Faecal cortisol metabolites as an indicator of adrenocortical activity in farmed silver foxes (Vulpes vulpes)

Abstract Measuring glucocorticoid metabolites in faeces has proven a useful, non-invasive method to monitor adrenocortical activity in several farm and wild species. Unlike plasma cortisol, whose sampling requires restraint and blood draws, faecal cortisol metabolites (FCM) may be particularly suitable for farmed silver foxes as these animals are sensitive to handling by humans. Prior to using FCM as a potential indicator of stress in silver foxes, however, a proper physiological and/or biological validation is required. Here, we determined FCM concentrations in 30 silver foxes (10 adult vixens, 10 juvenile females and 10 juvenile males) every alternate hour for 24 h after 1) an increase in cortisol induced by injection with synthetic ACTH (hereafter ACTH), and 2) a 2 min period of handling and restraint. Baseline FCM values, recorded every fourth hour for 24 h before the ACTH and handling treatments, served as controls. FCM values increased significantly following ACTH injection (P = 0.0001) and handling (P