Why is the dog's upper lip suddenly pink? It may be because the dog is frightened or excited, this reaction is normal, or it may be because the dog's lips and skin is damaged or inflammation, so it is recommended to take the dog to the veterinarian.

The dog's upper lip suddenly became pink:

1. The dog's upper lip suddenly became pink. It may be that the dog accidentally damaged his mouth during exercise, resulting in skin damage.

2. The dog's lips should be black. If there is a simple discoloration and no obvious lesions of hair loss or redness around the mouth, it may be due to changes in the body's pigment.

3. If hair loss or redness occurs, it may be a skin disease, which will directly lead to discoloration and hair loss in the dog's skin.

4. It is recommended to take the dog to a pet hospital for corresponding examinations, such as routine blood, inflammatory proteins, and skin examinations to confirm whether there is inflammatory infection and trauma on the skin surface.