The effect of weightbearing and limb load cycling on equine lamellar perfusion and energy metabolism measured using tissue microdialysis.
Authors: Medina-Torres C E, Underwood C, Pollitt C C, Castro-Olivera E M, Hodson M P, Richardson D W, van Eps A W
Journal: Equine veterinary journal
Summary
# Editorial Summary Lamellar perfusion changes are suspected to play a crucial role in supporting limb laminitis development, but direct evidence of how weightbearing patterns affect this tissue's metabolic environment has been limited. Using microdialysis probes implanted in the foot lamellae of nine horses, researchers systematically measured glucose, lactate, pyruvate and urea concentrations under different loading conditions: unilateral weightbearing, enhanced static load cycling, reduced activity (via sedation), and walking. Walking and increased limb load cycling both produced significant improvements in lamellar metabolic markers—specifically elevated glucose and pyruvate with reduced lactate:glucose ratios—indicating enhanced perfusion and better oxygenation, whilst unilateral weightbearing for one hour and sedation-induced immobility failed to produce measurable lamellar changes despite altered loading mechanics. The findings suggest that frequent cyclical limb movement, rather than simply maintaining weightbearing, is the critical driver of lamellar perfusion, which has direct implications for managing at-risk horses: promoting regular movement (including controlled exercise and mobilisation) may be more protective against supporting limb laminitis than static positioning, though further research is needed to definitively establish the hypoperfusion mechanism in disease development.
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Practical Takeaways
- •Maintaining regular limb load cycling and movement (especially walking) is essential for lamellar perfusion and may help prevent supporting limb laminitis
- •Short-term static weightbearing alone may not compromise lamellar perfusion as previously feared, but prolonged immobility and reduced movement cycles should still be avoided
- •Therapeutic strategies should focus on encouraging movement and load-cycling rather than attempting to reduce weightbearing on affected limbs
Key Findings
- •Enhanced static limb load cycling and walking increased lamellar glucose and decreased lactate:glucose ratio, indicating improved perfusion
- •One hour of unilateral weightbearing did not produce detectable changes in lamellar perfusion despite theoretical concerns
- •Sedation-induced reduction in limb load cycling frequency did not significantly alter lamellar perfusion markers despite decreased movement
- •Limb load cycling frequency, particularly during walking, appears critical for maintaining lamellar tissue perfusion and aerobic metabolism