Melanin is the protein that forms the color found in a dog's coat. There are two distinct types of melanin, (eu)melanin and (pheo)melanin which are produced in the melanocytes found in the skin and hair roots. Eumelanin, which produces either black or brown pigment, is responsible for the color of nose leather as well as hair and skin which explains why a dog’s nose is always black or brown. The production of pheomelanin results in colors from red through yellow, but does not affect skin color.
The color series of genes that are thought to be found in the Havanese are labeled A (Ay = Fawn (cream to red hair with darker tips) or sable (solid black hairs interspersed amongst lighter yellow series of colored hairs) ), B (Black or Chocolate), D (black dilution -born grey), E (affects color), K (affects color), S (white spotting) and T (ticking). There are some that say there is a saddle gene and having many puppies from our Ali I tend to think this is true. All of her puppies either have a black sadle as she does, or a sadle of another color.
The merle gene (M), frequently found in Shelties and Australian Shepherds, possibly the a w allele or wild agouti which results in banded black (eumelanin) or brown with yellow(pheomelanin) hair as is found in some German Shepherds and Huskies and the Harliquin genes, are not thought to be part of the Havanese genetics.
If a dog inherits the dominant gene at the B locus then it will be black. There can be white hairs or spots but the dog is still genetically wired for black. That is represented as BB or Bb. It's nose, eye rims and foot pads will be black. If there is missing pigment in these areas it for another reason.
The lowercase b represents the allele that allows for the creation of the brown or chocolate form of eumelanine. Since this gene is recessive the chocolate dog must inherit a recessive allele (b) from each parent. (bb)
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