Some steroid hormones are involved in regulation of growth and thereby are useful in animal husbandry to improve weight gain and feed efficiency. In some countries like the USA or Canada the use of growth promoters is approved. Due to proven side effects for consumers the use of anabolic substances is forbidden in the EU. To uncover the abuse of anabolic agents, hormone residues are detected. With this approach only known substances can be discovered. To enable an efficient tracing of unknown misused anabolic substances it is necessary to develop new technologies to screen for a broad range of illegal drugs including newly designed xenobiotic anabolic agents. In this thesis the potential of verifying physiological effects caused by anabolic agents has been proved. Physiological changes were monitored by determining changes in gene expression that are induced by anabolic steroids in different tissues. Expression changes of multiple genes in blood and bovine vaginal smear could be quantified. Biostatistical tools were successfully used to distinguish treated and untreated animals by involving all significantly regulated genes.