Age-Related Differences in Short-Term Transportation Stress Responses of Horses.
Authors: Jacquay Erica T, Harris Patricia A, Adams Amanda A
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Age-Related Differences in Short-Term Transportation Stress Responses of Horses Whilst transportation stress in horses is well documented, little evidence exists on how ageing influences physiological responses to short journeys. Researchers compared stress markers in five aged mares (22 ± 1 years) and six young mares (2 ± 1 years) during a 1 hour 20 minute transport, collecting blood and saliva samples at multiple timepoints from baseline through eight days post-transport to measure cortisol, ACTH, insulin, heart rate, temperature and inflammatory cytokine expression. Both age groups showed comparable elevations in serum and salivary cortisol and heart rate during transport, yet aged horses demonstrated higher baseline and post-transport ACTH levels and a substantially greater insulin response than younger animals, whilst young horses exhibited higher rectal and under-tail temperatures. The findings suggest that whilst the hypothalamic-pituitary-adrenal axis responds similarly across ages, aged horses mount a distinct metabolic stress response characterised by heightened insulin dysregulation—a clinically relevant observation given that insulin resistance and metabolic dysfunction are already prevalent concerns in older equine populations. For practitioners, this indicates that ageing horses may require particular attention to post-transport metabolic management and glucose regulation, potentially through tailored feeding strategies and monitoring protocols distinct from those applied to younger animals.
Read the full abstract on PubMed
Practical Takeaways
- •Age does not affect cortisol-mediated stress responses to short transportation, so standard stress management protocols apply equally to young and aged horses during transit
- •Aged horses show greater metabolic stress (elevated ACTH and insulin) during transportation, suggesting they may require additional monitoring for metabolic complications and post-transport recovery time
- •Young horses maintain higher body temperatures during transportation stress, which may indicate different thermoregulatory capacity and should be considered when managing ventilation and hydration during transit
Key Findings
- •Serum cortisol, salivary cortisol, and heart rate increased significantly in response to 1 hour 20 minute transportation with no differences between aged (22±1 years) and young (2±1 years) mares (P<0.0001, P<0.0001, P=0.0002 respectively)
- •Rectal and under-tail temperatures were significantly higher in young horses compared to aged horses post-transportation (P=0.03 and P=0.02)
- •Aged horses showed significantly higher ACTH levels both at baseline and post-transportation (P=0.007 and P=0.0001)
- •Aged horses demonstrated a significantly greater insulin response to transportation stress compared to young horses (P<0.0001)