Post-partum concentrations of serum progesterone, oestradiol and prolactin in Arabian mares demonstrating normal maternal behaviour and Arabian mares demonstrating foal rejection behaviour.

This research study aimed to understand whether hormonal changes could be causing abnormal maternal behavior, specifically foal rejection, in Arabian mares post-childbirth. The researchers found no significant differences in progesterone, oestradiol, and prolactin levels between mares that rejected their foals and those that did not. However, they found significant decreases in progesterone and prolactin levels between the first and third days post-childbirth in both groups while oestradiol levels remained unchanged.

Study Design and Participants

• The researchers conducted a prospective study where they monitored two groups of Arabian mares.
• The first group consisted of mares that showed normal motherly behavior after giving birth (8 mares).
• The second group consisted of mares that displayed foal-rejecting behavior post-childbirth (15 mares).
• Most of the mares were observed and samples were taken twice: on the first and third days post-childbirth.

Measurement and Results Overview

• Blood serum samples taken from the mares were used to measure concentrations of three hormones: progesterone, oestradiol, and prolactin.
• The researchers found no significant differences in the levels of these hormones between the normal mares and those that rejected their foals.
• Despite the lack of difference between the groups, within the foal-rejecting mares group, there was a significant decrease in concentrations of progesterone and prolactin from the first to the third day after giving birth.
• In contrast, in the group of mares with normal maternal behaviors, only the progesterone concentration significantly decreased from days 1 to 3 post-childbirth.
• The oestradiol concentration did not change significantly in both groups.

Analyzing Hormone Ratios

• The researchers also analyzed the oestradiol to progesterone ratio and found it was significantly higher in the non-rejecting mares on the first day after childbirth.
• This ratio also increased significantly from the first to the third day in foal-rejecting mares.

Implications of the Findings

• Although no significant differences were found in hormone levels between the two groups, the findings suggest potential hormonal changes within the foal-rejecting mares that may contribute to this behavioral issue.
• The decrease in progesterone and prolactin within the foal-rejecting mares, as well as the increased oestradiol to progesterone ratio, could be indicative of hormonal dysregulation that affects post-partum behavior in these mares.
• However, further research is needed to establish a causal relationship between these hormonal changes and foal-rejecting behavior.