Blind dogs lack both hair and eyes, but their senses of hearing and smell have both increased dramatically, allowing them to survive as skilled nocturnal hunters and scavengers. Not only do they breed true, but feral dogs will often give birth to blind dogs, ensuring their ubiquity. They can be found worldwide.
Hellhounds seem somehow to have gained traits from goats. Most noticeably, hooves and horns, as well as great dexterity on steep terrain and powerful jumps. Their primary prey are wild sheep and mountain goats. They are found in southern Europe and the middle east.
Carrion hounds have shriveled, hairless heads with with manes growing from their necks. Much like the vultures they resemble, they live by scavenging, although they will attack wounded or sick animals. They are found in the Americas, most often in mountainous regions.
Song dogs are similar to coyotes: small, cunning, and furtive. Their complex howling (from which they get their name) keeps them in constant contact with each other even over great distances, but they only meet to mate or hunt. They are found in northern Europe and Russia.