Myodegeneration and suspected selenium/vitamin E deficiency in horses.

The clinical, macroscopic, and microscopic features of 10 isolated cases of myodegeneration in foals were compared. Low values for selenium and vitamin E content were found in the hay and oats from one breeding stable. Serum selenium concentrations in mares at this stable were also low. Creatinine phosphokinase and serum glutamic oxaloacetic transaminase activities were increased in 2 young foals at this stable; in 1 of these foals, both enzymatic activities were markedly reduced after treatment with vitamin E and selenium. Nutritional myodegeneration was suggested as a diagnosis in this stable, on the basis of the histologic findings, feed analyses, serum selenium values, response to treatment, and enzymatic determinations. Nine other isolated cases of nutritional myodegeneration were tentatively diagnosed on the basis of macroscopic and microscopic findings and the young age of the animal. The gross lesions included pale areas in the myocardium and skeletal muscle masses. Histologically, lesions were characterized by fragmentation and hyaline and granular changes in swollen muscle fibers in widely distributed skeletal muscle masses.