Current concepts on the pathophysiology of pasture-associated laminitis.
Authors: Geor
Journal: The Veterinary clinics of North America. Equine practice
Summary
# Editorial Summary: Pasture-Associated Laminitis Pathophysiology Pasture-associated laminitis accounts for the majority of clinical cases seen in practice, yet the precise mechanisms linking grazing to lamellar failure remain incompletely understood. Geor's review synthesises epidemiological evidence and current pathophysiological knowledge to establish that horses and ponies with metabolic phenotypes—particularly insulin resistance and equine metabolic syndrome—face substantially elevated risk when grazing pastures high in rapidly fermentable nonstructural carbohydrates (fructans, simple sugars, and starches). The proposed mechanism involves hindgut carbohydrate overload triggering systemic inflammation, which subsequently initiates lamellar-specific inflammatory cascades characterised by leukocyte infiltration, immune cell activation, and destruction of lamellar epithelium and extracellular matrix. For practitioners, this framework emphasises the critical importance of pasture management—particularly restricting access during high-risk periods (spring growth, drought stress, and autumn flush)—combined with pre-grazing metabolic assessment to identify at-risk individuals before clinical laminitis develops. Understanding these risk factors enables more targeted prevention strategies than treating acute cases, with particular attention warranted toward monitoring insulin dynamics and body condition in susceptible animals.
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Practical Takeaways
- •Assess pasture forage quality and carbohydrate content in horses with metabolic risk factors; consider strip grazing, hay nets, or dry lot management during high fructan periods (spring, autumn)
- •Screen at-risk horses (overweight, insulin-resistant, or with abnormal insulin dynamics) before turnout to identify those requiring modified grazing management to prevent laminitis
- •Understanding the inflammatory cascade from carbohydrate overload helps frame prevention and early intervention strategies focused on limiting fermentable carbohydrate intake rather than treating advanced lamellar damage
Key Findings
- •Most laminitis cases occur in horses and ponies kept at pasture, particularly under conditions favoring accumulation of rapidly fermentable nonstructural carbohydrates (fructans, simple sugars, starches)
- •Animals with equine metabolic syndrome phenotype (insulin resistance, abnormal insulin dynamics, obesity) are at highest risk for developing pasture-associated laminitis
- •Systemic inflammatory response from hindgut carbohydrate overload initiates lamellar inflammation with leukocyte infiltration and activation, contributing to lamellar epithelium and extracellular matrix destruction