DIETARY THERAPY OF EQUINE POLYSACCHARIDE STORAGE MYOPATHY

A diagnosis of equine polysaccharide storage myopathy (EPSM) was made in six non-Quarter Horse related breeds. Clinical signs in affected ho rses included exertional rhabdomyolysis (four horses), stiff pelvic li mb gait (three horses), poor performance and lack of energy (three hor ses), and overt muscle atrophy (one horse). After 2 to 3 months of die tary therapy all horses showed moderate to marked improvement of perfo rmance, despite frequent markedly increased post-exercise concentratio ns of serum muscle enzymes. Blood concentrations of Vitamin E and sele nium determined before and during the dietary trial did nor. support t he hypothesis that a deficiency of Vitamin for selenium was responsibl e for the myopathy in these horses. A carbohydrate metabolic defect in muscle of affected horses is supported by these results, which indica te that muscle function in horses with EPSM may be markedly improved b y feeding a low carbohydrate; high fat, and high protein diet.