We rescued a german shephard puppy that needed a right front leg amputation from the knee down. That was three months ago on Aug 17th. He is now 7 months old and the wound is still not healed. About 6 days after surgery the wound burst open, had aslight infection. We cleaned it up got him on atibiotics and the wound was left open to drain. The wound then ulcerated to pretty good size. It has slowly since granulated some but it's still wide open. The outside edges of skin are white and hard. I just don't understand what we can do to speed up healing it's been like this for months. There is no more infection, it is a healthy wound any suggestions please.