Noninvasive monitoring of adrenocortical activity in roe deer (Capreolus capreolus) by measurement of fecal cortisol metabolites

A method for measuring glucocorticoids noninvasively in feces of roe deer w as established and validated. The enzyme immunoassay (EIA) measures 11,17-d ioxoandrostanes (11,17-DOA), a group of cortisol metabolites. Such measurem ent avoids blood sampling and reflects a dampened pattern of diurnal glucoc orticoid secretion, providing an integrated measure of adrenocortical activ ity. After high-performance liquid chromatography, the presence of at least three different immunoreactive 11,17-DOA in the feces of roe deer was demo nstrated. The physiological relevance of these fecal cortisol metabolites t o adrenocortical activity was evaluated with an adrenocorticotropic hormone challenge test: cortisol metabolite concentrations exceeded pretreatment l evels (31-78 ng/g) up to 13-fold (183-944 ng/g) within 8-23 h. Starting fro m basal levels between 13 and 71 ng/g, a suppression of adrenocortical acti vity after dexamethasone administration, indicated by metabolite levels clo se to the detection limit, was obtained 36-81 h after treat ment, whereas u nmetabolized dexamethasone was detectable in feces 12 h after its injection . Fecal glucocorticoid metabolite assessment via EIA is therefore of use in the monitoring of adrenocortical activity in roe deer. In a second experim ent, capture, veterinary treatment, and transportation of animals were used as experimental stresses. This resulted in a 7.5-fold increase of fecal me tabolites (1200 +/- 880 ng/g, mean +/- SD) compared to baseline concentrat ions. The administration of a long-acting tranquilizer (LAT), designed to m inimize the physiological stress response, 2 days prior to a similar stress event led to a reduced stress response, resulting in only a 4-fold increas e of fecal metabolites (650 +/- 280 ng/g; mean +/- SD). Therefore, LATs sho uld be further investigated for their effectiveness in reducing stress resp onses in zoo and wild animals, e.g., when translocations are necessary. (C) 2001 Academic Press.