The Genetics Behind Lacy Coat Colors

Blue Lacy puppy says hi to a red Lacy A Note on "Lacy Dog" vs. "Blue Lacy"
The correct name for the breed is a Lacy Dog. All of the old historical documents we have, including articles written in the 1940s and 50s, call them Lacy Dogs or Lacys. In letters and interviews, Lacy descendants refer to them as Lacy Dogs, Lacy Hog Dogs or Lacys, never Blue Lacys. All of the ranchers in the Hill Country that have been breeding for decades call the breed Lacys or Lacy Dogs. They may say, "I have a Blue Lacy," but they will also say, "And I have a Red Lacy." They never call their red dogs Blue Lacys. The breed name, encompassing all three acceptable colors, is simply Lacy or Lacy Dog.

The best example of a similar naming convention is the Labrador Retriever. People will call a black colored Labrador a Black Lab, but they call a yellow dog a Yellow Lab, even if it came out of two Black Labs. There is no difference between Labs and Lacys when it comes to naming conventions. As you will see in the article below, there is no such thing a blue color gene. All Lacys carry a dilute gene which causes all three color varieties, including Blue Lacys.

According to the documentation, the term Blue Lacy was never used until the 1990s. Though he orginally called them Lacy Cow Dogs in the 1970s, H.C. Wilkes began referring to his dogs as Blue Lacys in the 90s. It is unclear why the term Blue Lacy caught on for a breed that also includes red and tricolor varieties, but it can be misleading and disproportionately emphasizes their appearance. Despite the marketing value in the Blue Lacy name, the NLDA will continue to follow the original naming convention and use Lacy Dog.

Coat Color Genetics
First things first. Genes always come in pairs, and dogs get one gene from mom and another from dad. Likewise, mom and dad each get one from grandma and grandpa. It is possible for recessive genes to be passed down for several generations that never express themselves. So, for the most part, there is no way to guarantee color results. Also, keep in mind that diversity in color genes is healthy, especially for dilute dogs. Don't breed to get a certain color, put the health and performance of the dogs first.

Coat color is all about melanin. Eumelanin is black/brown and pheomelanin is red. White represents the lack of melanin. In this article, we will only discuss melanin, not white. It appears most Lacys have a unique spotting modifier. To prevent improper white markings on the head and above the topline, carefully research your Lacy's pedigree. Litters expressing excessive white may come from properly marked parents, but it is extremely likely their grandparents, uncles or aunts had disqualifying markings.

Photographic comparison of possible Lacy coat colors. Note the nose leather, decided at the B locus, which gives a clue to a Lacy's color genes. Blues and gray are traditionally registered as blue since the coat colors can be almost identical, but genetically there is a difference.

Gray Lacy and blue tri Lacy A Locus
A, the Agouti locus, decides whether a Lacy is solid or tri. Lacys can carry A, solid eumelanin, and at, eumelanin pointed with pheomelanin. AA produces a solid colored dogs. Because A is dominant, Aat also appears solid. You must have two tri alleles, atat, to get a tri. Note that pheomelanin tips on a primarily eumelanin dog, which would appear as a red dog with a blue mouth or obvious blue shading, comes from a separate modifier and is not a standard color.

AA Solid (blue, gray, red, yellow, cream)
Aat Solid carrying tri
atat Tri

Gray tri and blue Lacy puppies B Locus
Next up is B, the Black locus. This is where the fate of eumelanin is decided. The primary method of differentiation is the nose leather. Most Lacys carry at least one B allele and are black. But it appears that the chocolate base, bb, does exist in Lacys, as is noted by the possibility of liver/tan/brown noses. Yes, reds do carry B or b genes, but they are modified later on. A red or yellow Lacy with a brown nose is bb.

BB Black (blue, blue tri, red, yellow, cream)
Bb Black carrying brown (blue, blue tri, red, yellow, cream)
bb Brown (gray, gray tri, red, yellow, cream)

D Locus
This is the gene you've all been waiting for... dilution! The D locus is what takes black and chocolate dogs and turns them into blues and grays. Though it wasn't long ago that blacks were still in the gene pool, selective breeding for dilution has solidified the recessive trait, so now all dogs carry dd at the D locus. Though it has a slight impact on pheomelanin, dd primarily affects eumelanin. It's important to note that because both black and chocolate are eumelanin, they dilute to very similar shades. The main way to tell the difference is the nose colors.

dd Dilution (blue, blue tri, gray, gray tri, red, yellow, cream)

E Locus
So how do we get red, yellow and cream? By suppressing of eumelanin so that only pheomelanin is expressed. Again, E is dominant, meaning the dog only needs one E allele to produce eumelanin. If a dog is ee, they should only express pheomelanin.

EE Eumelanin expressed (blue, blue tri, gray, gray tri)
Ee Eumelanin expressed, suppression carried (blue, blue tri, gray, gray tri)
ee Eumelanin suppressed (red, yellow, cream)

Red and cream Lacys C Locus
The C locus effects the different shades of red and red points on tris. In Lacys, C works on pheomelanin in a similar way to D on eumelanin. C is responsible for the deepest shades of red. The palest shades are ch. C seems to be incompletely dominant, so Cch dogs would be lighter, probably yellow, but not cream. Interestingly, chch dogs are born almost white and darken throughout their lifetime, while CC are born darker and lighten as they get older.

CC Full pheomelanin (darker red)
Cch Moderate pheomelanin (lighter red, yellow)
chch Diluted pheomelanin (cream)

Lacy coat color genetics Putting It All Together
The best way to see how these genes work is to study specific dogs, their parents and their offspring. Let's look at Brutus and Abby, a father and daughter with very different phenotypes. Brutus, the red, is Aat/bb/Cch/dd/ee. Abby, the tricolor, is atat/Bb/Cch/dd/Ee.

Why? Brutus carries at because his father was a tri and he produced a tri daughter. His brown nose means he is bb. He has moderate pheomelanin expression, and he has produced creams, so he is a CCh. We know he is dd due to his dilute offspring. We can see he has no eumelanin and is ee.

Abby has to be atat since she is a tri. Her dark nose means she's Bb because she got a B from her mom that overrides the b from Brutus. Her red points are almost identical to her dad's shade plus we know her aunt was a chch cream, so she is likely Cch. We can visibly see her dd dilution in her blue base. And because she expresses blue but comes from a red, she is Ee.

To learn more about the science of coat color, visit the canine color genetics sites by Susan Bowling and the University of Saskatchewan. Sue Campbell's lesson on Rat Terrier color genetics is also a great resource and is applicable to all breeds.