My grey ran in the backyard this morning with some other dogs, playing chase up and down the fenced-in yard edge. Two dogs on the other side of the fence, one on his side (my other pup, not a grey), running along a mostly dirt track. When he got back inside, I noticed he was bleeding. He seems to have worn off or torn off a bit of the surface of his paw pad (about the size of a dime or nickel: see image attached). Does anyone have suggestions of 1) how to protect this while healing, and 2) any thoughts on how to protect him in the future? I don't want to keep him from running; he loves it. But I also want to keep the poor guy safe.