This is why we can't have nice things.
Cash has been sporting this bad boy for about two weeks now. It's caused by swelling of the bursae over the elbow, usually caused by some sort of trauma when the horse is lying down. In Cash's case, he lays with his feet tucked under him, and his hoof touches his elbow. He's not lame or anything, although the area is tender.
Since he's retired, the vet and I are opting for the most conservative route - having him wear a shoe boil boot at night, and trying to give him a little more bedding to lay on (never mind he pees in the bedding and lays on the hard ground, right?). The boot will help prevent his hoof from touching his elbow, which should eventually allow the inflammation to go down. We could drain it, do a course of steroids, etc, but frankly it's not bothering him and I don't want to disrupt the delicate balance that is his life. These days the slightest change causes him to worry/pace/not eat, and it's just not worth the risk.
Anybody else ever had a horse with a capped hock or elbow? What did you end up doing?