Animals have had it rough. Humans have only recently begun to find proof that animals are thinking, feeling beings. If that seems stupid, it is because it is. Science moves at a glacial pace when it comes to overturning preconceptions laid by men in the 19th century.
Before scientific prejudice, there was superstitious prejudice. Certain animals were associated with the mystical forces of the world. Black cats are thought to be unlucky. In Vietnam, people believe that eating a dog can not only cure a cold, but it brings good luck too.
European myths hold fast to the idea that seeing a black dog at night is bad. The appearance of a black dog is a harbinger of death. Just like seeing a black cat brings bad luck.
British and Norse mythology tells of another kind of black dog. The Church Grim, Kirkegrim (Danish), Kyrkogrim (Swedish), is a spiritual creature that prowls the churchyard (graveyard) in search of intruders to savage.
Not Just a Dog
The Church Grim isn't really a dog, it only takes the form of one. They are seen as a large black dog with intense eyes and a hunger for wrongdoers. Other forms most typically reported are lambs, horses, and pigs. Whichever animal you have in high supply, really.
Among the powers of the Church Grim is the ability to sense the intentions of anyone entering the churchyard. Thieves, vandals, and practitioners of evil magic are all on the menu. Not even the devil can trespass on a churchyard where the Church Grim dwells.
The Church Grim haunts the bell tower of the church. During funerals, the priest can sometimes see the Grim watching from the bell tower. They can tell whether the soul of the deceased is bound for heaven or hell, depending on the Grim's demeanor.
Bells ringing at midnight are also attributed to the Church Grim in Yorkshire folk belief. Should you hear the bells tolling at midnight, know that someone is bound for death.
No Great Farm in the Sky for You
Folklorists in the 19th century believed that the traditional method to create a Church Grim was to bury an animal alive under the foundation of the church. This animal's ghost would rise as a guardian.
The idea came from the belief that the first person to be buried in a graveyard was condemned to guard it against evil for all eternity. Obviously, no-one wanted to take on that contract. Peasants worked hard enough already. So they made sure it wouldn't happen to a person, by burying a dog (or other farm animal) near the northern border of the graveyard. Thus, the animal would be forced into the contract to guard the graves.
Church Grims also serve as Psychopomps. Much like Charon in Greek mythology, the Church Grim serves as a guide from this world to the next. They lead you from the graveyard, and into the light that they can themselves never reach.