. >> i was very angry and confran >> she was a navy corpsman. co cocorpman.>> she was shot ft her injured arm just got progressively worse. >> i had it amputated when it just couldn't be saved. withdrawn and angry, and then someone suggested she try horse therapy, here. >> okay, i will go but i'm only doing it once, they don't understand me, don't know what i've been through. >> only once turned into more a year now. >> it's very moving seeing how healing this can be. >> after the first day i knew this is what i needed and this is where i needed to be at. >> thing that makes the difference. >> this medical school's doctor wants to know why, she has been studying horse therapy for several years and early findings suggest that the reason it works is a common psychological state shared by horses and veterans. it's called hyper vigilance where vets who come home from this feel like they have to stay on guard and amped up all the time. hyper vigilance all the time. >> dr. monroe says that commonality forces veterans like kelley to change their behavi