Less single dogs like Cerberus and more mythological dog races
I'm thinking of stuff like Hellhounds, Black Dogs, Fae dogs (Cù-sìth ect.) and Kobolds (Kazuma Kaneko says they're dogs and who are we to question him!!!)
Ukrainian folklore tells us about a dog type that's said to be able to see spirits. They are born when three generations in a row the first puppy is female, and that dog's first puppy is a yarchuk. Some stories say there should be 9 generations instead.
They're usually described as black, and they have two white spots under their eyes that allow them to identify witches and evil spirts.
Yarchuks are mortal enemies of witches and they're able to give them unhealing wounds with their wolf tooth, while regular dogs will not even bark at a witch.
Lots more info about them, in Ukrainian and Russian but you can autotranslate:
https://www.bestiary.us/yarchuk/ru
And I found a good art of the dog:
https://www.artstation.com/artwork/g8A95P
