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COLOUR GENETICS - S locus

The S gene, called the SPOTTING gene, is the one responsible to determine where colour will be deposited as well as how much of the body will be covered with colour or be white. Sometimes, dogs with colour plus white are refrered to as having broken colour coats, the colour is broken with white. The spotting gene may make more sense if you think of white as a mask that covers up the base colour of the dog. There is incredible variation and more than one combination can look similar. Each one blends into the next as we will explore below. Order of dominance is [ S ], [ s i ], [ s p ], [ s e ]. There is more information on the white spotting page.

The name particolour is a general term that encompasses all broken colour dogs regardless of how much or how little colour break there is. More commonly, the term is used for a dog that is more than 50% white with irregular patches of colour.

The coloured portions of the coat may be any colour. For ease of understanding the colour progression, only black/white examples are show here.

dog displays solid colour SOLID: All over solid colour with no white at all or only in minute amounts.
Phenotype - dog displays solid colouring
Genotype - [ SS ]

dog displays white trimTRIM: Small amounts of white possible on chin, chest, feet and tail tip. May be missed especially on light colour dogs.
Phenotype - dog displays white trim
Genotype - [ S s i ]

dog displays irish pied markingsIRISH: Irish Pied markings where the coat is more than 50% coloured with white markings appearing on the face, chest, feet, collar, underbelly and tail tip.
Phenotype - dog displays irish pied markings
Genotype - [ S s p ] or [ s i s i ]

dog displays half colur half whiteHalf and Half: Close to 50% white and 50% colour. Some call this a lightly marked pied or a heavy marked particolour.
Phenotype - dog displays approximately even amounts of colour and white
Genotype - [ S s e ] or [ s i s p ]

dog displays particolourPARTICOLOUR: Classic particolour coat is more than 50% white with irregular splashes of colour.
Phenotype - dog displays particolour markings
Genotype - [ s p s p ] or [ s i s e ]

dog displays extreme particolour / piebaldEXTREME PARTICOLOUR or PIEBALD: Extreme particolour, sometimes called Piebald is a dog that is mostly white with only minimal areas of colour, perhaps only one or both ears, an eye patch, or a spot near the tail.
Phenotype - dog displays extreme white markings
Genotype - [ s w s w ]