Once he has this bone it becomes very dear to him and he does not want to share it with any other dog. So, he takes it to some solitary place. There, he looks at it, admires it and starts gnawing on it. Since it is an old bone it is very hard. With all his enthusiasm and strength he goes on biting until he dislodges a tooth from his gums.
Some blood spills out and oozes onto the bone.
The dog is convinced that the blood has come out of that bone, and he immensely enjoys the taste of it. The dog does not realize the truth. Just as in the case of the baby, he has become deluded by following the imaginations of his own mind.