Dogs’ white spots are usually determined by the S series genes. When we say white spots, we mean white areas on the dog’s fur. This is not really a colour and in technical terms it is called epistasis. The gene impairs the ability to produce pigments in cells on certain parts of the skin. White coat colour occurs when melanin is not formed in the skin's melanocytes. In areas where pigments have not been produced, skin, paws and claws will turn pink and the coat become white. However, there may be areas which are pigmented and where a white coat is present.
White spots occur occasionally in the Australian Kelpie, mostly on the chest. The spot can range from a few strands of hair to larger spots. There are a few Kelpies with one or more white paws or a white collar. In the breed standards there is nothing written about how much or how little white may occur on a Kelpie. This leaves room for interpretations. Some do not want more white than a small spot on the chest, while others allow more depending on the rest of the dog’s exterior.
Some Kelpies DNA tested for the gene which gives white spots (the S gene). These dogs have had a white spot either on the chest or one or more paws. The test has shown, however, that they do not carry the S gene. The white on these Kelpies have appeared because of other reasons.
With age some Kelpies grow white areas around the nose, ears and in some cases the paws. This starts with a few strands of hair and grow to be more pronounced in certain areas. Why some Kelpies become more white with age and others do not depends on influences from other genes, not the same genes giving the white spots described above.