Evaluation of systemic relaxin blood profiles in horses as a means of assessing placental function in high-risk pregnancies and responsiveness to therapeutic strategies.

This research study aims to assess placental function in high-risk pregnancies in horses. The researchers propose circulating relaxin, a hormone produced by the placenta, as a potential biomarker that could indicate placental health and predict pregnancy outcomes, and they use this marker to assess the response to different therapeutic interventions.

Objective of the Research

• The primary objective of this research was to evaluate placental function in high-risk horse pregnancies. In doing so, the researchers aimed to identify potential issues early enough to intervene therapeutically and prevent late-term abortion or perinatal death of the foals.
• A secondary aim was to explore the function of relaxin, a hormone produced solely by the placenta, as a biomarker for placental function and fetal health. This could potentially act as a predictor of pregnancy outcomes.

Methodology

• The researchers monitored plasma levels of relaxin in mares (light breeds) with normal and problem pregnancies. This included clinical cases presented to the veterinary hospital and mares experimentally infected with Streptococcus equi zooepidemicus to induce uterine infection (placentitis).
• Upon the establishment of placentitis, the mares were assigned to different therapeutic strategies, and their response was monitored.
• Blood samples were collected during the third trimester of the mares’ pregnancies, and the relaxin content was determined using a homologous equine relaxin radioimmunoassay.

Key Findings

• The study found a positive relationship between low circulating relaxin levels and poor pregnancy outcomes in mares with compromised placental function, suggesting the potential utility of relaxin as a diagnostic trial for high-risk pregnancies associated with placental dysfunction.
• However, the varying results from mares receiving drug treatments for experimentally induced placentitis make it challenging to determine the reliability of relaxin as a way to evaluate the efficacy of therapeutic interventions.

Implications

• The findings of this study can potentially aid in the early identification of pregnancy risks in horses, enabling early therapeutic intervention to potentially sustain the pregnancy and reduce the risks of late-term abortion and perinatal foal death.
• However, more research is needed to reliably use relaxin to evaluate the efficacy of therapeutic strategies aimed at preserving high-risk pregnancies.