White muscle disease in sheep is caused by deficiency of which nutrient?

• A. Vitamin E deficiency
• B. Selenium deficiency
• C. Iodine deficiency
• D. Calcium deficiency

Answer: (B)

White muscle disease is driven by a lack of an antioxidant nutrient that protects muscle cells from oxidative damage, most classically selenium. Selenium is a key part of the enzyme glutathione peroxidase, which helps neutralize harmful peroxides in muscle tissue; when selenium is deficient, this protection fails, leading to degeneration of skeletal and cardiac muscles and resulting weakness and stiffness in lambs. Vitamin E also supports this protection and can contribute to the same disease when deficient, but selenium deficiency is the hallmark nutrient implicated in white muscle disease. Iodine deficiency affects thyroid function and growth, while calcium deficiency causes hypocalcemia and tetany—neither produces the muscle pathology seen in this condition.