The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine . 
Winstrol is a brand name of the synthetic anabolic steroid, stanozolol. Although no longer available in the . under the name of Winstrol, generic versions of stanozolol can still be found. Stanozolol is similar to testosterone and commonly used by veterinarians on debilitated animals (especially dogs and horses) to improve muscle growth, trigger red blood cell production, increase bone density and enhance appetite. It's approved by the . Food and Drug Administration (FDA) for treating anemia and hereditary angioedema (swelling of blood vessels) in people, although a prescription is needed. Winstrol (stanozolol) is a banned performance-enhancing drug, but still used widely by track and field athletes as well as bodybuilders — usually illegally. You should take stanozolol only with the permission and under the care of a physician.
With regard to Curlin’s performance in Dubai, it should be noted that the horses he faced over there were incredibly sub-par. indicative of the state of the older male dirt handicap division this year. Both “races” were nothing more than well paid public workouts. With the retirement of so many of last years top 3 year olds including Street Sense, even a temporally steroid free Curlin could beat the plugs he faced there in a $4M race. This was a smart tactical move by his connections since the BC is in California this year on a synthetic surface in a state that will soon ban the presence of anabolic steroids in a horses’ blood on race day. IMO, there is little chance Curlin will race in the BC classic. Steve Assmussen, Curlin’s trainer and Rick Dutrow, Big Winstrol’s trainer, both annually vie for the title of top “super drug trainer”. Just Google their names if you want to read about their sordid histories, replete with many suspensions for administering performance enhancing drugs to their horses.