Evaluation of boldenone undecylenate as an anabolic agent in horses.

THE PARENTERAL ADMINISTRATION of testosterone and other steroids to castrate dogs, rats and intact human males has been reported to increase gains in body weight and nitrogen retention (3, 5, 6) but in addition to the anabolic effects, there were undesirable androgenic side effects. In efforts to find compounds with improved efficiency and reduced side effects, many steroids that possess high anabolic activity and low androgenic activity have been synthesized (1, 7) and some are available as anabolic agents to the medical profession. In veterinary practice an anabolic steroid would be of value in restoring weight losses in animals, particularly horses debilitated from overwork, unthriftiness, or anorexia. The difficulties of conducting adequately controlled studies with such animals have resulted in many reports on restoration of weight loss that are based on clinical impressions rather than on well-designed experimental trials with adequate controls. The present experiments were conducted to determine the effects in horses of boldenone undecylenate (17 ,-hydroxyandrosta-1, 4-dien3-one, 17-(10-undecenate)),' a potent, longacting anabolic steroid. The parameters studied were weight gain, nitrogen retention, hemoglobin concentration, hematocrit, and blood serum levels of calcium and phosphorus.