We might be feeding our horses too well, at least as far as predisposing them to laminitis. Ray J. Geor, BVSc, PhD, Dipl. ACVIM, professor and chair of the Department of Large Animal Clinical Sciences at Michigan State University, spoke about controlling nutritional risks in pre- and post-laminitic horses at the Sept. 17-18 Laminitis West Conference in Monterey, Calif.

"All of us recognize that horses evolved to consume roughage," said Geor. "Despite the fact that we're all well aware of that, we tend to feed horses somewhat differently. We often feed them starch-based meals (cereal grains and sweet feeds, for example) or allow them to graze 'improved pastures' that are rich in sugars."

Pastures designed for dairy cattle, for example, have a much higher carbohydrate content than is ideal for horses. Overconsumption of these types of feeds can lead to laminitis, especially in horses and ponies with equine metabolic syndrome (EMS). Changes in pasture, like that which occurs in spring and fall when the water-soluble carbohydrate (WSC) and starch contents rise, pose the greatest risk for an episode of laminitis.

Consumption of pasture rich in WSC can markedly disturb the microbial population of the horse's hindgut and trigger events that lead to the development of laminitis. Yet not all horses turned out on WSC-rich pasture will develop laminitis. Geor explained that horses and ponies with features of EMS appear to be more susceptible to laminitis under these conditions. Clinical features of EMS include obesity and/or regional accumulations of excessive fat (e.g., a cresty neck) and insulin resistance. In these animals, exaggerated increases in blood insulin after feeding might contribute to laminitis