Any Steroid Experts?

[Fairmount1]

http://www.drf.com/news/new-york-bans-use-anabolic-steroid-stanozolol

Current regulations allow for the presence of those steroids at low levels, and the use of supplementary doses of those steroids is still allowed in horses in New York as long as the horse is on the vet's list, which would prohibit a horse from racing until the high levels drop to natural levels.
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Someone want to help me out here?  A horse goes on the Vet\'s List for any problem of such level warranting Vet List.  Trainer/vet/whomever administer enormous amounts of \"naturally occuring steroids\" (help me with what this includes? and how is it different from anabolic steroids?) and the horse builds enormous amounts of muscle, strength, speed, etc.  I wean the horse off the steroid until he reaches a level that is acceptable/natural level and he has solved whatever Vet List issue placed him in such category.  I race my horse and he wins.  Perfectly okay?  

And is my example plausible?  Or would the newfound muscle and strength go away as fast as the steroid level reduces to the acceptable level?  And also, will naturally occurring steroids allow you to build muscle the same as anabolic steroids?

Thanks.