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Equine Health Resource

Early Embryonic Death, Generally

Synonyms: EED, Fetal Resorption

Fetal resorption is the early death of an embryo, the remains of which are absorbed by the mare. The first 40 days of a mare’s pregnancy is the time she is most at risk for this type of pregnancy loss. This is especially common in older mares that have uterine problems (resulting in inflammation) that make the uterus inhospitable to the developing embryo.

Other causes of EED include stress, malnutrition, extreme seasonal or climate changes, hormonal imbalance, uterine environment (including inflammation) and age.


  • What diagnostics can be run to best assess my mare's uterine health?
  • Could progesterone be involved in the pregnancy loss?
  • Can progesterone be tested for and supplemented to support pregnancy?

    Ultrasound examinations at 14 and 30-40 days helps to ensure normal fetal development. If problems are detected there may be an opportunity to remedy them. Blood progesterone determination may show that progesterone is low. This can be supplemented as necessary. Uterine diagnostics such as a biopsy proactively identifies mares that may require special treatment and management during pregnancy.

    Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

    Author: Doug Thal DVM Dipl. ABVP


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