Non-invasive measurement of glucocorticoids: advances and problems

Palme reviewed methods for measuring glucocorticoid metabolites non-invasively in faeces, urine, hair and saliva, a cornerstone technique for assessing stress in captive and wild animals without restraint. He explained the physiology of hormone secretion and excretion, the critical need for species- and method-specific validation, the influence of sample collection, storage and gut transit time, and common pitfalls in interpretation. The review is a methodological touchstone for anyone using cortisol metabolites as a welfare indicator, including the many felid studies that rely on faecal glucocorticoid monitoring. It emphasises that without proper validation, hormone data can mislead, and it underpins rigorous physiological welfare assessment in cats and other species.