Selenium Supplement for Horses

Selenium is an important trace mineral that occurs naturally in most parts of the country but in those areas where the soil is deficient, it's often a good idea to provide a supplement. Performance horses and horses used for breeding purposes are especially vulnerable to selenium deficiencies that could affect recovery from stress or vigorous workouts or in the case of mares, the health of their foals.

  1. An Important Trace Mineral

    • Selenium is a trace mineral that aids in cell growth and function and is often fed as a means of helping a horse recover after a workout to improve his immune system and encourage a healthy thyroid. It is also important as an antioxidant that helps rid the body of free-radicals, the oxidative by-products of the chemical reactions that produce energy but which in large doses can damage cell membranes.

    How a Horse Gets Selenium Into His Diet

    • A horse naturally gets selenium from plants that obtain it from the soil, but some areas of the country are selenium-deficient. These areas include parts of the Pacific Northwest, the Great Lakes and New England, extending downward into Florida. In the case of selenium-deficient areas, a supplement may be needed.

      The recommended level of selenium for the average-size horse is 3 mg per day. Check feed labels for selenium additives and calculate according to your region whether or not a supplement may be needed. In figuring out selenium levels, always take into consideration feed, such as hay or grain, that is imported and that may have been grown in an area richer in selenium than what your horse is used to eating.

    Advantages of Organic Over Inorganic Selenium

    • Organic selenium has the advantage over inorganic selenium of being metabolized quickly to improve immunities and boost recovery from stress. Organic selenium also helps a mare pass higher antibody levels to her foal through her milk and is safer to handle because it cannot be absorbed through the skin.

      Inorganic selenium is derived from copper mining and cannot be fully metabolized or stored in the muscle, colostrums or milk protein. In short, horses fed inorganic selenium (sodium selenite and selenate) can still acquire a deficiency due to unreliable blood levels of the mineral and its inability to be stored within the body.

    Selenium Deficiency

    • Selenium deficiency may result in a degenerative muscle disease known as rhabdomyolysis, or tying up. Symptoms of tying up are muscle cramps, stiffness, sweating and increased pulse rate in horses and in foals, failure to suckle. A condition known as white muscle disease can also occur, affecting the skeletal and cardiac muscles of foals who are nursing from dams that are deficient.

    Selenium Toxicity

    • Selenium toxicity, or too much selenium in the diet, can result in hair loss in the mane and tail, cracked hooves, lameness, excess salivation and respiratory failure. Severe cases may involve blindness, labored breathing, respiratory failure, muscle tremors and death.