Fecal cortisol metabolite analysis for noninvasive monitoring of adrenocortical function in the cheetah (Acinonyx jubatus)

A radioimmunoassay was validated fur quantifying excreted cortisol metaboli tes in cheetah (Acinonyx jubatus) feces. High-performance liquid chromatogr aphy analysis indicated that immunoreactivity was associated with a water-s oluble metabolite in fecal extracts from males and females. None of the imm unoreactivity corresponded with free cortisol or corticosterone but rather was associated with a more polar, unidentified metabolite. To determine the biologic relevance of excreted immunoreactive cortisol metabolites, cheeta hs were exposed to a variety of situations anticipated to increase cortisol secretion. First. to assess acute changes in adrenal activity. adrenocorti cotropic hormone (ACTH; 400 IU i.m.) was administered to two adult males an d two adult females. Pre-ACTH baseline serum cortisol and fecal cortisol me tabolite concentrations varied among individuals. Serum cortisol concentrat ions were elevated above baseline within 10 min of ACTH injection. followed by corresponding increases in fecal cortisol metabolite concentrations (69 0-4,194% above baseline) 38 hr Inter in three of four cheetahs. In the four th cheetah. a smaller increase (334% above baseline) in fecal cortisol meta bolite excretion was observed 90 hr after ACTH injection. Seven cheetah fem ales also were subjected to a variety of potentially stressful manipulation s. including immobilization, translocation. and introduction to a male to a ssess the ability of this technique to detect physiologic changes in adrena l activity. Increased fecal corticoid metabolite excretion was observed 21- 72 hr after exposure to these exogenous stressors. Results indicate that ad renocortical activity can be monitored noninvasively in the cheetah through analysis of these metabolites. This technique could be valuable for evalua ting, and thus optimizing, environmental and management conditions and for investigating the role of stress: in disease pathogenesis and the usually p oor reproductive performance of this species in captivity.