Genetics
Yorkshire Terrier Color Genetics: From Black & Gold to Parti
Every Yorkie is born black and gold — but which genes they carry determines whether they stay traditional, become parti-colored, or even qualify as Biewer Terriers.
May 8, 2024 · 7 min read
Why Are All Yorkie Puppies Born Black and Gold?
Yorkshire Terriers carry a genetic pattern called 'sable and tan' at the agouti (A) locus, combined with a graying gene that progressively lightens their black coat to steel blue over 12–18 months. Newborn Yorkies appear black because the melanin in their coat is still fully expressed at birth. As they mature, the graying gene progressively lightens the black areas to a lustrous steel blue, while gold areas (typically face, legs, and chest) remain tan to gold. This is a breed-defining trait — and a predictable one.
The Graying Gene: What Creates the Classic Blue and Tan
The progressive graying gene (G locus) is dominant in Yorkshire Terriers and causes the breed's signature coat change. Almost all traditional Yorkies carry at least one G allele, producing the steel blue and gold adult coat. Dogs that carry two G alleles (GG) may gray faster and more completely. Dogs that don't carry G (gg) may stay darker or show a more diluted, brownish-black — sometimes called 'chocolate' or 'liver' coloring in Yorkies, which is actually a separate gene effect.
What Is a Parti Yorkie?
Parti Yorkshire Terriers carry a recessive piebald (parti) gene (S locus) that creates white spotting in addition to the traditional blue/gold pattern. A parti Yorkie typically shows patches of blue, gold, and white — a tricolor appearance that's distinct from the traditional Yorkie but just as valid as an AKC-recognized color pattern. The parti gene was historically suppressed in Yorkie breeding but is now fully accepted by the AKC. Both parents must carry at least one copy of the recessive parti gene for parti puppies to appear — and both parents must carry two copies (be partis themselves or carriers) for every puppy to be parti.
How the Biewer Terrier Differs Genetically
The Biewer Terrier descends from parti Yorkshire Terriers but carries a distinct genetic identity confirmed by UC Davis in 2007 — a landmark study showing that Biewer Terriers have a uniquely different genetic fingerprint than Yorkies, despite their common ancestry. The key difference: Biewers reliably produce their signature blue/black, gold, and white tricolor pattern with a white belly and legs, while parti Yorkies can vary more in color distribution. Biewer Terriers received full AKC recognition in 2021 as a distinct breed.
Gold vs Tan: The Subtle Difference
Traditional Yorkies carry 'tan' points — which appear gold in adults but are genetically the same phaeomelanin pigment as apricot in Poodles. The intensity of the gold coloring can vary: some Yorkies are pale gold, others are a deep, rich gold-red. This variation is influenced by polygenic modifiers (similar to the Rufus modifier in Poodles) rather than a single gene.