A neighbor rescued a Great Pyrenees from a rooftop during the Flood of 93 - its owner never reported losing him so the neighbor was pretty much stuck with the huge dog and a huge feed bill. He paid me to go over and check on him when he was out of town. He was very good with me never aggressive, but woe to any dog that ventured close.
When I was feeding him I noticed that rain or shine that dog would not go into his dog house, so I decided to check in case there were wasps in it or something.
There were no wasps, it was a nice dog house, well-ventilated, dry, no obvious problems with it at all. Turned out there was a nest of wild cottontail rabbits in the dog house and as far as the dog was concerned they were his charges. He let the mother in to nurse but no cat or dog or any other varmint could get past him, so they were very safe.
What a nice dog! Very sweet story. :-)