Laminitis is a disease in which the laminae (interdigitating tissues connecting the hoof wall and coffin bone) of a horse’s feet become inflamed. Sugar fructans are energy produced and used by grass. When the horse consumes enough of these fructans, they stimulate an overgrowth of bacteria in the horse’s large intestine. These bacteria release toxins, which travel to the horse’s foot through the bloodstream. Here, they can damage the laminae and small blood vessels.

Laminitis is not only a seasonal concern. It also can be caused by certain drugs, infection, systemic illness, Cushing’s disease, concussion from riding on hard surfaces, excessive weight bearing due to injury, stress from long distances, and high insulin levels.

When there are sunny days and cool nights, grass produces and stores extra sugar fructans. During other seasons, the grass will use most of its fructans, so laminitis is less of a concern.