"A native dog's black tongue cannot be exchanged for gold" means that a native dog's tongue is black. The appearance of this oral color is related to the native dog's genetic genes.

It is said that the black tongue native dog has a strong sense of self-protection and hunting ability, and the black mouth can also prevent bacteria Growth and other effects, so it is considered a sign of health. However, there are also opinions that the black tongue of native dogs is due to the high price caused by the hype of traders. The scarcity of this kind of dogs is due to the black tongue phenomenon caused by genetic inheritance. It is not as good as the legend, and there is no difference compared with normal dogs.