Functioning of selenium (Se) in horses

Selenium has an important antioxidant function in the body as it is a component of glutathione peroxidase (one of the most important antioxidants). For this reason, it is seen together with Vitamin E as an important nutrient to eliminate free radicals.

Se

Trace element

Antioxidant function

• Against abnormal cell growth

But selenium is involved in many more functions in the body, namely:

• Fertility of mare and stallion

• Protection of heart and skeletal muscles against oxidative stress

• Protection of liver against oxidative stress

• Modulating and regulating cell growth proteins (against abnormal cell growth)

For foals, a selenium deficiency is more serious than for adult animals. The foal gets selenium through the mother's milk. A deficiency can cause a foal to develop White Muscle Disease, which is a degeneration of heart and skeletal muscles.

Selenium is mainly found in muscles, bones, and skin. With an excess of selenium, it is stored in the liver and kidney tissues.

Selenium poisoning

In principle, most horses receive enough selenium through normal feed. It is therefore wise to be cautious in providing extra selenium. Selenium poisoning can occur at any age, in any breed, and gender. It is usually seen in horses grazing on grass and receiving extra selenium supplementation. Exceeding the supplement dose is also a cause of selenium poisoning.

In cases of acute selenium poisoning, the horse becomes blind and experiences digestive issues, lung problems, heart, and kidney problems. In cases of chronic selenium poisoning (prolonged intake of excessive selenium), hoof problems develop, starting as lameness and worsening over time. The hooves will start cracking within a few days and recover poorly (often starting with the hind hooves). The hair becomes rougher and there is hair loss around the neck and tail.

Horses with selenium poisoning should be given a diet very low in selenium but high in protein and high-quality feed. These horses also require good hoof care, unfortunately, recovery takes months.

For this reason, be cautious when supplementing selenium. Does your horse need extra Vitamin E? Then choose a supplement without added selenium. Consider having a blood test done by a veterinarian first to determine if your horse is deficient in selenium.