Which Biomarkers Best Predict Late-Term Pregnancy Loss?

Scientists tested whether estradiol-17B, progesterone, alpha fetoprotein, and/or serum amyloid A could predict abortion.

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Late-term pregnancy loss in mares continues to be a significant problem in reproduction practice. In recent years, researchers have identified several biomarkers that can indicate when trouble’s brewing, but hadn’t yet done a large-scale field study to evaluate them.

So a team from the University of Kentucky examined changes that occurred in four established biomarkers in mares with both normal and abnormal pregnancy outcomes. Barry Ball, DVM, Dipl. ACT, presented their results at the 2016 American Association of Equine Practitioners’ Convention, held Dec. 3-6 in Orlando, Florida.

The biomarkers of interest in this study were:

  • The estrogen estradiol-17B The fetus and placenta produce estradiol during pregnancy. Previous study results have shown that estradiol levels decrease when experimental placentitis is induced at nine months of gestation.
  • Progesterone The placenta plays a large role in progesterone metabolism. Progesterone falls to low or nondetectable concentrations during gestation. When researchers induced experimental placentitis at nine months, however, these levels increased in the days before abortion.
  • Alpha fetoprotein (AFP) This protein is present in the fetal fluids and can cross the placenta into the maternal circulation. Concentrations increase in mares with induced placentitis.
  • Serum amyloid A (SAA) This biomarker increases in response to any inflammation in the body and has been shown to increase in pregnant mares a few days post-placentitis induction.

In their study, Ball and his team recruited 700 mares from 15 Thoroughbred farms in Central Kentucky. Starting in December, they collected blood samples weekly until the mares either foaled or aborted. From this group, 15 mares aborted (8) or had lesions present on their placentas after foaling (7). For the purpose of the study, the team matched each of these mares with two matched control mares

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Written by:

Alexandra Beckstett, a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as assistant editor of its book division, Eclipse Press, before joining The Horse. She was the managing editor of The Horse for nearly 14 years and is now editorial director of EquiManagement and My New Horse, sister publications of The Horse.

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