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 . 
Progestins are steroid hormones that are typically prescribed to postpone heat cycles or alleviate false pregnancies in female dogs and treat benign prostatic hypertrophy in male dogs. They may also be used for some types of skin problems or to modify aggressive behavior. Megestrol acetate and medroxyprogesterone are the most commonly used progestins in dogs. Potential side effects include increased thirst and appetite, behavioral changes, mammary gland enlargement, and an increased likelihood of developing diabetes mellitus, acromegaly (a hormonal disease that causes enlargement of the head), Cushing’s disease, uterine infection (pyometra), reproductive disorders, and some types of cancer.