Vitiligo is a skin condition that causes depigmentation, resulting in white spots on a dog's nose. This can be caused by various factors such as nasal hyperkeratosis or other skin conditions. In most cases, white spots on the nose do not require treatment, unless they are caused by a more serious issue such as a fungal or bacterial infection. Vitiligo can also result in white spotting on a dog's body, and while it may be unattractive, it is generally harmless. Additionally, some dogs may be born with a pigmented nose that later fades to a lighter color, which is known as nasal depigmentation. In such cases, it is important to monitor any changes in size or appearance.