PF-06260414 belongs to the selective androgen receptor modulators (SARMs) class of compounds. SARMs were developed as an androgen replacement therapy with fewer androgenic side effects associated with traditional anabolic steroids. They stimulate muscle growth, increase bone density, and enhance lean body mass. Therefore, they are prohibited in both human and equine sports. To control their abuse in equine sports, it is essential to determine their metabolic fate in the horse's body; targeting the metabolites will allow longer detection windows than targeting the main compound. PF-06260414 metabolites were evaluated in-vitro but no in-vivo data is available. In this study, PF-06260414 was administered to 3 horses, followed by urine collection for up to 192 hours. A total of 7 metabolites were detected by liquid chromatography–high resolution tandem mass spectrometry (LC-HRMS/MS).