The Equine Fetal Membranes. What is normal?

The University of Melbourne

  • Project code: PRO-017267

  • Project stage: Current

  • Project start date: Thursday, June 6, 2024

  • Project completion date: Monday, September 29, 2025

  • National Priority: HOR-Thoroughbred breeding


Approximately 5-10 % of pregnant mares will abort their foals yearly, causing significant economic losses, and potentially exposing other horses and on-site staff to increased health risks from transmissible infectious diseases. Examination of the lesions of fetal membranes from aborted foals is crucial to determine the cause of abortion, however, healthy foals may be delivered with fetal membranes exhibiting gross or histopathological lesions (Foote et al, 2012, Pazinato et al, 2016). The significance of these lesions is unknown in the context of normal healthy foaling’s, and these changes cannot be reliably interpreted without sound knowledge of the range of normal appearance of the equine fetal membranes. This research aims to determine whether the changes seen in apparently normal foaling’s are part of the normal spectrum of fetal membrane appearance, or if they represent pathology that is not sufficiently severe to cause equine abortion. The fetal membranes from mares delivering normal foals during the thoroughbred breeding season of 2023 will be examined for gross and histopathological lesions. Microbiome studies will be performed in selected cases to assess the metagenome of equine fetal membranes. The results will be correlated with foal health.


Thoroughbred Horses

Research Organisation

The University of Melbourne

Objective Summary

  1. Describe the visible and microscopic appearance of fetal placentas in normal foalings.
  2. Study the microorganism population in equine placentas.
  3. Training of a specialist pathologist in examining the equine placentas for diagnostic purposes.
  4. Link any placenta changes with the health of the foal.