The pretty, lush grasses that green the countryside after rain is young, tender, and very tasty for a horse. Unfortunately, these young grasses are also low in the fibre that horses need and are high in the soluble carbohydrates that can upset the sensitive microbiotic balance in a horse's gut. Since horses are natural grazers, they need a diet high in fibre such as that found in long-stemmed, mature forage grasses.

Young grasses are higher in soluble carbohydrates, and large amounts of these carbohydrates can overload the gut, disturbing the balance of natural bacteria. As large numbers of natural gut bacteria die, they release a surge of a bacterial toxin called endotoxin. Endotoxin then gets into the bloodstream, where it can travel to the vessels of the feet and induce laminitis, especially in horses that are predisposed, such as overweight horses, horses with a previous history of laminitis, and horses with Cushing's disease.

To prevent this problem don't over fertilize, and don't allow grasses to go to seed. Some grasses, form seed heads quickly and horses will graze and pick for these tasty, high-carbohydrate seeds.

If this type of management is not feasible, keep horses from young green grasses in spring, when the grasses are most rich in carbohydrates. It can be difficult to keep horses from eating these grasses, but confining horses to a dry lot is one option. If a horse is let out to a green pasture, a muzzle can keep it from grazing the sweet grasses.

As grasses mature and become more "stemmy," their fibre content increases and their carbohydrate content drops, thus the risk of problems decreases as summer approaches.

For more information about this issue, contact your local equine veterinarian.