Histological and biomechanical properties of systemic arteries in young and old Warmblood horses.
Authors: Vera Lisse, Muylle Sofie, Van Steenkiste Glenn, Segers Patrick, Decloedt Annelies, Chiers Koen, van Loon Gunther
Journal: PloS one
Summary
# Editorial Summary: Arterial ageing and rupture risk in horses Arterial rupture remains a significant cause of sudden death in equine practice, with older horses bearing disproportionate risk, yet the structural and functional changes underpinning this age-related vulnerability have been poorly characterised. Researchers compared arterial tissue from six young (6-year-old) and fourteen aged (≥15-year-old) Warmbloods, performing histological analysis and biomechanical testing on samples from the aorta, carotid, iliac and femoral arteries using an inflation-extension apparatus with ultrasound imaging. Older horses demonstrated markedly thickened intima-media layers and significantly elevated smooth muscle actin content, whilst rupture during high-pressure mechanical testing (250–300 mmHg) occurred almost exclusively in aged animals (7 of 8 rupture events). Pressure-area, pressure-compliance and pressure-distensibility curves revealed significant age-related differences across multiple arterial beds, particularly in the distal aorta, common carotid and external iliac arteries. These findings suggest that progressive arterial stiffening and structural remodelling in ageing horses compromises vessel elasticity and load-bearing capacity—a mechanism that may inform preventative strategies around exercise intensity in older animals and warrants consideration of vascular integrity when assessing fitness and risk in geriatric equine patients.
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Practical Takeaways
- •Older horses (≥15 years) have substantially stiffer, more fragile arterial walls that are at greater risk of rupture during exercise or exertion — consider this when evaluating sudden death cases and assessing exercise tolerance in aged animals
- •Arterial rupture remains an unpredictable but real risk in geriatric horses; awareness of this condition may inform decision-making around intensive exercise or veterinary procedures requiring sustained cardiovascular stress
- •Age-related arterial changes are structural and progressive; routine monitoring of vascular health in older horses may help identify high-risk individuals, though no preventive interventions are yet established
Key Findings
- •Older horses (≥15 years) showed significantly greater intima media thickness and higher smooth muscle actin area compared to young horses (6 years)
- •Arterial rupture occurred in 8/78 samples at pressures between 250-300 mmHg, with 7/8 ruptures occurring in older horses
- •Significant age-related differences in pressure-area curves of distal aorta, common carotid, and external iliac arteries, with reduced compliance and distensibility in older horses
- •Age-related arterial wall stiffening and structural remodeling may explain the higher incidence of arterial rupture in aged horses