North American Veterinary Licensing Examination (NAVLE) Practice Test

After the allantoic fluid rushes out from a pregnant mare, what can be expected as the next event in normal parturition?

1. The placenta is expelled from the vulva

2. The hind legs of the foal emerge from the vulva

3. The red, velvety chorioallantoic membrane emerges from the vulva

4. The thin, white, glistening amniotic membrane emerges from the vulva

The correct answer is: The thin, white, glistening amniotic membrane emerges from the vulva

During normal equine parturition, the expulsion of the allantoic fluid indicates that the mare is entering the second stage of labor. Following this, the next observable event is the emergence of the thin, white, glistening amniotic membrane from the vulva. This membrane encases the foal and provides a protective environment during the birth process. The presence of the amniotic membrane suggests that the foal is positioned correctly for delivery, with its limbs and head leading the way. The emergence of this thin membrane is typically indicative of impending foal delivery, which is crucial in the process of parturition. In contrast, while the expulsion of the chorioallantoic membrane can occur shortly before or after the foal is born, it typically comes later in the sequence of events. The expulsion of the placenta follows the birth of the foal, marking a significant stage in the postpartum process rather than directly after the allantoic fluid release. Therefore, understanding the typical sequence of events is vital to anticipating normal labor progress in mares.