关键词: 马属动物; 双胎妊娠; 诊断方法; 处置策略

Abstract: Twin pregnancy in equine species primarily originates from dizygotic twinning resulting from multiple ovulations,and its occurrence is influenced by factors such as breed,age,reproductive status and season.Certain breeds，for example,Thoroughbreds,Catalan donkeys and Mammoth donkeys,exhibit a higher incidence of double ovulation,and aged or barren mares also show elevated rates of twin pregnancies.Seasonal variations further modulate mare reproductive activity,thereby affecting the overall incidence of twin pregnancies.Twin gestation in equines can lead to complications including abortion,dystocia,and neonatal foal mortality,ultimately resulting in wasted reproductive resources and economic losses to the horse and donkey industries.Therefore,early diagnosis and timely management are critical for improving the survival rates of singleton pregnancies.The optimal diagnostic window for twin pregnancy is on gestational days 14 to 16,with transrectal ultrasonography being the preferred method due to its ability to accurately distinguish between embryonic vesicles and endometrial cysts.Depending on the stage of gestation,various management strategies may be applied.In early gestation (＜16 days),manual twin reduction using embryonic vesicle crushing yields the highest success rates and is effective for both unilaterally and bilaterally fixed twins.For gestational ages between 28 and 32 days,transvaginal ultrasound-guided aspiration is recommended to minimize adverse effects on the remaining embryo.Beyond 35 days,as fetal organ development advances,common techniques include oscillation,thoracic compression,cranio-cervical dislocation,or pharmacologically induced abortion.For late-stage twin pregnancies,the choice of management must be carefully balanced with the health condition of the mare,overall reproductive management goals,and the need for rigorous postoperative monitoring to reduce the risk of adverse outcomes.This review comprehensively examines the etiology,influencing factors,diagnostic methods and management strategies for equine twin pregnancy,aiming to enhance the understanding of veterinary practitioners,optimize reproductive management,mitigate pregnancy-associated risks,and ultimately improve embryo survival rates to promote the sustainable development of the horse and donkey industries.

Key words: equine; twin pregnancy; diagnostic methods; management strategies