Morphological Characteristics of the Placenta and Umbilical Cord of Arabian Mares Foaling in the United Arab Emirates.

This study investigates the physical features of the placenta and umbilical cord in Arabian mares that have given birth in the United Arab Emirates, focusing particularly on any differences in these features when compared to other breeds, and the potential influences on these characteristics.

Research Methodology

• The researchers studied 127 placentas from Arabian mares in the United Arab Emirates.
• The dimensions of the placenta were measured and compared to known records for Thoroughbred mares.
• Differences in the size of the allantochorion, one of the membranes making up the placenta, were examined between mares that were giving birth for the first time (primigravid) and those who had given birth previously (multiparous).
• The positions of the pregnant horn (the part of the uterus where the embryo implants and grows) and the umbilical cord attachment were noted.
• The total length of the umbilical cord was measured, along with the lengths of its two component parts: the allantoic portion and the amniotic portion.
• Details were also recorded regarding any presence of an enlarged yolk sac remnant (YSR) in the placentas.

Results

• The dimensions of the placentas observed were generally smaller than those recorded for Thoroughbreds.
• Significant differences in the size of the allantochorion between primigravid and multiparous mares were seen only in the linear dimensions of the body portion.
• In most cases, the pregnant horn was situated on the right side of the uterus and the umbilical cord was attached primarily at the base of the two placental horns.
• During measurement of the umbilical cords, it was found that the amniotic portion was typically, though not always, longer than the allantoic portion.
• Longer cords were associated with a greater proportion of allantoic length, and cords with YSRs exhibited significantly longer allantoic portions than those without.
• They also found that, contrary to expectation, total umbilical cord length had no correlation with various factors such as the weight or area of the allantochorion or amnion, the gestation period, or the foal’s birth weight, sex or month of birth.
• The researchers discovered that the purpose for which the mare was bred did influence umbilical cord length, with show mares having significantly longer cords than racing mares.

The detailed examination of these placentas and umbilical cords provides valuable insight into the unique physiological features of foaling in Arabian mares and enhances our understanding of equine reproductive biology.