Estrone sulfate concentrations as an indicator of fetal demise in horses.

This study explores the potential use of estrone sulfate concentrations as an early indicator of fetal demise in horses, suggesting that an increase in these concentrations could signify both expulsion or removal of the fetus as well as signal early pregnancy.

Objective of the Research

• The research was conducted to determine the source of estrogen, specifically estrone sulfate, during early pregnancy in mares. This was approached by examining serum and urinary estrone sulfate concentrations in pregnant mares, both when gestation was normal and after induced abortion or surgical removal of the fetus.
• It also sought to evaluate the potential of estrone sulfate concentrations as a potential diagnostic tool to assess fetal viability after Day 44 of gestation (GD 44) in mares.

Methodology

• The study involved seven pregnant mares, with four undergoing prostaglandin-induced abortion and three having their fetuses surgically removed.
• The concentrations of estrone sulfate in both serum and urine were studied before and after these interventions.
• In addition, the research examined serum samples (which had been frozen for two years) from three other mares that had been ovariectomized (ovaries removed) between GD 51 and 58. This helped to understand the variation in estrone sulfate concentrations after ovariectomy.

Findings

• The study found that estrone sulfate concentrations decreased in serum and urine following the expulsion or removal of a fetus. The urinary patterns were found to be more definitive than those manifesting in the serum.
• It was also observed that a temporary decrease in serum estrone sulfate concentrations occurred after the mares underwent ovariectomy.
• These observations led to the conclusion that the major source of estrone sulfate during early pregnancy is products of conception, but there appears to be some ovarian contribution as well.

Significance and Conclusion

• This study suggests that measuring serum or urinary estrone sulfate could provide a simple and accurate method to test for fetal viability after GD 44 in mares.
• This method could be employed in equine health checks, particularly surrounding pregnancy and abortions, and could provide veterinary medical professionals with vital information for managing and monitoring mare pregnancies.