Twin reduction in the mare: current options

Efficacy of transvaginal ultrasound-guided twin reduction in the mare by embryonic or fetal stabbing compared with yolk sac or allantoic fluid aspiration

“…In the case of transabdominal ultrasound-guided twin reductions, it is accepted that the placenta of the surviving twin is never able to regain the endometrial attachment area 'lost' to its cotwin, leading to an increased risk of placental insufficiency later in gestation that can result in abortion or the birth of a emaciated foal [12,13] despite mummification of its twin; placental insufficiency following TUGR has not been reported, but could conceivably be an issue if The likelihood of success in the current study was not significantly influenced by the technique used for TUGR, which is in agreement with the observations of Govaere et al [5] for mares with unilateral twins. One of the biggest risks of performing allantoic/yolk-sac fluid aspiration in unilateral twins is damage to the developing membranes or to the chorioallantoic-endometrial attachment of the co-twin as a result of puncture, accidental aspiration, leakage of fluid and/or collapse of the manipulated vesicle [1]. Moreover, fluid aspiration can be time-consuming because the needle can become obstructed by membranes forcing the operator either to stop or reposition the needle in order aspirate the desired amount of fluid.…”

“…Indeed, post-TUGR the mares' uteri were deliberately not examined because the pressure exerted during examination might increase the risk of fluid leakage. Fluid aspiration should theoretically be more appropriate for bilateral twin pregnancies, where the operator has more flexibility with regard to how the conceptus is penetrated since the risk of directly damaging the other twin [1] is low, and removal of as much fluid as possible will remove the risk of leaked fluid bathing and potentially compromising the remaining pregnancy.…”

“…Transvaginal ultrasound-guided pregnancy reduction (TUGR) is a procedure described for the management of post-fixation twins [1,2]. The success of TUGR has been reported to be largely dependent on operator experience [1,2], and the gestational stage (before or after day 35 of gestation [3,4]) and relative position (uni-or bilateral [3]) of the two vesicles.…”

“…The success of TUGR has been reported to be largely dependent on operator experience [1,2], and the gestational stage (before or after day 35 of gestation [3,4]) and relative position (uni-or bilateral [3]) of the two vesicles. TUGR was first reported in mares by Bracher et al [3] who reported a viable singleton 10 days after the procedure in six of 13 (6/13; 46%) treated mares; in their study, the procedure had a higher success rate in the case of bilaterally-located twins (3/4; 75% versus 3/9; 33%) and, was more successful for unilateral twins, when performed before day 35 of gestation (2/5; 40% versus 1/4; 25%).…”

Factors Concerning Early Embryonic Death in Thoroughbred Mares in South Korea

“…As a means of preventing these side effects, multiple pregnancies can be manually reduced to a single embryo by performing a selective reduction procedure this has a 90% success rate when performed before the placenta is formed. However, rough handling can result in complete embryonic death [13,15,16,21,24,28]. In a study of early embryonic death in mares bred in 1985 that was based on the number of embryonic vesicles, Woods et al [37] reported that the early embryonic death rate for multiple pregnancies (24.4%, 10/41) was greater than for single pregnancies (12.5%, 70/559).…”