There are two main reasons why a dog’s nose is black. The first is to protect the dog’s nose from being burned by the sun, and the second is the intervention of people’s aesthetic tendencies during the breeding process. Dogs with black noses are also relatively common in life, but there are also a small number of dogs that will change color due to acquired environmental changes, diseases, pigmentation, etc. For example, some Labradors with black noses will change color with age. As it grows, the tip of the nose turns pink.
1. Protect the dog’s nose from being burned by the sun
Since the dog’s nose is not protected by hair, the black nose can effectively inhibit ultraviolet rays and prevent the dog’s genes from being exposed to ultraviolet rays. Gene mutations occur. In turn, after exposure to sunlight, these substances will further darken, so that the dog's black nose will become darker and darker without fading.
2. Intervention of people’s aesthetic tendencies in the breeding process
Black-nosed dogs are more popular with people, so people will tend to continue them when breeding new breeds this health characteristic. Although this is only a human aesthetic requirement and has no other meaning, it is also an artificial selection after all, and it will still affect the pedigree of domestic dogs.