A myodegeneration most frequent in calves and lambs whose dams have been fed during gestation or longer on feeds, especially legumes (Fabaceae), grown in certain areas where selenium is either deficient or unavailable in the soil. It has been recorded in many countries. It has been produced experimentally in several species of animals on low-selenium intake. A similar myopathy occurs naturally in goats, deer, foals, and dogs but proof of the etiology is lacking.