Estradiol cypionate is an esterified estrogen that is more potent and has a longer half-life than the predominant naturally occurring estrogen, estradiol 17 beta. Estradiol cypionate is absorbed more slowly than estradiol itself, and for that reason, can be administered less often. Estradiol Cypionate is commonly prescribed for improving uterine tonicity, maintain jump mares, create teasers from geldings, pretreatment before giving sulperide or domperidone to anovulatory mares (premature udder development), pregnancy maintenance over an extended period of time or relax stifle.