Evaluating adrenal activity in African wild dogs (Lycaon pictus) by fecal corticosteroid analysis

A noninvasive corticosteroid hormone monitoring technique was validated for use in African wild dogs (Lycaon pictus). The double-antibody 125I radioimmunoassay for corticosterone was validated by demonstrating parallelism between serial dilutions of wild dog fecal extracts and the standard curve, recovery of corticosterone added to fecal extracts, and the time course of fecal corticoid excretion after an exogenous adrenocorticotropic hormone (ACTH) challenge. All feces were collected from three female and two male African wild dogs for 72 hr before and 144 hr after i.m. injection of long-acting ACTH (Acthar Gel, 400 IU). Fecal corticosterone immunoreactivity increased 10-30-fold within 24 hr of ACTH administration in all individuals, with peak concentrations from 1,200-8,000 ng/g. High-pressure liquid chromatography analysis revealed that >90% of all corticosterone immunoreactivity was associated with a single peak that exhibited intermediate polarity relative to cortisol and corticosterone reference tracers. Fecal corticosterone immunoreactivity appears to reflect adrenal activity in the African wild dog and, therefore, may be useful for evaluating stress. From a conservation perspective, these techniques can complement in situ and ex situ research studies designed to evaluate how environmental conditions and management strategies affect overall animal health.