Which breed is known for having six toes on each foot in some lines?

Norwegian Lundehund is correct because this rare Norwegian breed uniquely has at least six fully formed toes on each foot. The extra toes, along with highly flexible joints and ears that can fold shut, evolved to help the Lundehund climb slick, vertical cliffs while hunting puffins (“lunde” in Norwegian) on remote coastal islands. Unlike other Nordic spitz breeds such as the Icelandic Sheepdog, Norwegian Elkhound, and Swedish Vallhund—which have the typical five toes—the Lundehund’s polydactyl feet provide extra grip and stability on dangerous terrain. Memory tip: “Lunde-hund = Puffin-dog with Extra toes” (E for Extra). This remarkable adaptation also makes the breed a fascinating example of how form follows function in canine evolution and selective breeding.