
This is not uncommon, often called " Winter or Snow nose".
I have a dog that hasw slight fading just now and am giving Elderberry and nettle liquid herb, from Dorwest herbs.
Lucy on the board uses another one I will see if I can see her post.
Edited to add
http://www.animal-health.co.uk product is called Pigment plus. Lucy will let you know herself but I am sure she said it has been helping a lot.
It should darking again shortly.. it that is what is causing it.
Pam