Double-Blind Placebo-Controlled Vitamin E or Selenium Supplementation of Sport Horses with Unspecified Muscle Problems. An Example of the Potential of Placebos1,2

Because deficiencies of vitamin E and selenium may cause nutritional myopathy (1), German sport riders often presume that problems with their horses such as unresponsiveness or stiM back (back muscles do not relax and contract in the rhythm of the movement but remain permanently contracted, a condition that impairs the movements of the horse and gives the rider a very bumpy and uncomfortable ride) are caused by problems of muscle metabolism and may be alleviated by supplementation of extra vitamin E and/or selenium. All horses had rider-perceived "muscle problems"; no horse was lame or had a condition that needed veterinary treatment rather than nutritional supplementation. The following 28 potential problems were listed: excessive sweating, rhythm disunited, excess warm-up time, responsiveness, disobedience, swishing of tail, bucking, rearing, grinding of the teeth, asymmetric tail, head shaking, turning of head, disunited canter (left foreleg and right hindleg leading, this gait twists the hack of the horse and gives the rider an extremely uncomfortable ride), too self-confident, stumhling, protruding tongue, not sensitive to aids (i.e., standardized signals from the rider with legs, weight, and rains), sptxiking (shying at things in the environment), stiff or rounded hack, sluggish, no concentration, too "hot" (wants to go too fast), fretful mouth, unwilling to obey aids, not taking the hit, slow reactions, behind the bit (rounds his neck too much), too little tension.