The dog was clearly out of its property. Its body was across the property line, so the sonic fence wasn't a deterrent.

We owned a beautiful black Lab for 15 years who thought it was her job as family dog to rush the FENCED property line when people walked too close. A woman pepper sprayed her once because she feared Kana would come over that fence. Kana meant no harm. She was bluffing and she never went over the fence, but she was big, black and scary and the woman had a little kid with her. I could see why it happened. Kana learned not to rear up on the fence because of that incident.

We have since had a Lab husky mix who would and did ignore a sonic fence to intimidate other dogs. We recognized her as a potential threat to herself if not to children and dogs, so we installed a real fence of substantial height to keep her in.

The owners of this dog were negligent with the life of their dog. This was bound to happen sooner or later. Aggressive dogs should be fenced with real fences!