I see so many posts about this, everyone with poultry should read. It's so much easier to prevent things. All it takes is some knowledge and preparing. True, not all cases can be prevented, but if only half can how many healthier, happier birds and owners would be out there.
I came across your article while preparing to do my own. I recently had a young guinea keet come down with wry neck. I asked a friend whom works at the feed store I use and she told me to try poultry drench. I picked up a bottle at tractor supply and used a dropper to give the keet 2 small doses a day. By the morning of the 3rd day the keet was fully recovered.
My plan going forward is to add a dropper full of drench to all waterers once a month so my guineas and hens can get their required vitamins! I will also be taking advantage of the list of herbs you provided!