Save a Horse, Dive a Cowboy

Shep's just your average all-American cowboy. He runs his own ranch and rides the occasional saddle bronc. Nothing special there. Unless you look too closely at his boyfriend.
Descended from a long line of Native American mustang shifters, Charlie "Hoss" Running Horse is anything but average.
When Coyote takes a shine to Shep, he decides that Hoss has got to go. With the theft of the medicine horseshoe that allows Hoss to shift from mustang to human, Coyote sets his evil plan to have his way with Shep in motion.
Will Shep be able to save Hoss before it's too late? Or will Coyote's plan come to fruition?