Black pigment (left) and brown pigment (right) in Australian Labradoodles. Photos courtesy of GALA member Cream Puff Labradoodles, New Jersey.

A simple look at the genetics behind those black and brown noses

Genetics can sound intimidating. Chromosomes, genes, alleles, loci may quickly start to feel like you need a biology degree just to understand why one Australian Labradoodle has a black nose and another has a brown one.

Fortunately, the basics of how dogs inherit black or brown pigment are much simpler than they sound. Let’s walk through a simple explanation of how dogs inherit black and brown pigment.

Think of DNA as a Giant Instruction Manual

Imagine your dog’s DNA as an enormous encyclopedia of instructions for building and running the body—from coat and pigment to countless processes we never see.

Dogs have 78 chromosomes, arranged in 39 pairs. A puppy receives one chromosome in each pair from Mom and the other from Dad.

Those chromosomes contain thousands of genes.

A gene is essentially a particular set of instructions. And because chromosomes come in pairs, a dog generally inherits two copies, or alleles, of each gene: one from each parent.

Both Mom and Dad contribute equally to each puppy’s genetics.

Dominant and Recessive: What Does That Mean?

Some alleles are dominant, meaning only one copy is needed for that characteristic to be expressed. Others are recessive, meaning a dog needs to inherit a recessive copy from both parents for the characteristic to appear.

An easy way to think about it is:

B = black pigment: Dominant
b = brown pigment: Recessive

A puppy can inherit one of three combinations:

The interesting dog is Bb.

That dog looks black-pigmented because B is dominant, but tucked away in its DNA is a recessive b inherited from one parent. This Bb dog can pass either B or b to its puppies.

So, a black-nosed Australian Labradoodle can carry brown pigment, but one would never know by just looking at the dog.

How Dogs Inherit Black and Brown Pigment

Suppose you breed two black-pigmented dogs.

You might assume all their puppies will have black pigment.

Not always true.

If both parents are Bb, each can pass its hidden brown allele to a puppy. If a puppy receives b from Mom and b from Dad, it is bb and will have brown pigment.

For a simple Bb × Bb pairing, the expected probabilities for each puppy are:

25% BB — black pigment, does not carry brown
50% Bb — black pigment, carries brown
25% bb — brown pigment

And here’s an important breeder lesson: those percentages are probabilities, not a litter recipe.

If a litter has eight puppies, nature isn’t required to produce two BB, four Bb, and two bb puppies. Each puppy is a new roll of the genetic dice. You might get several brown-pigmented puppies, or none at all.

What Is the “B Locus”?

Let’s look at some scientific terminology without making it too scary.

A locus is simply a location on a chromosome where a particular gene is found.

Breeders commonly call the TYRP1 gene the B locus. TYRP1 variants affect eumelanin, a pigment that normally appears black.

Certain inherited variants can alter that pigment, so it appears brown instead of black.

That’s why the difference isn’t limited to the coat. You can also see it in other areas where pigment is noticeable, including the:

• nose
• eye rims
• lips

When breeders describe an Australian Labradoodle as having black pigment or brown/liver pigment, they’re describing something we can see on the outside that reflects inherited genetics.

The real genetics are a little more complicated than simply one B and one b.

We use B and b here to make inheritance easy to understand. In reality, scientists have identified multiple variants of the TYRP1 gene that can produce brown pigment in dogs. Genetic laboratories may therefore test for several brown-associated variants. The simple B/b model illustrates the inheritance principle without requiring a genetics degree!

Why Does a Breeder Need to Know this?

Not because brown is better than black, or black is better than brown. 

Understanding the B locus gives breeders another piece of information when studying pedigrees and planning a litter. Modern DNA testing can tell us things our eyes cannot. A black-pigmented dog, for example, may carry a brown allele that it could pass to future generations.

Color genetics is interesting, but it should always be kept in perspective. Whether dogs inherit black or brown pigment is low on the list of importance in breeder selection.

A DNA test can help us predict pigment. It cannot tell us which puppy will have the wonderful temperament, health, structure, and genetic diversity we want to preserve in the Australian Labradoodle.

Those considerations come first.

And perhaps that’s the most important genetics lesson of all: the more we understand individual genes, the more we appreciate just how wonderfully complex and fascinating the whole dog is.

At GALA, our mission is to preserve and improve the Australian Labradoodle through responsible breeding, education, collaboration, and transparency. We believe informed families make the best lifelong homes, and we hope our educational library helps you make confident decisions for both you and your canine companions.

Written by Anita Main for GALA Education

Anita is a co-founder of the Global Australian Labradoodle Association (GALA) and has bred Australian Labradoodles for more than 18 years. She is passionate about preserving the breed through responsible breeding, education, and genetic diversity.

Sources & Further Reading

• UC Davis Veterinary Genetics Laboratory (VGL). Brown (B Locus) – Dog Coat Color.
  This is probably your best reader-friendly source. It explains the TYRP1 gene, brown pigmentation, recessive inheritance, and the different variants associated with brown coat color in dogs.
  UC Davis VGL – Brown (B Locus)
• Schmutz, S. M., & Berryere, T. G. (2007). Genes affecting coat color and pattern in domestic dogs: a review. Animal Genetics, 38(6), 539–549.
  An excellent scientific review of canine coat-color genetics, including TYRP1 and the B locus.
  PubMed record for Schmutz & Berryere
• Schmutz, S. M., Berryere, T. G., Goldfinch, A. D., & Dreger, D. L. (2002). TYRP1 and MC1R genotypes and their effects on coat color in dogs. Mammalian Genome, 13, 380–387.
  Particularly relevant because this research directly examines TYRP1 and its relationship to brown versus black pigmentation.
• Kaelin, C. B., & Barsh, G. S. (2013). Genetics of pigmentation in dogs and cats. Annual Review of Animal Biosciences, 1, 125–156.
  A more advanced scientific reference explaining how pigment pathways and genes interact to create canine color.
  PubMed – Genetics of Pigmentation in Dogs and Cats
• National Center for Biotechnology Information (NCBI). TYRP1 – Tyrosinase Related Protein 1.
  Useful as an authoritative reference for the gene itself and its biological function.
  NCBI Gene database

• National Human Genome Research Institute (NHGRI). Dog Genome Project / canine genetics resources. The dog genome has 39 chromosome pairs, compared with 23 pairs in humans.

Related GALA Blog: Black or Brown? Understanding Pigment in the ALD