Fertility of mares after unilateral laparoscopic tubal ligation

Objective-To develop a technique for laparoscopic tubal (oviductal) ligatio n and to evaluate pregnancy rates for mares that ovulated ipsilateral or co ntralateral to the ligated oviduct. Study Design-Randomized prospective clinical trial comparing pregnancy rate s after unilateral laparoscopic tubal ligation. Animals-Twelve mares of light horse breeds. Methods-One oviduct in each of 6 mares was surgically ligated with a laparo scopic technique; 6 other mares served as nonligated controls. Mares with u nilateral tubal ligations (UTL) were inseminated with 500 million progressi vely motile sperm during 1 cycle when the dominant follicle was ipsilateral to the ligation site and 1 cycle when the dominant follicle was contralate ral to the ligation site. Control mares were bred during 2 cycles regardles s of the side of the dominant follicle. Pregnancy examinations were perform ed on days 12, 14, and 16 after ovulation by transrectal ultrasonography. Results-None of the mares became pregnant when ovulations occurred from the ovary adjacent to the ligated oviduct. All 6 mares became pregnant on the first cycle when an ovulation occurred from the opposite ovary. Control mar es became pregnant on 10 of 12 cycles (83.3 %). Conclusions-UTL was completely effective in preventing pregnancy when ovula tion occurred ipsilateral to the ligation site. The surgical procedure did not interfere with the establishment of pregnancy when ovulation occurred f rom the contralateral ovary. Clinical Relevance-UTL may be a clinically useful procedure for preparing a recipient mare for gamete intrafallopian transfer. The recipient mare coul d be allowed to ovulate and UTL would prevent fertilization of her oocyte b ut would not interfere with normal corpus luteum formation. The donor oocyt e could be placed into the oviduct contralateral to the UTL site. (C) Copyr ight 2000 by The American College of Veterinary Surgeons.