Induction of laminitis by prolonged hyperinsulinaemia in clinically normal ponies.
Authors: Asplin, Sillence, Pollitt, McGowan
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Landmark 2008 research by Asplin and colleagues demonstrated that sustained hyperinsulinaemia alone—independent of elevated blood glucose—can trigger laminitis in previously healthy ponies, challenging the historical assumption that laminitis in insulin-resistant animals results primarily from hyperglycaemia or digestive disturbance. Using a euglycaemic hyperinsulinaemic clamp technique, researchers maintained serum insulin at approximately 1036 microU/mL in five treatment ponies whilst keeping blood glucose normal, whilst four control ponies received saline; all treatment animals developed clinical and histopathological laminitis (Obel grade 2) across all four feet within 55.4 hours, with no systemic illness or gastrointestinal signs, whereas controls remained unaffected. This mechanistic finding isolates hyperinsulinaemia as a direct pathogenic factor in endocrinopathic laminitis, suggesting the laminar tissue itself—or the vascular and inflammatory cascades within the foot—responds to chronically elevated insulin signalling in ways that compromise lamellar integrity. For practitioners managing metabolic disease in horses and ponies, these findings underscore the critical importance of identifying and aggressively treating hyperinsulinaemia through early diagnostic testing (fasting insulin, oral glucose tolerance testing, or euglycaemic clamp), dietary modification, and exercise, potentially before clinical laminitis develops; waiting for overt laminitis signs represents a significant missed opportunity for prevention.
Read the full abstract on PubMed
Practical Takeaways
- •Early detection and aggressive management of hyperinsulinaemia should be a priority in endocrinopathic laminitis cases, as insulin itself appears causative independent of blood glucose levels
- •Insulin resistance and resulting hyperinsulinaemia may be a critical risk factor even in apparently healthy ponies, warranting baseline insulin screening for at-risk populations
- •This research strengthens the case for insulin-lowering strategies (diet management, exercise, medications) as primary prevention and treatment protocols for insulin-related laminitis
Key Findings
- •All 5 treatment ponies developed clinical and histological laminitis (Obel grade 2) within 72 hours (mean 55.4±5.5h) under prolonged hyperinsulinaemia with euglycaemia
- •Mean serum insulin in treatment group was 1036±55 microU/mL compared to 14.6 microU/mL in controls, demonstrating 70-fold elevation
- •None of the 4 control ponies developed laminitis despite identical saline infusion protocol
- •Hyperinsulinaemia induced laminitis independently of hyperglycaemia, gastrointestinal involvement, or systemic illness