I usually treat my chicks as soon as I take them out. I used to use an animal salve that comes in a square red tin, but I can't find the name of it right now. I got it at Orscheln. It seemed to really work on this particular problem, but I would think that other antibiotic wound treatments would work. I cured a couple of chicks by treating them repeatedly and making sure they had sugar water with vitamins while they were getting better. I know people say it can't be done. The first one I treated, I put it in a basket away from the other chicks (and the heat) thinking it would be dead by morning. Instead, it woke me in the night peeping. It wasn't strong yet, but it got stronger and survived. Now I routinely treat all the belly buttons. I haven't hatched for a couple of years, so I am glad I read this thread to be reminded. I will try to post when I find the right stuff.