Of all the characters in the dog, coat color inheritance is among the best understood. It is, however, complex and involves at least ten genes, some of which are multi-allelic (occur in more than two alleles, or forms). There is some disagreement about the multi-allelic genes but, over all, most are clearly defined and undisputed.

• B: This gene has two alleles.
  B - dominant black. This allele allows black to be expressed (wherever expected) and always gives a black nose.
  b - recessive, inhibited-black. This allele results in chocolate brown (wherever expected) and always gives a brown or liver nose.
• DILUTION: This gene has two alleles.
  D - results in normal pigment.
  d - diluted pigment; that is, changes black into blue, or chocolate into fawn.
• MERLE: This gene has two alleles.
  M - merle, having basic color blotched with darker color (black or red).
  m - normal color.

  In breeds where M occurs, the Mm dog is merle in color. MM is a semi-lethal combination. MM dogs will be predominantly white, blind and weak in constitution.  

  Historically the word "merle" was used to describe "marbled (mottled, ticked, flecked)" coat colors.

• ALBINO: This gene has four alleles.
  C - dominant for the production of pigment (melanin). Also called "coloured".
  c^ch - chinchilla or partial albinism.
  c^d - white coat with dark eyes and nose.
  c^a - albino, with no pigment, white coat, pink nose and skin, pink or blue eyes.