Measuring physiological stress reactions through the quantification of plasma
cortisol often involves physically restraint, which acts as a stressor itself.
Here, we present the validation of a non-invasive method for assessing
adrenocortical activity as an indicator of stress in the bat-eared fox (Otocyon
megalotis). By conducting an adrenocorticotropic hormone (ACTH) challenge,
we examined the suitability of three enzyme immunoassays (EIAs) detecting
11,17 dioxoandrostanes (11,17-DOA) as well as faecal glucocorticoid
metabolites (fGCM) with a 5β-3α-ol-11-one (3α,11oxo-CM), or 11,17,21-
trihydroxy-4-ene-20-one structure (cortisol), respectively, for monitoring
stress-related physiological responses in male and female bat-eared foxes.
Our results suggest that the cortisol EIA seems most suitable for measuring
fGCMs in this myrmecophageous mammal. Using the cortisol EIA, we
compared fGCM concentrations of three populations of foxes. Only one population experienced a sudden change in social environment and the assay
appeared to effectively detect the resulting increase in stress hormone levels.
Therefore, the identified EIA is effective at detecting intraspecific variation in
fGCM levels, and hence a useful tool to evaluate physiological stress
responses in this species.