Scintigraphic evaluation of digital circulation during the developmental and acute phases of equine laminitis.
Authors: Trout, Hornof, Linford, O'Brien
Journal: Equine veterinary journal
Summary
# Editorial Summary: Digital Circulation in Equine Laminitis Using nuclear scintigraphy with technetium-99m tracers, Trout and colleagues monitored blood flow patterns in the feet of nine laminitic horses and eleven controls over the developmental and acute phases of disease, injecting radioactive markers into the arterial and venous systems to generate dynamic and static images of the whole foot and specific lamellar regions. Contrary to the prevailing hypothesis of the era, quantitative analysis revealed no reduction in total blood flow to the lamellae during either phase; instead, lamellar perfusion actually increased significantly, whilst peripheral foot regions showed a broader trend towards elevated flow. The enhanced lamellar circulation likely reflected either increased capillary perfusion or heightened arteriovenous shunt flow, suggesting that lamellar ischaemia—then a widely accepted mechanism in laminitis pathogenesis—was not the primary driver of acute disease onset. These findings fundamentally challenged the ischaemic model and redirected clinical thinking towards inflammatory and biomechanical mechanisms, making this work particularly valuable for practitioners seeking to understand why treatments targeting vasodilatation have shown limited efficacy in preventing acute laminitis. Further investigation into the nature of that increased lamellar flow and its relationship to lamellar dysfunction remains essential for refining both prevention and therapeutic strategies.
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Practical Takeaways
- •Lamellar tissue damage in acute laminitis is not primarily caused by lack of blood supply—other mechanisms (inflammatory, metabolic) should be investigated for treatment targets
- •The presence of increased blood flow to lamellae suggests hyperaemia and vascular shunting may play a role in laminitis pathophysiology, potentially guiding anti-inflammatory or vascular management strategies
- •Scintigraphic evaluation offers objective measurement of digital circulation patterns and can help differentiate between ischaemic and non-ischaemic causes of lameness in acute cases
Key Findings
- •No evidence of reduced total blood flow to the lamellae during developmental or acute phases of laminitis in 9 affected horses versus 11 controls
- •Total blood flow to lamellae showed statistically significant elevations in the acute laminitis group
- •Increased lamellar blood flow may result from elevated capillary flow and/or arteriovenous shunt flow rather than ischaemia
- •Study findings do not support lamellar ischaemia as the primary cause of acute equine laminitis