Rules in the USA Horses are not tested for Steriods in the USA. If a trainer has a product that decreases the amount of time a horse takes to recover should he/she use it if legal? Steriods do just that. Like as in a humans they do not promote anything without work. They just let you workout more often. So the answer to your question was steriods used on the horse? Most likely however they do not make you run faster they just let you prepare to run faster.Natural development? No but within the rules. Quite "FRANKLY" if a trainer is not using the best avaible legal science he/she is behind the others who do. Therein lies the question. Again who is and who isn't?