Detection of the administration of 17 β ‐nortestosterone in boars by gas chromatography/mass spectrometry

17 β ‐Nortestosterone (17 β N) is illegally used in livestock as a growth promoter and its endogenous production has been described in some animals, such as adult boars. In this paper, the metabolism of 17 β N in boars has been studied by gas chromatography/mass spectrometry (GC/MS) in order to identify markers of the exogenous administration. Administration studies of intramuscular 17 β N laurate to male pigs were performed. Free, sulphate and glucuronide fractions of the urine samples were separated and the steroids present were quantified by GC/MS. 17 β N was detected in some pre‐administration samples. After administration, 17 β N, norandrosterone, noretiocholanolone (NorE), norepiandrosterone, 5 β ‐estrane‐3 α ,17 β ‐diol and 5 α ‐estrane‐3 β ,17 β ‐diol were detected in different fractions, being the most important metabolites, 17 β N excreted as a sulphate and free NorE. Samples collected in routine controls were also analyzed by GC/MS to identify endogenous compounds. 17 β N, norandrostenedione and estrone were detected in almost all the samples. No other 17 β N metabolites were detected. According to these results, the detection by GC/MS of some of the 17 β N metabolites described above, different from 17 β N, could be indicative of the exogenous administration of 17 β N to boars. Copyright © 2008 John Wiley & Sons, Ltd.