my fave bit of black dog folklore is that in some folklore there is a belief that the first person buried in a cemetery stays there and doesn’t cross over and helps other spirits move on and protects them from evil spirits, now naturally people want to avoid this fate for their loved ones and themselves so they would sometimes bury a dog first and it would return in the shape of a big black dog and protect the newly dead from evil spirits and occasionally the living as well
this kind of spirit is called a church grim
You mean it’s called a good doggie.