A friend has traveled trans-Atlantic a couple of times with her pet Chihuahua in an approved bag. Although it did get out on the second occasion during the night and she and the CC had to search the cabin whilst poor folks were sleeping.
But clearly anything bigger than a cat should go in the hold.
In this case i would also put some blame on the owner. Bulldogs dont have the best respiration at the best of times, and unless it was young was probably too big for a cabin pet bag. She should have had some common sense to refuse to put it in the overhead, or to come on the plane in the first place with that situation.