ths an American Stock Dog mate, some are mixed breeds, some are registered, this one looks like an English Collie (from dogs taken over by English settlers in the 19thC ) but it could also be an American Farm Collie, which looks pretty much the same, like a border but bigger and will work all livestock, not just sheep. They've some crackin herding dogs over there, makes you wonder what kind of lucher they'd produce put to a gh. The Hairy Mouth Heeler would be my choice, multi purpose hunting\herding dog, nearly always working dogs, rarely pets, hard as nails, trainable, rough coat....perfect.