If your little pooch resembles a Holstein cow, he's said to have piebald markings. Several breeds of dogs can display these markings, but genetics vary from breed to breed. The piebald gene is also linked to congenital deafness in some breeds.
Piebald Markings
A dog with piebald markings is mostly white with spots of color. These spots are random and asymmetric. The head is usually marked with spots of dark color or completely colored. Depending on genetics, the spots on the body could be large or small, numerous or only a single dark spot. The dark spots can be any color. Piebald is sometimes referred to as parti-colored or random white.
Genetics
The gene responsible for piebald marking in dogs is the MITF gene. This gene is associated with congenital deafness in some breeds including bull terriers, Samoyeds, bulldogs and beagles. Piebald genetics vary from breed to breed. In some breeds it acts as a recessive trait, meaning a dog needs two copies of the gene to display the trait. In other breeds, two copies mean an all-white dog. Some breeds, like collies and Great Danes, need only one copy of the MITF gene to have white spotting.