Measuring total cortisol levels in grey wolves, Canis lupus, through a novel, non-invasive technique

The stress response is regulated by the Hypothalamus-Pituitary-Adrenal axis which results in the production of glucocorticoids (GC), a class of steroid hormones, released from the adrenal cortex. The most common techniques used to measure glucocorticoids utilize invasive blood sampling, which can act as a stressor itself and cause an elevation in plasma glucocorticoids. Noninvasive techniques have become increasingly implemented in the last decade and utilize fecal, rather than plasma, glucocorticoids. The technique described here improves on measurements of metabolized glucocorticoids and utilizes a non-radioactive enzyme immunoassay. The cortisol dynamics of the grey wolf (Canis lupus) were studied using this technique. Cortisol dynamics were investigated with respect to wild verse captive cortisol levels, captive male verses captive female cortisol levels, and captive dominant verses captive subordinates cortisol levels. No significant difference was found in cortisol levels between wild and captive wolves (one-way ANOVA, p>0.05). Captive males and females did not have significantly different levels of cortisol (one-way ANOVA, p>0.05), and captive dominants and subordinates did not have significantly different cortisol levels, N=35 (one-way ANOVA, p>0.05). A non-invasive measurement of total GC production will help give a better understanding of overall stress dynamics and allow for more accurate evaluation of stress without added human interaction.