Selenium (Se) is an important part of the enzyme glutathion peroxydase which takes part in the protection of lipids in cell membranes.
Selenium deficiency may lead to muscle dysthrophy, newborn foals with poor ability to suckle, and many other pathological conditions.
Many areas in the world have selenium deficient soils where selenium supplementation is required for successful animal production.
Selenium is added to most concentrate and mineral mixes for horses. Look for feeds with a high selenium content in your feed list.