Oestrone and equilin in the plasma of the pregnant mare.

This research study investigates the levels of oestrone and equilin — two hormones — in the blood of pregnant horses and notes fluctuations at different stages of pregnancy.

Methodology

• The researchers explain a method they’ve developed to extract two hormones, oestrone and equilin, from the plasma (the liquid part of blood) of pregnant mares (female horses).
• They applied this method to gather data from 82 blood samples taken from 14 Welsh Mountain Ponies during various stages of their pregnancies.

Results and Observations

• It was found that there was no trace of either oestrone or equilin in the plasma before the 120th day of pregnancy (oestrone was checked in 15 samples and equilin in 3).
• From the 120th to the 240th day of pregnancy, levels of oestrone were found to exceed 100 nanograms per millilitre (ng/ml), after which point they started to decline until birth.
• The surge of oestrone in the middle of pregnancy coincided with a gradual increase in equilin concentration, which plateaued after the 180th day at around 100 ng/ml. Significant decreases in equilin levels were only identified in the final month of pregnancy.

Key Findings

• Based on these evidences, it was suggested that both oestrone and equilin are present in the peripheral plasma, the plasma on the edge of the bloodstream, mainly in the form of sulphates.
• This conclusion suggests that it is not only the presence of these hormones but also the manner in which they are carried in the bloodstream, in this case as sulphates, may affect their function during pregnancy.