White shepherd noses often lighten in the winter due to the colder temperatures. They get darker again in the spring and summer. They often lighten with age too, so as a dog gets older they may get lighter each winter and not get as dark in the summer again. It's not a health problem at all, just cosmetic. The enzyme in the skin that is involved in the production of the skin pigment melanin is temperature sensitive like all enzymes are. Therefore, less melanin is produced when the skin is cold.
Dark shepherds and
many other breeds do this too. Dogs who live in a warmer house or
in a southern climate tend to fade less. There is a genetic factor too.
Dogs with blacker pigment all year round tend to produce puppies with
darker pigment year-round. All of my dogs have black noses in the
summer and a few of them fade to dark liver in the winter. I try to
select only the ones with the best pigment for breeding so that each
generation will be darker than the last.
This site created June 4,