Videoendoscopic evaluation of the mare’s uterus: III. Findings in the pregnant mare.

This research paper covers a five-year study on the use of videoendoscopic hysteroscopy in 65 Pony and 20 Thoroughbred pregnant mares. The study aimed to observe fetal and placental development, eliminate twin conception, recover embryonic fetal tissues for experimental purposes, and induce placenta separation.

Overview of the Study

• The research paper is an investigative study carried out over a span of five years, focusing on 65 Pony and 20 Thoroughbred pregnant mares.
• These mares were subjected to videoendoscopic hysteroscopy, a procedure using a tiny camera inserted into the uterus, during various stages of their gestation period ranging from 10 to 266 days.
• The purpose of these examinations varied, with objectives including observing fetal and placental development, eliminating select twin pregnancies, retrieving embryonic fetal and placental tissues non-invasively for research, and creating a model of placentitis by inducing local placenta separation.

Main Findings of the Study

• The study allowed a view of the embryo and all extraneous embryonic membranes of the conceptus between 10 and 87 days of gestation without puncturing the allantochorion (the outermost embryonic membrane).
• Physiological processes such as uterine contractions responsible for embryo movement and the beginning of active fetal movements, observed as early as Day 34, were studied.
• The research also witnessed the invasion of chorionic girdle cells into the endometrium happening between the 34th and 38th days.
• However, visibility of the fetus was reduced or blocked due to increased thickness of the allantochorion past the 90th day.

Concerning the Recovery of Conceptus and Twin Elimination

• Recovery of the conceptus using the transendoscopic method was successful for all mares under 30 days of gestation, while attempts after Day 30 achieved mixed results.
• The study experiences failure in all attempts to eliminate one of the twins in a unilateral pregnancy. This led to the researchers abandoning the technique as it proved to be unsuitable in a clinical setting.
• However, 41% single pregnancies remained viable after one or more hysteroscopic examinations.