I didn't read all of the thread, I'm working through it, but SUGAR WILL WORK.
One of the lesson horses got a gash on his hind end, we thought it was just a bite mark, so let it go, not knowing exactly how deep it was. Few days later it smelled like death, so had the vet out and he was able to stick his WHOLE HAND in. The vet came for weeks, and had told us to put sugar on it to keep infection out, IT WORKED and is COMPLETELY HEALED. I can take a picture of the wound tomorrow, if you'd like. I'm looking for one now of the injury after the vet came out..