I have always had good luck with plain water therapy. Spray it with a hose 2 x day, completely flushing it. You want it to heal from the inside out, and from the edges in. While spraying it, I have used a washcloth with antibacterial soap. With my horses, I scrub the scab off daily, until it starts to bleed. This ensures new tissue growth and minimizes the proud flesh, which horses are so prone to. Then I apply either antibacterial ointment or spray. Repeat daily, or preferably 2 x day. I prefer to leave it open. It will take time, but a slow heal will minimize the scar and keep it from closing up and then festering under the scab.