Goat going bald!

[Nanno]

having old ones, as well, I'd look at skin fungus (normally the bald patches are circular at first and then spread widely) and would supplement zinc as well. Has he bald circles around his eyes (zinc)? Tips of ears going bald (zinc again)?

I've dealt with skin fungus before (Cuzco got it and gave it to me a few years ago--oh joy!), and this doesn't look anything like that. These patches aren't circular, and this didn't really "start out" as anything--it just began happening all at once over most of his body, but especially around the flanks and behind his shoulder blades (right where a packsaddle would sit). His head, ears, and tail do not yet seem to be affected. No circles around the eyes. 

I do wonder about a sudden hormone change as Hihobaron suggests. You don't usually think of hormones affecting castrated animals, but it's easy to forget that they do still have thyroids and pituitary glands. I read that does will sometimes lose all their hair at once after kidding because of sudden hormone changes. 

This hair loss has started so suddenly that I have a hard time thinking it could be solely due to parasites or a nutritional imbalance. I should *think* those things would progress somewhat more slowly, but I could be wrong.

I'd like to avoid giving a mineral shot because of the selenium content. One of the possibilities I did not mention is selenium toxicity. Vets in this area seldom recommend shots containing selenium because it has been known to kill. Cuzco has lost hair from selenium poisoning in the past, but I dismissed it this time because it always affected him in May/June once the weeds were in (not really an issue now that he can no longer chew weeds), and it also affected the hair on his spine first and worked down from there. So far this hair loss is on either side of the spine and below. Still, even if his selenium levels are ok right now, I try to be very careful of his intake because once they get too much in their system they are prone to becoming toxic very easily for the rest of their lives.