Physiological development of the equine fetus during late gestation.
Authors: Fowden A L, Giussani D A, Forhead A J
Journal: Equine veterinary journal
Summary
# Editorial Summary: Physiological Development of the Equine Fetus During Late Gestation Fowden, Giussani and Forhead's 2020 review synthesises current understanding of how metabolic, cardiovascular and endocrine systems develop in the equine fetus during the second half of gestation, and crucially, how maternal stressors—including nutritional deficiency, placental insufficiency and systemic disease—programme lasting changes in the foal's adult phenotype. By examining the equine placenta's role as a mediator of fetal adaptation to environmental cues, the authors establish that developmental perturbations during late pregnancy create measurable shifts in postnatal metabolism, cardiovascular function and growth trajectory that persist well into maturity. The evidence presented indicates that the immediate perinatal period represents a critical window of susceptibility; foals born with abnormal bodyweight, prematurely, or showing dysmature characteristics demonstrate measurable phenotypic differences in later life, with implications for both health and athletic potential. For equine practitioners, this review underscores why apparently "normal" neonatal presentations may mask underlying metabolic or cardiovascular vulnerabilities acquired in utero, and highlights the importance of monitoring in-utero development status and maternal wellbeing as preventative strategies. Understanding these developmental programming mechanisms—particularly in high-risk pregnancies involving assisted reproduction, maternal malnutrition or placental compromise—offers practical direction for managing long-term soundness, metabolic resilience and performance capacity.
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Practical Takeaways
- •Monitor pregnant mares for nutritional adequacy and stress levels during late gestation, as these factors significantly affect fetal development and subsequent foal health and performance potential
- •Be alert to foals born prematurely, with abnormal body weight, or with dysmature characteristics, as they have programming alterations affecting metabolism, cardiovascular function, and growth trajectory throughout life
- •Optimize neonatal management and early life environmental conditions as critical intervention points to minimize long-term metabolic, cardiovascular, and musculoskeletal disease risk in performance horses
Key Findings
- •Fetal physiological development during late gestation in horses is influenced by maternal nutrition, disease, placental insufficiency, and social stresses with long-term phenotypic consequences
- •The equine placenta and fetal endocrine glands mediate adaptive responses to hypoglycemia and hypotension during late gestation
- •Early life environmental factors and the immediate neonatal period represent critical windows for developmental programming of metabolic, cardiovascular, and endocrine phenotype
- •Abnormal birth weight, prematurity, dysmature characteristics, and assisted reproductive technologies indicate altered early life environment with potential health and athletic performance implications