Shar Pei
The blue-black/purple tongue gene appears to be dominant, as most mixed breed dogs that come from a Chow Chow retain that tongue colour. However, the blue-black/purple tongue can also be found on the Shar Pei. This is not to say that every mixed breed dog with spots of purple on the tongue is descended from Chow Chow, as purple spots on the tongue can be found on other purebred dogs.