Richie has a deep crack in his horn, almost like the way a rotten tree branch looks. It's not just surface damage, but goes all the way into the center of the horn - zoom in on the second picture to see the hole. The length of this damaged area is at least three inches. The hole is not oozing anything, nor does it particularly have an odor. I did not go looking into it, because I didn't want to cause more damage or introduce anything into the hole.
Richie does not seem to know anything is wrong. His balance is fine and he is not appearing to have a fever (his ears are not hot). He's eating well and acting like a boy getting ready for rut.
I've contacted both my vet and an experienced goat owner whose daughter is also a vet for advice. My goals are to make sure Richie stays healthy, and if at all possible, keep that horn from breaking. (Goat friends are recommending a course of antibiotics to prevent infection.)