Agree with Don Rae. Any puncture near a joint needs medical attention ASAP. What were the circumstances leading up to the injury? If this attack was not provoked, that roo needs to be put down, and if the neighbor is reluctant to do so, you need to file a police report. This roo is a menace unless your son was in some deliberate way antagonizing him. Also, take photo of the injury today for future evidence.