Wow! That is amazing. I have no idea what it could be but think it is strange that it was not bleeding. Maybe Nurse Huney licked away all of the blood. I would take him to the vet just so that no infection starts. The vet may also be able to recognize what the wound came from since they see so many injuries. Kisses for Bon's boo-boo and also to Huney for being such a good sister.