‘Bumper’ must have a head harder than that of a Rock Mountain Big Horn Sheep ! !
That dogs head could bring down a mighty oak!
We had a dog that did something like that. Saw Dad down along the roadside, plowed through the woods to get to him. She was sure that tree would move out of her way for him. Dad said he heard the thud, then turned around just in time to see the dog flop over onto her side unconscious.