Placental abnormalities in equine pregnancies generated by SCNT from one donor horse.

The research examines changes in the placentas of horse pregnancies achieved through Somatic Cell Nuclear Transfer (SCNT) from a single horse. It reveals that these pregnancies are often distinguished by placental pathologies, some of which can be detected using ultrasonography, and may lead to pregnancy loss.

Study Design and Methodology

• The research team examined the ultrasonographic, gross, and histopathological qualities of placentas from three successful and five unsuccessful horse pregnancies achieved by SCNT. These pregnancies used cells sourced from a singular donor horse.
• Starting from around the 6-month gestation period, the team monitored the pregnancies using both transrectal (TR) and transabdominal (TA) ultrasonography. This allowed the team to examine the fetuses, the fetal fluids, and the placentas.
• If abnormalities were found, they were noted and analyzed. For instance, one mare experienced abortion without any detectable abnormalities, while four had enlarged umbilical vessels visible before abortion.

Findings

• Of the mares that experienced abortion, TR and TA ultrasonography detected placental edema and intravascular thrombi in the umbilical cords in two cases. Acute placental separation was noted in one mare, leading to abortion shortly after detection.
• In the three live birth cases, TA ultrasonography showed enlarged umbilical vessels and engorged allantoic vessels. Two of these cases also had detectable placental thickening, which was interpreted as placentitis. Active medical treatment resulted in the subsidence of these symptoms.
• From the eight pregnancies, seven placentas were submitted for further examination post-delivery. All displayed some degree of edema, enlarged umbilical vessels, and abnormally engorged allantoic vessels. Placentitis, cystic pouches in the fetal part of the cord, large allantoic vesicles, and hemorrhages and thrombi in the umbilical vessels were only found in mares that had aborted.

Conclusion and Implications

• SCNT in equine pregnancies could be associated with a variety of placental pathologies. Using ultrasonography, the research team was able to detect these abnormalities. However, gauging their severity can be challenging.
• The research findings noted an occurrence of placentitis in these pregnancies, resulting in some cases in pregnancy loss.
• The research team suggests that further investigation is required as placentitis hasn’t been reported previously in SCNT pregnancies in horses. Improved understanding of these pathologies could lead to better prevention and treatment strategies, potentially reducing pregnancy loss rates in equine SCNT pregnancies.