Hormonal pattern in the blood of eight mares during the first weeks of pregnancy.

The research examines hormonal changes in horse blood during early pregnancy, with a particular focus on progesterone levels and its fluctuations. The study identified changes that may be indicative of early embryonic death.

Study Overview

• The study was undertaken on eight mares in their initial 5 to 6 weeks of pregnancy.
• The research specifically focused on the hormonal pattern in the blood of these mares. Progesterone was the primary hormone of interest.
• Two mares experienced early embryonic death on Days 28 and 40 respectively.

Findings & Observations

• Progesterone peaks were identified around Days 5, 10-12, and 17-18.
• Decreased progesterone levels during intervals were attributed to the action of estrogens.
• Between Days 18 and 34, both progesterone and pregnenolone levels were low in all the study subjects.
• A subsequent small increase in progesterone content was noted after Day 34.
• Occasionally, large amounts of “compound 5.4”, an isomer of pregnenolone, were found. This suggests the presence of follicles containing estradiol-17beta or perhaps an activated uterus.
• The study also proposed signs that might predict early embryonic death, such as low progesterone levels on Days 17-18, and no noticeable increase of progesterone or “compound 5.4” from Day 34 to Day 37. High pregnenolone levels on these days might indicate reduced conversion of pregnenolone to progesterone, which could potentially lead to embryonic death.

Significance of the Study

• The study provides key insights into hormonal changes during early stages of equine pregnancy.
• The findings provide detailed understanding of progesterone levels and fluctuations, which could serve as indicators of potential early embryonic death.
• This research can contribute to better veterinary care for pregnant mares and prevention of early embryonic death.