We tend to associate springtime with laminitis, but fall is also a high risk for many horses.

Two decades ago, it was shown that laminitis in some areas correlates with a rise in pasture fructan levels and that tubing a horse with large amounts of fructan can induce laminitis. The fructan theory of pasture laminitis was born.

However, association is not causation. We now have many studies, including an excellent 3-year prospective study by Drs. P.A. Harris, J. Elliott and N.J. Menzies-Gow (2016), clearly showing high insulin is the conclusive risk factor for pasture laminitis.

Fructan is not digestible in the horse’s small intestine and does not cause an insulin rise. It causes laminitis by the same method as the “horse broke into the feed room.” It’s rapidly fermentable, causing hind gut acidosis, bacterial product leakage across the damaged intestinal wall and a systemic inflammatory response.

Furthermore, the fructan type used to induce laminitis was chickory root inulin, while grasses primarily have Levan, a more complex and slowly fermenting form. The amount of chickory inulin that…