The hypothalamic-pituitary-adrenal axis and perinatal treatment of premature foals
CortisolGlucocorticoidsACTHHPA-axisFetal developmentEquine gestationInduction of parturitionPremature foal and glucocorticoid treatment
The danger and vulnerability associated with a preterm birth seem to be closely correlated with a dysfunction of the fetal hypothalamic-pituitary-adrenal (HPA) axis, whose maturation in the foal is without a doubt as delicate as it is important. Not only is this endocrine cascade
vital for the foal in order to cope with neonatal stress, it also appears to be fundamental for the final fetal intrauterine maturation, as well as for the onset of foaling.
Equine gestation exhibits some rather unique features, indicating a somewhat different significance of the endocrine changes associated with HPA maturation, compared to many other species. This hormonal cascade is rapid and confined to a narrow time during late gestation in the horse, and the risk of the foal completely missing it therefore becomes prominent.
Induced parturition in the mare may be operated through uterotonic agents, which occasionally bring about premature foals. Desirable seems the ability to initiate equine labour
while simultaneously enhancing fetal HPA maturation, as in humans and ruminants through perinatal glucocorticoid administration. However, similar treatment in the horse has resulted in various, sometimes fatal, outcomes.
In the light of the distinctive features of equine gestation, difficulties are encountered following such administration of glucocorticoids and ACTH. Favourable results have however also been displayed in the horse, motivating attempts to overcome the associated
obstacles. To ensure a successful therapy, increased knowledge about the endocrinology of equine gestation will be necessary.