Relaxin and placental dysfunction in the horse

Abstract

The equine industry would benefit from a hormonal indicator that reflects placental and fetal well-being in the horse. Pregnancy loss during the third trimester and death of foals weakened by abnormal periparturient events constitute a large percentage of fetal and neonatal mortality [1]. Due to the expense of breeding contracts and the long gestation of the mare, late-term fetal death represents a major financial loss and time investment for the breeder. Early identification of placental insufficiency would make it possible, in some cases, to sustain the pregnancy through medical intervention. Furthermore, aggressive prepartum therapy affords foals a better chance of survival. For example, when placental function is compromised in mares suffering from fescue toxicosis, timely drug therapy rescues the placenta and improves pregnancy outcome [2,3,4,5]. Likewise, if diagnosed early, placentitis can be treated with systemic antibiotics, progestins (progesterone, 17α-hydroxyprogesterone, 5α-pregnanes), non-steroidal anti-inflammatory drugs or steroids (cortisol, to hasten fetal organ maturation).