There may be many reasons why a dog’s lips may become dark. Here are some possible reasons:
Heredity: Some dog breeds are born with black lips, such as German Shepherds, Labradors, etc. Ladoux etc.
Age: As dogs age, their lip color may become darker, including black.
Exposure to the sun: Prolonged exposure to the sun may cause your dog's lips to darken as melanin is stimulated and increases.
Skin inflammation: Some dogs' skin may become inflamed for some reason, and this inflammation may Causes lips to darken.
Drugs or foods: Certain drugs or foods may cause your dog’s lips to darken.
In general, the darkening of a dog’s lips may be natural, or it may be caused by external environment, age, health and other reasons. If your dog's lip color suddenly changes and is accompanied by other symptoms, it is recommended to consult a veterinarian promptly.