The risks of this procedure far outweigh the benefits, particularly when alternatives, such as the PZP birth control vaccine, are available for humane wild horse management.

Sincerely,

Pamela Corey, DVM