In a 2019 study published in PLoS ONE, Rowena Packer and colleagues examined hair cortisol concentration (HCC) in 135 Border Collies to investigate how chronic stress is shaped by both internal and external factors. The research included 91 healthy controls and 44 dogs diagnosed with epilepsy, a condition used as a model to explore physiological stress impacts.
Hair samples, taken from the dorsal neck area, were analyzed for cortisol using a commercial assay. Results showed that psychosocial stressors—such as living with three or more other dogs—and certain lifestyles, like competitive flyball participation, were linked to higher HCC. Conversely, anxiety-related behaviors (both stranger-directed and non-social) and an epilepsy diagnosis were linked to lower HCC, with seizure frequency negatively correlated with cortisol levels.
Interestingly, some anti-epileptic medications were associated with either elevated or reduced HCC, underscoring the importance of considering treatment effects when interpreting stress biomarkers. The findings suggest that persistent HPA axis activation from chronic stress may eventually lead to a state of hypocortisolism, where cortisol output diminishes over time.
This research highlights the need to account for stressor recency and recurrence when evaluating hair cortisol data and offers valuable insights for canine welfare, particularly in active working or multi-dog households.
Source: Packer, R., Davies, A. M., Volk, H., Puckett, H. L., Hobbs, S. L., & Fowkes, R. (2019). What can we learn from the hair of the dog? Complex effects of endogenous and exogenous stressors on canine hair cortisol. PLoS ONE, 14, e0216000.
