I’m not gonna say I’m a gun expert, but I don’t see why you need a loaded shotgun in the back of the car to begin with. Like isn’t only having your gun loaded when you’re ready to use it a pretty common gun safety thing? Even if the safety was on and the dog accidentally turned it off, or the safety was faulty, I feel like there was no reason for it to be loaded and somewhere in the back seat a dog could walk over it or however it happened.