If we had to pick a topic that we receive the most questions about, it would definitely be dog coat color genetics. For many breeds, there is a limited number of coat colors that conform to the breed standard so it is important to have a basic understanding of this complex topic when making breeding decisions. There are also some coat colors and patterns that tend to be favored by future pet parents when looking for their new puppy. As a breeder, you want to make sure that you are making decisions that support your breed and your business. So, we wanted to provide a very basic summary of dog coat color genetics.
As amazing as it might seem, there are only two pigments known as eumelanin and phaeomelanin that make up all possible dog coat colors. The eumelanin pigment can be found in black or brown versions and the phaeomelanin pigment can be found in yellow or red versions. Many of the coat color and pattern mutations we test affect the amount or ratio of these two pigments found in a dog’s coat. Some mutations will select for an all or nothing scenario where only one pigment is produced. For example, our E-Locus test looks for a mutation that when present in two copies, causes only phaeomelanin to be produced leading to an all yellow to red coat. Similarly, we also test for K-Locus that when present in one or two copies causes only eumelanin to be produced leading to an all-black to brown coat in many breeds. There is an additional test we offer for the A-a-Locus mutation that when present in two copies also leads to an all-black coat in a limited number of breeds like German Shepherds. Any dogs that have the mutations for a black coat can produce a brown coat color if they have mutations like B-Locus, B-Locus-AS, and Co-Locus present in two copies.
While some mutations produce a single coat color (black, brown, yellow, and red), there are other mutations that can then act on this base coat color and lead to other colors and patterns. D-Locus and I-Locus are two mutations that can affect the distribution or saturation of color in a dog’s coat. This causes the color to be less distributed throughout the coat which leads to dilution of black, brown, and yellow to colors like blue, charcoal, grey, lilac, or champagne. I-Locus will also dilute a dog’s coat color but only for a dog with a yellow to red base color. There are even mutations like S-Locus that blocks the production of pigment cells all together and lead to white coloring in a range from patches to an all-white coat depending on how many copies of the mutation the dog carries.
Besides producing diluted base colors, there are additional mutations that can affect the distribution of the two pigments in a dog’s coat which can generate a range of coat patterns. Some coat patterns are encoded by A-Locus mutations like black and tan caused by the A-AT-Locus, Wolf Sable caused by the A-AW-Locus, and different versions of sable caused by the A-AY-Locus mutation. Even more complicated patterns can be generated by the Merle or M-Locus mutation that can present differently depending on how many copies of the mutation are present.
Dog coat color genetics can be complicated and definitely more than we can cover in a blog. That’s why we are always available to assist you in navigating the world of dog coat genetics so don’t hesitate to reach out with questions. By working together, we can help promote decision driven breeding that supports your business.