A non- inflammatory degenerative muscle disease affecting both skeletal and heart muscle in foals from birth to 11 months age. Affected parts of the muscle appear light or white in colour at post -mortem examination and fat stores may be yellow in colour. Clinical signs include muscular weakness, failure to stand and suckle, heart failure and unthriftiness. Blood biochemistry testing may reveal elevated muscle enzymes, AST, and CK and depressed GSH-Px.
The cause may be either Selenium deficiency, Vitamin E deficiency or a combination of the two. As Vitamin E requires Selenium for its activity it is likely that a deficiency of Selenium is the primary cause of the disease, though treatment may involve high dose Vitamin E as well as Selenium supplementation. When foals are affected, the Selenium and Vitamin E status of their dams should be evaluated. Several areas of Australia and New Zealand are known to have Selenium deficient soils and Selenium is commonly included in manufactured feeds for stud use.