Breeds like the Newfoundland and black lab have icons of love and loyalty, but black
dogs also have an infamous form. Folklore and fiction tell of black dogs with glowing eyes that
appear as an omen of death. These dog-shaped demons go by my many names including the
Barghest, The Hound of the Baskervilles, and Black Shuck. The name has changed as the
legend moved from its birthplace of England to the Americas, as has its meaning. In some
accounts, this mythical black dog foreshadows death, while in others, it is more like a beast that
harms those who encounter it.

The good news is, your beloved pup probably isn’t a demon, but that sadly also means
they aren’t immortal. At Carneum, we strive to make every pet’s passing respectful through a
process you can trust. It may be spooky season, but navigating the passing of a pet shouldn’t
have to be frightening.

https://en.wikipedia.org/wiki/Black_dog_(folklore)