Equine laminitis: comparative histopathology 48 hours after experimental induction with insulin or alimentary oligofructose in standardbred horses.
Authors: de Laat, van Eps, McGowan, Sillence, Pollitt
Journal: Journal of comparative pathology
Summary
# Editorial Summary Two distinct triggers of equine laminitis—hyperinsulinaemia and carbohydrate overload—produce remarkably similar structural damage to the lamellae within 48 hours, though with notable differences in inflammatory intensity. De Laat and colleagues examined lamellar tissue from standardbred horses with experimentally induced insulin-driven laminitis (via euglycaemic hyperinsulinaemic clamp) and oligofructose-induced laminitis alongside healthy controls, measuring changes in secondary epidermal lamellae morphology and quantifying white blood cell infiltration using calprotectin immunolocalisation. Both laminitic groups exhibited significantly lengthened and narrowed secondary lamellae and elongation of the primary lamellae's axial terminus compared to controls; critically, the structural changes were indistinguishable between the two induction methods, whilst calprotectin expression differed markedly (moderate in hyperinsulinaemic horses versus marked in oligofructose-treated horses), indicating that carbohydrate overload triggers more aggressive leucocyte emigration. This finding suggests that whilst insulin-related and alimentary laminitis share a common final pathway of lamellar mechanical failure, the inflammatory mechanisms driving tissue damage may differ substantially—information that could eventually guide therapeutic strategies tailored to the initiating cause rather than assuming one-size-fits-all anti-inflammatory approaches are equally effective across different laminitis aetiologies.
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Practical Takeaways
- •Insulin-induced and carbohydrate-overload laminitis produce similar structural damage to lamellar tissues within 48 hours, suggesting common downstream pathological mechanisms despite different triggers—management approaches targeting lamellar support may be broadly applicable.
- •The lesser inflammatory response in hyperinsulinaemia compared to oligofructose overload at 48 hours indicates different disease kinetics; early intervention strategies may need to be tailored to the trigger mechanism.
- •Histopathological changes at 48 hours include lengthening and narrowing of lamellae—these morphometric changes could serve as objective indicators of early laminitis severity in clinical or research settings.
Key Findings
- •Both insulin-induced and oligofructose-induced laminitis produced comparable lengthening and narrowing of secondary epidermal lamellae (SELs) and elongation of primary epidermal lamellae (PELs) axial tips at 48 hours post-induction.
- •Secondary epidermal lamellae were significantly longer (P<0.05) and narrower (P<0.05) in treated horses compared with controls, with no significant difference between the two treatment groups.
- •Calprotectin expression indicated moderate leucocyte infiltration in hyperinsulinaemic horses but marked infiltration in oligofructose-treated horses, suggesting different inflammatory magnitudes despite similar structural changes.
- •Laminitic lesions at 48 hours included epidermal basal cell rounding, mitosis, apoptosis, and altered lamellar architecture consistent across both induction methods.