We had one a couple of years ago that was very similar, I got a little larger than that, and I got nervous. We put him out, lanced it on the lowers side, drained it the best we could by squeezing it out the lance, and trying to draw it out with a large needle and syringe, flushed it by injecting the lance with diluted betadine, and gave draxxin. I was completely gone in a week or two. It may rupture on its own, but either way I would consider darting with Draxxin. Why is darting not an option? Not being able to dart really limits your options.