Can cortisol be used to assess acute stress in moose?

Abstract

In this study, the serum concentration of cortisol was measured in 78 hunted moose (Alces alces) shot by rifle. All animals died within 5 minutes after being shot and blood samples were collected. Blood levels of cortisol have been used to assess acute stress and evaluate animal welfare in wild animals, but the animals have been influenced by people during physical or chemical restraint. Little is known about physiology of cortisol in free-ranging moose, and studying these animals without disturbing them are not possible. In the present study, serum cortisol concentrations in shot moose were compared to levels in free-ranging moose immobilized with etorphine-acepromazine-xylazine, medetomidine-ketamine or etorphine in order to evaluate cortisol as a parameter for measuring acute stress. The results showed that the mean serum cortisol concentration in shot moose was 43 nmol/L (2SE = 9). There was no significant difference in cortisol concentration in moose immobilized with etorphine-acepromazine-xylazine and shot moose, probably related to the stress lowering effect of xylazine. The reference values of blood cortisol in moose immobilized with medetomidine-ketamine and etorphine were to 3-4 times higher, probably mainly related to drug influence. The present study indicates that serum cortisol cannot be used as the only variable to assess acute stress in moose and that animals instantly killed by shooting might be used to establish baseline (“normal”) values of cortisol in this species.