Uterine and fetal dynamics during early pregnancy in mares.

The research article investigates the dynamics of the uterine and fetal activity during early pregnancy in mares. Using transrectal ultrasonography and transcervical videoendoscopy, the study focuses on changes in the diameter of the allantoic fluid compartment within uterine horns, and fetal activity and mobility.

Research Methodology

• The study examined mares between the 69th and 81st day of pregnancy using transrectal ultrasonography (n = 12) and transcervical videoendoscopy (n = 8).
• The placement of the videoendoscope’s insertion tube was within the allantoic sac to enable viewing of the fetus and the entrance to each uterine horn.
• Each uterine horn was divided into three equal-length segments using ultrasonography, with the designation of the horns based on the side of the umbilical cord attachment.

Finding of Allantoic Fluid Compartment Changes

• The diameter of the allantoic fluid compartment in the cornual segments showed significant increase across the cranial, middle and caudal segments. However, variations between cord and non-cord horns were not evident.
• Dynamic changes in the allantoic fluid compartment’s diameter in cornual segments were detected using both ultrasonography and videoendoscopy, with no significant discrepancies between the two methods reported.

Observations on Fetal Activity

• Continuous videoendoscopy observations, ranging from 17 to 60 minutes per mare, revealed extreme changes in the allantoic fluid compartment diameter, occurring approximately 2.6 times per hour per horn entrance. These changes typically lasted for an average duration of 3.4 minutes.
• Sometimes, the uterine wall was so closely constricted around the fetal-amniotic unit that no intervening allantoic fluid was detectable through ultrasonography. Conversely, at other times, the uterus in the same location was found to be widely dilated.

Significance of the Study

• The research provides valuable insights into the dynamics of the uterine and fetal activity during the early stages of pregnancy in mares. Through careful analysis of the changes in the allantoic fluid compartment and the corresponding fetal activity, the study contributes to the better understanding of equine pregnancy.