Domosedan

Uterine flushing was performed on day 6.5 after ovulation in both groups because embryos obtained from donor mares were vitrified. Animals were ultrasonographically monitored to evaluate the ovary (presence of corpus luteum) and uterus. For uterine flushing, mares were sedated with 20 µg/kg detomidine hydrochloride (Domosedan, Pfizer, Spain) and the vulva and perineum were then cleaned with povidone iodine. A Foley-type balloon-tipped catheter (Bioniche Animal Health, Pullman, USA) was lubricated with sterile, non-spermicidal gel, its tip was placed at the uterine lumen close to the cervix and the balloon was inflated with air. The uterus was flushed four times, using 1 litre of Ringer-lactate media at 37.5 °C each time, and the recovered fluid was filtered through an sterile in-line filter, pore size 73 µm (Miniflush, Minitube Iberica, Tarragona, Spain). Then the filter was opened in a laminar flow cabinet; in Group 2, the embryo was searched under a stereoscopic microscopy (Nikon SMZ645, Japan). The filter content was transferred to sterile 50-ml conical tubes, and bacteriological and cytological analyses were carried out.

Two-and three-dimensional ultrasonography was performed transrectally using the portable ultrasound device Voluson ® i (GE Healthcare, Zipf, Austria) equipped with a 3 to 9 MHz microconvex transducer (RNAs5-9-RS) which was protected by a rectal sleeve. Each mare was examined once transrectally by a single examiner at day 45 ± 1 of gestation. If necessary the mares were sedated once with 0.01-0.02mg/kg iv detomidinhydrochlorid (Domosedan®, Pfizer Animal Health, Elsene, Belgium). As soon as the fetus was localized by using 2D mode, three CRL measurements were acquired and the duration of the examinations was recorded. Afterwards, the examiner changed to 3D mode and started again to record the time of measurements. The sector angle and penetration depth were optimized for each fetus. The acquisition of 3D images was continued until three datasets were obtained. The 2D and 3D images were initially stored on the hard drive of the ultrasound device and transferred once weekly on an external hard drive.