I've operated on bumble foot a few times and I always end up soaking in warm salt water and massaging and squeezing and cutting and prodding for at least an hour sometimes before I find the plug and get all the gunk out. I then fill the hole with Neosporin and wrap the foot with thin strips of vetwrap and put the chicken in a kennel to recover. After a week I take off the vetwrap - the foot has always been healed and the chicken is free to rejoin the flock. I don't give antibiotics and I have not had a chicken get a recurring case or end up limping. Every one has been good as new after surgery. Maybe it's all that hour of soaking in warm salt water - very warm and very salty. Once I had to cut through the top of the toes where the marble size swelling was to get the plug.