Technically called "hypopigmentation" (or snow nose, winter nose) it results from loss of sunlight, and causes the nose to fade to brown in winter; normal colour returns as summer approaches. Snow nose occurs mainly in light-coated breeds; the colour change can become permanent in older dogs. Snow nose can impact a dog at any time of year, although during the darker winter months are most common.
Akira (Toy) on the left, Vicky (Toy) to the right. )
Vicky gets snow nose every winter , not all do,
Akira does not.
