This is called running gold where gold is showing up in the blue colour pattern. Usually the gold hair that shows up in the blue, is a little coarser.
It is a fault and not usually a good idea to use these as breeding stock as that will be passed on in the progeny or further down the line but they are perfectly healthy pets. Often the running gold shows up by about a year of age or shortly after. It can skip generations so knowing sire and dam doesn't tell the whole story.
If the coat is clipped short, the running gold will disappear and you will have the blue saddle until the coat grows out again, then you will see the running gold again.
Some will run so much gold, they look like gold yorkies but you can see the blue saddle usually underneath especially when you clip the coat very short. |