Plasma androgen concentrations in initial samples from spotted hyaenas immobilized with Zoletil (CI-744) reflect hormonal status estimated by GnRH challenge and immobilization stress response

Abstract

The use of single samples to assess the androgen status of animals can be problematic owing to extensive short-term fluctuations in the concentrations of these hormones. Thus, this study evaluated a number of estimates for both testosterone and androstenedione status in the spotted hyaena (Crocuta crocuta), namely, initial samples, the immobilization stress response and the response to exogenous GnRH administration, for their mutual consistency. This study found that in animals immobilized with Zoletil and maintained on halothane, all three estimates show a good consistency. Moreover, the large variance in androgen status reported here within the sexes explains earlier contradictory results, and implies that the debate concerning the sex-specific differences in plasma androgens is confounded by other variables such as the reproductive and social status of the individuals included in the analysis.