The rarest dog breed in the world. The norwegian lundehund. Originally used for hunting puffin
The Norwegian Puffin Dog
Lundehund’s forelegs can bend outwards far enough for the dog to lay flat on its chest, with the legs in an approximation of the human arm position. This kind leg flexibility is unheard of, not just in dogs, but in quadrupeds. The only other four-footed mammal that can match it is the reindeer - which also is lives in Norway.
The Norwegian Lundehunds have six toes per foot to climb on vertical cliffs. Able to close their ear canals at will and are able to bend their head 180 degrees backwards over their shoulders. Their fore-shoulder joints are extremely flexible and empower both front legs to be stretched straight out to both sides, for greater ease in swimming and maneuvering in the narrow crevices in Norwegian sea-side cliffs where their avian prey lives.
Norwegian Lundehund. One of the rarest dogs out there... meaning very expensive. They are unique in that they have six toes on each foot, can bend their head back far enough to touch it's back, and it's front legs can can do the "splits" perpendicular to it's head and parallel to the floor. They are very snuggly, but have a rare tummy disorder that causes MANY trips to the vet for checkups.