Spectre, again, I have no doubt about your ability or resolve. I think we tend to look at dogs, junkyard dogs, even trained family defense dogs, not at the hard trained attack dogs. Hopefully none of us will ever run into one of these attack dogs, when master/owner is not there to call off the dog.
Ayoob says the best medicine is a .357 Mag with nuclear ammo.
If a handgun is used, try to shoot into the mouth and up into the brain pan. Shots to the sloping skull may deflect.
The hard trained attack dog will quit only when dead, and can do a lot of damage after taking a fatal shot. George