Evaluation of Salivary Progesterone Profiles as an Indicator of Reproductive Status in Equines

Diagnostic assays of reproductive hormones are usually performed by veterinarians on mares to confirm the findings of trans-rectal palpation and/or reproductive ultrasound examination. Of the reproductive hormones, progesterone (P4) is one of the most commonly measured hormones in the field of equine reproduction. Serum P4 concentration in mares is usually evaluated using an extracted radioimmunoassay (RIA), which is generally considered as the gold standard in reference laboratories. However, the use of RIA for serum P4 measurement usually involves a lengthy process to extract the steroids from carrier proteins. Up to 95% of the steroid hormone binds to carrier proteins. [...]