Is Hair Cortisol Useful for Animal Welfare Assessment? Review of Studies in Captive Chimpanzees
The objective assessment of animal welfare is important for building consensus among people concerned with animals and for advancing our understanding of animals in our care. The analysis of physiological stress response using glucocorticoids is one of the major approaches for animal welfare assessment. Recently, cortisol accumulated in hair or other keratinous materials of animals has been considered as an indicator of the long-term activation of the hypothalamus-pituitary-adrenal (HPA) axis. Particularly, there is evidence that hair cortisol (HC) can be used as a measure of the long-term activation of the HPA axis in various mammals. This review discusses the utility and limitations of HC analysis for welfare assessment, mainly based on findings from captive chimpanzees living in a sanctuary in Japan. First, the methodological and physiological perspectives of how to to obtain reliable results from HC analysis will be discussed; and second, the potential of using HC analysis for welfare assessment will be reviewed. A series of studies on captive chimpanzees show that HC is useful for monitoring the effects of social management on the long-term stress levels in captive chimpanzees. Although further studies are needed to clarify the extent to which HC monitoring can help us understand and improve animal welfare, application of HC analysis might be useful in investigating similar issues in marine mammals.
chimpanzee, Pan troglodytes, hair cortisol, animal welfare, welfare assessment, social management