Lots of dogs have "ridges", no matter the breed. Often just referred to as cowlicks it seems. I know lots of Dobes who have them on their necks, and plenty of dogs of varying breeds who have them on their noses (both of my Dachshunds had them on their noses). It is the same sort of ridge a ridgeback would have, in the sense that the hair in the ridge lies the opposite direction of the rest of the coat.