Laminitis is a painful and debilitating condition of horses and ponies that has major economic and welfare implications. Anecdotal observations and the results of survey studies have indicated that most laminitis cases occur in horses and ponies kept at pasture (hence, the term pasture-associated laminitis). Risk for development of pasture-associated laminitis represents a dynamic interaction between animal predisposing factors (an insulin-resistant phenotype commonly termed equine metabolic syndrome) and environmental conditions, particularly the nonstructural carbohydrate (simple sugars, starches, and fructans) content of pasture forage. Countermeasures for avoidance of pasture-associated laminitis involve (1) mitigation of metabolic predisposition (insulin resistance and obesity) in high-risk horses and ponies and (2) dietary and pasture grazing management strategies that minimize exposure to the dietary conditions known to trigger laminitis in susceptible animals.