Efficacy of laparoscopic ligation of the mesovarium of the mare in the standing position without removal of the ovary

The prospective controlled study with the ligation of the spermatic cord in abdominal cryptorchid horses by laparoscopic approach results in a functional castration. To examine the effect of ligation of the mesovarium on the functional viability of the ovary in five mares (one Dutch Warmblood and 4 Welsh ponies), from 3 to 16 years of age, with normal ovaries, the mesovarium, including the ovarian artery and vein, was ligated intra-abdominally using a laparoscopic technique in the standing position. The ovaries were left in place. Post-operative estrogen and progesterone levels were measured. Bilateral relaparoscopy was performed on day 14, day 28 and 5 months after the initial surgery in all 5 mares and the mares were subsequently euthanized. Autopsy was performed and the ovaries and uterus were examined macroscopically and histologically. Additionally, the same laparoscopic procedure was performed on 4 patients with informed consent of the owners. In result the mean oestrogen and progesterone level of 7 out of 9 mares were low after surgery. The procedure of a two-step ligation of the ovary, with out removing the ovary, was successful in 15 out of the 18 ovaries (83 %). In conclusion the castration of mares by ligation, without removal of the ovaries, by laparoscopic intervention is possible. The surgical technique for devitalisation of the ovaries is safe and represents a method of castrating in the standing patient in a minimal invasive way. However, the procedure resulted in effective castration only in 6 of the 9 mares (67 %). The failure was probably technique-based and further modification of the applied procedure is necessary to improve the success rate. The low number of mares limitates the significance of the study.