Selenium and vitamin E in horses.

A survey of selenium and vitamin E concentrations in horses was conducted at four breeding farms in New York. There were no significant changes in mean blood selenium concentrations in horses at the three sampling dates whereas vitamin E concentrations underwent seasonal fluctuations. The mean blood selenium concentration in this survey for horses fed local feed was 7.7 microgram/dl. Horses fed commercial feed had a mean blood selenium concentration of 15.6 microgram/dl. A 0.94 correlation coefficient was found between blood glutatione peroxidase activity and blood selenium concentrations in horses. The effect of oral and parenteral selenium administration on blood selenium concentrations and blood glutathione peroxidase activity was also investigated. Oral supplementation of 1 mg selenium per day increased blood selenium concentrations above levels associated with myodegeneration in horses and foals. Parenteral supplementation trials with mares at late gestation indicate that only limited amounts of selenium cross the placental barrier. Parenteral supplementation of mares during gestation and lactation or supplementation of foals beginning at birth will increase blood selenium levels in foals above that associated with selenium/vitamin E deficiency.