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Genetic Identification of Early Pregnancy Loss in MaresBy Kentucky Equine Research Staff · May 11, 2017

With the mare’s long gestation period and ability to only have one foal per year, pregnancy loss at any stage of gestation causes both economic and emotional hardship. For years, research has focused on both getting and keeping the mare in foal. New studies in human medicine suggest that measuring specific pieces of genetic material called microRNAs (miRNAs) could help veterinarians better diagnose pregnancy-related problems.

MicroRNAs are tiny units of RNA, genetic material that helps DNA create proteins and enzymes that make up tissues. Each tissue type produces unique miRNAs, much like fingerprints, that circulate in the bloodstream. Recent research shows that changes in the type or amount of circulating miRNAs can identify specific disease process. Examples include cancer, metabolic abnormalities, and pregnancy disorders such as placentitis and pre-term labor.

In horses, only limited studies have been conducted so far, and miRNA analyses confirm that circulating miRNAs are involved in maternal recognition of pregnancy.

According to one group of veterinary reproduction experts*, “circulating miRNAs have tremendous diagnostic potential for many similar pregnancy-related complications affecting horses and humans, including fetal growth restriction and placental infection. Earlier diagnosis allows for earlier intervention and a more favorable outcome.”

While research in the field of miRNA advances, equine nutritionists recommend other ways to optimize breeding efficiency in horses. Kathleen Crandell, Ph.D., a nutritionist with Kentucky Equine Research (KER), recommends the following:

  • Ensuring mares have an appropriate body condition score at each phase of gestation, including time of conception and early gestation;
  • Supplementing stallions with omega-3 fatty acids, such as marine-derived EO•3 to improve semen quality;
  • Supplementing broodmares with EO•3 for improving multiple aspects of the reproductive system and boosting colostrum quality;
  • Supplementing older broodmares with an antioxidant like a natural vitamin E, such as Nano•E, for improving cellular integrity;
  • Monitoring broodmares daily for vaginal discharge that could be an early sign of placentitis; and
  • Providing routine preventive health care, including appropriate vaccinations, deworming, and farriery.

*Loux, S.C., K.E. Scoggin, J.E. Bruemmer, et al. 2017. Evaluation of circulating miRNAs during late pregnancy in the mare. PLoS One. 12(4):e0175045.