Equine Reproductive Health and Pregnancy Outcomes

Equine reproductive health encompasses the complex interplay of mare physiology, management practices and environmental influences that determine successful conception, gestation and foaling. Mares exhibit seasonal polyoestrous cycles governed by photoperiod, with follicular dynamics and corpus luteum function critical for establishing and maintaining pregnancy. Early embryonic loss, affecting up to 10 per cent of pregnancies, often reflects intrinsic embryonic defects, uterine environment abnormalities or suboptimal hormonal support. Mid- and late-term losses arise from infectious agents, placental pathologies, umbilical cord complications or genetic anomalies, each carrying substantial economic and welfare implications for breeding operations worldwide. Advances in ultrasonography, endocrine monitoring and assisted reproductive technologies, including embryo transfer and selective reduction of multiple pregnancies, have improved diagnostic precision and intervention timing. Rigorous hygiene, nutritional optimisation and targeted vaccination strategies mitigate infectious risks, while ongoing research seeks to elucidate genetic contributions to foetal viability and refine management protocols to reduce pregnancy failure and enhance global equine breeding outcomes.

Research from Nature Portfolio

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Equine Reproductive Health and Pregnancy Outcomes publication trend

The graph below shows the total number of articles in equine reproductive health and pregnancy outcomes across all publications each year (not limited to Nature Index journals).

Technical terms

Umbilical cord torsion: Twisting of the umbilical cord that impedes foetal blood flow and can result in abortion or stillbirth.

Intrauterine growth retardation (IUGR): Failure of the foetus to achieve its genetically predetermined growth rate, often detected by reduced crown–rump length.

Dizygotic twins: Twins derived from two separate ova fertilised by different sperm, each with distinct genetic profiles, frequently subject to selective reduction.

Monozygotic twins: Twins originating from a single fertilised ovum that splits, sharing identical genetic material and posing greater management challenges.

Placentitis: Inflammation of the placenta, which compromises nutrient and oxygen exchange and increases the risk of pregnancy loss.

References

1. A Scoping Review of the Global Distribution of Causes and Syndromes Associated with Mid- to Late-Term Pregnancy Loss in Horses between 1960 and 2020. Veterinary Sciences (2022).
2. Potential risk factors for fetal loss due to umbilical cord torsion in the mare. Theriogenology (2023).
3. Ultrasound‐guided fetal thorax compression to reduce post‐fixation twins in the mare. Equine Veterinary Journal (2024).