Myos Canine Muscle Formula powered by Fortetropin® is an all-natural composition made from fertilized egg yolk that has been clinically proven to help build muscle and reduce the rate of muscle loss due to aging or injury.Veterinarian Recommended. Veterinarians reported that older dogs engaged in more physical activity after consuming Fortetropin® and resumed certain activities that were thought to have stopped because of age.Fortetropin® is all about muscle health but it also contains many essential amino acids, vitamins and minerals that support healthy skin, a shiny coat, bone health, cognitive health and improved vision!