Standing Ovariectomy in Mares Using a Transvaginal Natural Orifice Transluminal Endoscopic Surgery (NOTES®) Approach


  • Karine Pader DVM,

  • Timothy B. Lescun BVSc, MS, Diplomate ACVS,

  • Lynetta J. Freeman DVM, MS, Diplomate ACVS

    Corresponding author
    • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN
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  • Presented in part at the ACVS Symposium, Washington DC, October 2009.

Corresponding Author

Lynetta J. Freeman, DVM, MS, Diplomate ACVS, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, 625 Harrison Street, West Lafayette, IN 47907




To develop and assess the feasibility of standing transvaginal Natural Orifice Transluminal Endoscopic Surgery (NOTES®) ovariectomy in the mare.

Study Design

Descriptive study.


Mares (n=10).


The technique was developed in 6 mares and then evaluated in a short-term study in 4 mares. Abdominal access was developed using controlled access vaginal cannula placement under endoscopic guidance. With viewing provided by a flexible endoscope, hemostasis, and transection of ovarian pedicles was performed using a customized bipolar vessel-sealing device. The ovaries were retrieved and the colpotomy was sutured. Surgical time, intra-, and postoperative complications were recorded. Necropsy was performed immediately after surgery in 6 mares and 15 days after surgery in 4 mares to assess short-term complications.


After the instruments and techniques were developed, transvaginal NOTES® ovariectomy was successfully performed. Analgesia during the procedure was adequate in all cases. The visual field provided by the endoscope was acceptable. The customized 60 cm vessel-sealing device provided good hemostasis and a comfortable working length. Intraoperative complications included difficult viewing that prolonged operative time and inability to remove the second ovary in 1 mare. Postoperative recovery was excellent. Postmortem findings of 1 true positive microbial culture, elevated cell counts in abdominal fluid, and adhesion formation raise questions that must be addressed in future studies.


Using specialized instruments, transvaginal NOTES® ovariectomy is technically feasible in mares.