Incidence and nature of disorientation of the embryo proper and spontaneous correction in mares

Abstract

Summary Orientation of the embryo proper at the periphery of the equine embryonic vesicle is normally antimesometrial or on the ventral aspect of the embryonic vesicle (6 o'clock relative to 12 o'clock at the center of the mesometrial attachment). An early ultrasonographically detectable vascular endometrial indicator of the future position of the embryo proper has been reported previously and was first detected in a mean 2.5 days before detection of the embryo proper. In the current study, four occurrences of disorientation of the embryo proper were found in a group of 30 mares (incidence, 13%). When first detected, the early indicator of the clock-face position of the embryonic pole for the disorientation and normal orientation group, respectively, was 1.3 ± 0.3 and 0.4 ± 0.1 hours from the 6 o'clock position ( P