Myositis (Selenium-Tocopherol Deficiency) Syndrome

Disease Overview

Many regions of the United States produce selenium-deficient forage, including areas of the Pacific Northwest, the Great Lakes and the Eastern Seaboard. The clinical condition that results from a deficiency of selenium and vitamin E (which work together synergistically) is sometimes called “white muscle disease” or nutritional myodegeneration. This degenerative disease affects skeletal and cardiac muscle. Young, rapidly growing foals born to dams fed a diet low in selenium and vitamin E are most commonly affected, but this deficiency has been implicated in muscle problems in adult horses as well.