A mare’s pregnancy might not seem that complicated on the surface, but her relationship with the embryo and its adjacent parts–in total, the conceptus–is remarkably complex. In order to prevent early embryonic loss, the conceptus must interrupt her estrous cycle, signaling her uterus to create a receptive environment for attachment and growth.

Exactly how this "maternal recognition of pregnancy" occurs remains a mystery; however, researchers recently identified some of the genes involved–improving their understanding of early embryonic loss and how it might one day be prevented.

"The domestic horse is one of the few species in which the pregnancy recognition signal has not been established," explained Claudia Klein, Dr.med.vet., PhD, Dipl. ACT, ECAR, of the University of Kentucky’s Gluck Equine Research Center .

Researchers know that among mammals a horse’s pregnancy is unique : the conceptus is mobile in the uterus for nine to 18 days following ovulation; and a capsule surrounds the embryo like an egg shell. However, veterinarians are striving for a more comprehensive grasp of the earliest days of pregnancy