Ahstlnct As m other sports, the use of anabohc agents 1s not pernutted m Greyhound Racmg Currently, there IS httle data avadable on the metabobsm of steroids m the racmg greyhound In the present study, the normal unnary steroid profile has been estabbshed m greyhounds whtch are actively bemg tramed The excretion of radto labelled and stable lsotoptcally labelled testosterone was cxammed to provtde a greater understandmg of the produmon, turnover and excretton m the ammals The pharmacokmetrcs of nandrolone (19-nortestosterone) was also exammed It was noted that the levels of naturally occurrmg steroids m greyhound urme are far lower than m humans and It was -cult to demonstrate the presence of any steroid m urme except by GC-MS m the selected Ion recorded mode There also exists a sex dtierence between dogs and bitches arlth corkostend levels bemg h&er III the bitch than the dog In parallel to approaches now bemg suggested for other sports, the levels of spec& endogenous steroids were exammed It was noted that although the levels of endogenous sterouis were depressed followmg the dosmg of an anaboltc agent, no -cant changes m the ratms of endogenous steroids were noted Kcywordr Gas chromatography, Mass spectrometry, Anabohc steroids, Ammal samples, 19_Nortestosterone, Greyhound racmg