Theriogenology. 2025 Oct 3;250:117700. doi: 10.1016/j.theriogenology.2025.117700. Online ahead of print.
ABSTRACT
Early embryonic loss (EEL), particularly between Days 14 and 42 of pregnancy, remains a key concern in equine reproduction. This study investigates the incidence of spontaneous luteolysis-used here as a marker of maternal recognition of pregnancy (MRP) failure-in both pregnant Thoroughbred (TB) broodmares and recipient mares carrying either in vivo-derived (IVD) or in vitro-produced (IVP) embryos. Retrospective reproductive data from 2078 pregnancies in TB and 532 pregnancies in recipients were analysed to determine the incidence and characteristics of clinical luteolysis during pregnancy. Overall, the incidence of EEL was 8.0, 8.7, and 13.5 % in broodmares, recipients with IVD and IVP embryos, respectively. Among pregnancies experiencing EEL, spontaneous luteolysis was observed in 18.7 %, 22.2 %, and 26.7 % of pregnancies in broodmares, IVD, and IVP embryo recipients, respectively. Among all pregnancies, the highest (P
PMID:41056618 | DOI:10.1016/j.theriogenology.2025.117700