Does coat color affect cortisol levels in Border collie dogs?

Cortisol is a stress hormone which is released from the adrenals in the Hypothalamic-Pituitary-Adrenal (HPA) axis and plays a major role in animal stress response. Cortisol is used as a stress marker and can be sampled using different methods. A good non-invasive method and a good measure of chronic stress is to measure cortisol through hair. Cortisol is stored in hair for months and therefore reflects chronic stress. The aim of this study was to investigate if cortisol concentration differs depending on coat color. Hair samples from 20 black and white Border collie dogs was analysed and used in this study. Cortisol was extracted with methanol and analysed with ELISA. The results showed no significant difference between black and white coat color within the population while there were individual differences. The results also showed that the sexes do not affect the cortisol concentration. In summary, coat color (black and white) has an effect on cortisol concentration which means that the factor color does need to be taken into account when measuring cortisol through hair