What breed of dog might have a thick-haired, fluffy neck with two hair ridges running down either side? It seems the hair on the top of his neck grows in one direction, while the hair on the underside of the neck grows in the other, and the two types meet on either side of the neck to create these two hair ridges running from under each ear to somewhere around each shoulder.
He looks like some kind of (erect-eared, mostly black but with merle chest and paws) black lab, blue heeler, maybe trace German shepherd mix (because of slender face).
What breed of dog has hair ridges like this on either side of its neck?