A dog with a black tongue may not necessarily be the best, because the color of the tongue is not the only criterion for judging a dog's quality or health. The color of a dog's tongue may be affected by breed, genetics, environment and other factors.

For example, some specific breeds of dogs, such as Chows, Shar-Peis and Sitters, are naturally gifted with tongues It is black, which is one of the characteristics of the breed. In this case, a dark tongue is normal and has nothing to do with the quality or health of the dog.