Research overview: validating faecal cortisol metabolite assays in captive felids

Faecal glucocorticoid metabolite monitoring is the workhorse of felid stress research because it avoids the confound of capture and restraint, but it requires species-specific validation to be meaningful. This overview surveys the methodological work behind felid cortisol monitoring: physiological and biological validations such as ACTH challenge tests, accounting for gut transit lag between a stressor and faecal hormone peak, the influence of diet and sample handling, and individual baseline variation. It discusses how studies of clouded leopards, cheetahs, tigers and small cats have used these assays to link husbandry to physiological stress, and the caveats in interpreting hormone changes. The synthesis stresses that careful validation underlies all credible felid endocrine welfare findings.