Metabolic Syndrome in Healthy Ponies Facilitates Nutritional Countermeasures against Pasture Laminitis

Treatment of clinical laminitis usually fails to prevent some degree of persistent disability; thus, intervention should aim at avoiding risk factors and preventing the disease. Efficiency of intervention would be improved by identifying predisposed horses and ponies. A herd of 160 healthy ponies included 54 previously laminitic (PL) and 106 never laminitic (NL). Pedigree analysis was consistent with dominant inheritance partially suppressed in males. Blood analysis revealed higher plasma concentrations of insulin and triglycerides but not cortisol, glucose, or free fatty acids in the PL group. Proxies for insulin sensitivity and β-cell responsiveness, which were calculated from plasma insulin and glucose, indicated compensated insulin resistance in the PL group. A prelaminitic metabolic syndrome (PLMS) was derived statistically to have cut-off points for the 2 proxies, hypertriglyceridemia, and body condition score. It had a total predictive power of 78%. It identified 62 ponies with PLMS, and 98 as PLMS-free. Two months later, pasture starch concentration doubled, and 13 clinical cases of laminitis developed, 11 in the PLMS group and 2 in the PLMS-free group, giving an odds ratio of 10.4 (P = 0.0006). The PLMS can be used to identify predisposed ponies in need of special care; the efficiency of intervention would increase nearly 3-fold in the present case. It enables the design of new interventions suitable for testing. The PLMS also might influence market values.