Breeders spend a substantial amount of time contemplating the logistics of breeding, such as choosing the stallion and where and who will be performing the reproductive work. But once a mare is in foal, a number of things can derail the pregnancy if veterinarians and horse owners don’t keep a close eye the mare’s progress. Sometimes, simply knowing the threats and being prepared to handle them can give a pregnant mare her best chances at carrying and delivering a healthy foal, noted Juan Samper, DVM, MSc, PhD, Dipl. ACT, of JCS Veterinary Reproductive Services Ltd., in British Columbia, Canada, during his presentation at the 2012 American Association of Equine Practitioners’ Convention, held Dec. 1-5 in Anaheim, Calif.

During his presentation Samper described five important factors for breeders and owners to consider that can negatively impact pregnancy, along with how to respond to them:

Early embryonic problems Cervical incompetence (which can lead to uterine infection) and inflammation of the uterine lining (called endometritis) are major risk factors for losing the pregnancy within the first 60 days of gestation. If the pregnancy does proceed, smoldering residual infections can cause problems closer to term.

"Often these mares are treated … with supplemental progesterone or progestins," said Samper, which are believed to help maintain pregnancy, but scientific evidence supporting this theory is lacking