It's going to take quite a while for the pad to heel. He will open it up several times no matter what you try to do.
My suggestion is to get some EMT Gel. Everytime he opens it up, clean it out with some saleen or clean water. Then put the emt gel in the cut. You can wrap it up with gauze and an ACE bandage if you want to.
I am guessing it will take at least a month before he quits opening it up and having it bleed. Keep him to minimum activity for a while. It is not a huge deel if it opens up, it is going to happen.
.....you've got to ask yourself a question: 'Do I feel lucky?' Well, do ya, punk?
Die' en ain't much of a livin' son.