Hyperinsulinaemia increases vascular resistance and endothelin-1 expression in the equine digit.
Authors: Gauff F, Patan-Zugaj B, Licka T F
Journal: Equine veterinary journal
Summary
# Editorial Summary: Hyperinsulinaemia and Digital Vascular Changes in Horses Researchers investigated whether the insulin resistance–laminitis connection operates through a vascular mechanism by examining how elevated insulin affects blood flow and tissue chemistry in isolated equine digits. Using an extracorporeal perfusion model, they perfused five hyperinsulinaemic digits (mean plasma insulin 142 ± 81 μIU/ml) and five control digits for 10 hours whilst measuring perfusion pressure, metabolic markers and vascular resistance. The hyperinsulinaemic group demonstrated significantly higher vascular resistance (2.04 ± 1.13 versus 1.31 ± 0.55 mmHg/ml/min, P<0.01), alongside substantially increased endothelin-1 (ET-1) expression in lamellar blood vessels and nerve fibres—findings that mirror observations in insulin-resistant rodent models. These results suggest that elevated insulin directly impairs digit perfusion through endothelial dysfunction, potentially explaining why insulin-resistant horses face heightened laminitis risk and supporting the rationale for aggressive insulin management in at-risk animals.
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Practical Takeaways
- •Hyperinsulinaemia may directly increase vascular resistance in the equine foot through ET-1 overexpression, providing a mechanistic link between insulin resistance and laminitis susceptibility
- •Management of insulin-resistant horses should emphasize glycaemic control to prevent vascular changes in digital tissues that could precipitate or worsen laminitis
- •Early detection and treatment of insulin resistance may help prevent the pathological vascular changes in the foot before clinical laminitis develops
Key Findings
- •Hyperinsulinaemic perfusion increased mean vascular resistance to 2.04 ± 1.13 mmHg/ml/min compared to 1.31 ± 0.55 in controls (P<0.01)
- •ET-1 expression was significantly more prominent in lamellar vessels and nerve fibres of hyperinsulinaemic digits compared to controls
- •Hyperinsulinaemic digits showed increased numbers of vessels with open lumens, widened secondary epidermal lamellae, and oedema formation
- •Mean insulin concentration achieved in hyperinsulinaemic group was 142 ± 81 μiu/ml over 10-hour perfusion period