Iodine Is Essential to a Healthy Hair Coat
Iodine controls the production of thyroid hormones, which are necessary for optimal health. Iodine deficiency can cause a dry, lusterless coat and patchy or diffuse hair loss. The NRC (National Research Council) estimates that the iodine requirement of horses is 0.1-0.6 mg/kg of the total diet. Grass and hay contain very small amounts of iodine. Some plain grains contain more iodine, but most horses get iodine from trace mineralized salt or a coat and hoof supplement.