machete, Bullet the guard dog was back on duty yesterday.

Bullet, a pit bull terrier who works behind the Spinning Wheel Night Club, suffered a fractured skull and needed about 20 stitches to close a gaping wound that ran from below his left eye to behind his right ear.

Police were investigating the Saturday night attack, and had a suspect, but no arrests had been made yesterday, a spokesman said.

"The gap was at least one inch wide and three to four inches long,'' said Dr.

Jan Cieters of Hannover Veterinary Hospital. "The dog came in here walking. I was amazed that the dog could still walk.

"The fracture of the skull was not in the cavity of the brain,'' Dr. Cieterrs said. "Otherwise, the dog would have been dead.'' Dr. Cieters said he had seen many attacks on dogs, but none as severe as the one Saturday night on the three-year-old male pit bull.

"The skull was actually fractured,'' he said. "You must use a lot of force in order to crack the skull of a dog.''