Alterations of Circulating Biomarkers During Late Term Pregnancy Complications in the Horse Part II: Steroid Hormones and Alpha-Fetoprotein.
Authors: Fedorka Carleigh E, Ball Barry A, Wynn Michelle A A, McCormick Meghan E, Scoggin Kirsten E, Esteller-Vico Alejandro, Curry Thomas E, Kennedy Laura A, Squires Edward L, Troedsson Mats H T
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Preterm labour and abortion represent significant economic losses in equine breeding, yet clinical tools for early detection remain limited. Researchers prospectively collected weekly blood samples from 702 thoroughbred mares throughout pregnancy, then retrospectively analysed progesterone, oestradiol-17β and alpha-fetoprotein (AFP) concentrations from the five weeks surrounding parturition or abortion in 38 mares with confirmed placental pathology (ascending placentitis n=6, focal mucoid placentitis n=6, idiopathic abortion n=6, controls n=20). Both ascending and focal mucoid placentitis produced distinctive endocrine signatures—markedly elevated progesterone and AFP alongside decreased oestradiol-17β and a lower oestradiol-to-progesterone ratio—detectable across multiple weeks before pregnancy loss, whereas idiopathic abortions showed only progesterone decline and AFP elevation in the immediate week preceding loss. These findings suggest that infectious placental disease, including the previously under-characterised focal mucoid (Nocardioform) placentitis, produces measurable and sustained alterations in circulating biomarkers that could potentially support earlier clinical diagnosis and intervention, though field-based utility of these markers will require prospective validation in clinical populations with different risk profiles and disease prevalences.
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Practical Takeaways
- •Elevated serum progesterone and AFP alongside decreased estradiol-17β may help identify mares with ascending or focal mucoid placentitis; these biomarkers warrant field validation as diagnostic tools
- •The pattern of biomarker changes differs between infectious placentitis (multi-week alterations) and idiopathic abortion (acute, one-week changes), potentially enabling earlier detection of placental infection
- •Progesterone trends alone are insufficient to diagnose pregnancy complications—concurrent measurement of AFP and estradiol-17β ratios improves diagnostic accuracy and may reduce economic losses from preterm loss
Key Findings
- •Ascending and focal mucoid placentitis showed significant increases in progesterone and AFP with decreases in estradiol-17β compared to controls
- •The estradiol-17β to progesterone ratio was significantly decreased in infectious placentitis cases
- •Idiopathic abortions showed decreased progesterone and increased AFP only in the week preceding pregnancy loss, unlike infectious cases
- •This is the first study documenting altered steroid hormones and AFP during focal mucoid placentitis caused by Nocardioform organisms