Non-invasive endocrine monitoring using fecal steroid analysis: opportunities and challenges

During the past two decades, techniques for the non-invasive analysis of fecal steroid metabolites (estrogen, androgen, progestagen and glucocorticoid metabolites) have been developed. These techniques have been used for research with mammals, birds, reptiles, and to a lesser extent in fish; species studied included domestic and laboratory animals, as well as captive and free-ranging wildlife. The techniques now are widely accepted, and in many studies in which either blood sampling on a regular basis was difficult or not possible, i.e. in research on wildlife, very stress prone species or animals of small size, it has become a substitute for analyzing steroid hormones in serum/plasma.