What to do and when: management of equine twin pregnancies

Abstract

The use of ultrasound to diagnose pregnancy early in the mare, has aided veterinarians' ability to identify twins before fixation, allowing manual reduction to be performed with the highest success rate of delivering a single live foal. Unfortunately, when pregnancy diagnosis is delayed and dizygotic or monozygotic twins are identified post-fixation, the success rates of a normal-sized healthy foal decreases. Depending on the stage of gestation different procedures have varying degrees of invasiveness, and live foaling rates. These options may include manual and natural reduction, transvaginal ultrasound-guided reduction, oscillation, thoracic compression, cranio-cervical dislocation, transcutaneous ultrasound-guided injection and induction of abortion. Manual reduction prior to fixation has the highest success for the birth of a normal-sized single foal. Oscillation and thoracic compression are less invasive than procedures later in gestation and appear to have the best success rate before 65 days with cranio-cervical dislocation a better option later in gestation. Early identification of twins allows for determination of the optimum procedure for reduction, increasing the chances of the birth of a normal-sized individual foal.