
The Chow Chow is an iconic breed, recognizable by its dense coat, varied colors, and bear-like appearance. Among these colors, some are the result of a specific gene: the dilution gene, also known as the D gene.
This gene is one of the most poorly managed by some breeders and is the main cause of the most severe skin problems found in the breed. By altering the pigment intensity in the coat, it can have a direct impact on the dog's health.
In this article, we will explore in detail the functioning of the dilution gene, its potentially severe effects on the Chow Chow's health, and the essential precautions every breeder should take before breeding their dogs.
To begin this article, we will cover some basic genetics, as this information is essential for any passionate breeder who wishes to breed responsibly with the goal of improving the breed.
Of course, this will be an overview, as genetics is a complex and vast subject.
First, it is important to know that a dog's coat color is controlled by genes located at specific loci (precise locations on the dog’s DNA). Every dog inherits two copies of each gene, one from its mother and one from its father.
There are two types of pigments that determine coat color:
✔ Eumelanin: Responsible for black, brown, and their dilutions (blue, lilac).
✔ Pheomelanin: Responsible for red, fawn, and cream shades.
These pigments interact with different genes, creating the wide range of colors observed in Chow Chows.
The main loci that influence the Chow Chow's coat color :
✔ Locus B – Base Color➡ Determines whether the dog will be black (B/B), a black carrier (B/b), or brown (b/b).
✔ Locus D – Dilution➡ Responsible for color dilution:
D/D = Normal color (no dilution).
D/d = Carrier of dilution (can pass the dilute allele but is not diluted itself).
d/d = Diluted color (black → blue, chocolate → lilac, fawn → cream).
Examples:
✔ A black dog (B/B or B/b) with d/d becomes blue.
✔ A fawn dog (Ay/Ay, d/d) becomes cream.
✔ Locus E – Extension (Expression of Black/Brown Pigment)➡ Determines whether black (or brown) pigment is visible in the coat.
E/E or E/e = Black pigment is visible.
e/e = No black pigment → The dog would be entirely red, fawn, or cream with no black shading (like a Golden Retriever).
However, in Chow Chows, the e allele does not naturally exist.➡ All Chow Chows genetically tested so far have been E/E.➡ A Chow Chow E/e is theoretically possible but has never been observed in the breed.
The Locus A – Agouti (Influencing Coat Patterns)
The A locus determines pigment distribution in the coat and influences patterns such as fawn, brindle, or agouti.
In Chow Chows, only the Ay (Dominant Fawn) gene is commonly present.
At (Black and Tan) and a (Recessive Black) exist but are extremely rare.
A Chow Chow Ay/Ay will always be fawn unless another gene (like Kᵇ) masks this expression.
The Locus K – Dominant Black (Masks the A Locus)
The K locus controls solid black coloring and can override the A locus. There are three alleles:
Kᵇ (Dominant Black) → Completely masks the A locus, producing a solid black dog (or blue if the dog is d/d).
kʸ (Recessive, allows A locus expression) → The dog will express the color determined by the A locus (e.g., fawn).
Kᵡ (Partially dominant, very rare in Chow Chows) → Allows a mix of black and fawn patterns.
A Chow Chow that is Kᵇ/Kᵇ or Kᵇ/kʸ will be black (or blue if d/d), regardless of its genotype at the A locus.
A Chow Chow that is kʸ/kʸ will express its fawn color.
A Chow Chow may be genetically fawn, but this color remains invisible because the Kᵇ (Dominant Black) gene completely masks the A locus.
What Makes a Chow Chow Cream?
✔ Locus E (E/E or E/e) → Allows black pigment expression and affects cream shading.
✔ Locus A (Ay/Ay or Ay/a) → Means the dog is genetically fawn.
✔ Locus D (d/d) → Dilutes fawn into cream.
✔ Locus B (B/B or B/b) → May influence cream intensity (a b/b dog could be slightly lighter)
A cream Chow Chow is genetically a fawn (Ay/Ay or Ay/a) diluted to cream by d/d.
The Dilution Gene (Locus D) and Its Role
The D gene is located on the D locus and affects the pigments responsible for coat colors:
D (Dominant, no dilution) → Normal color (black, fawn, etc.).
d (Recessive, dilution) → The coat is diluted when the dog inherits two copies of the d allele (d/d).
This gene affects both eumelanin and pheomelanin:
✔ Eumelanin (black and brown pigments) → When diluted, black becomes blue and brown becomes lilac.
✔ Pheomelanin (red and fawn pigments) → When diluted, fawn becomes cream.
Thus, a Chow Chow cream is actually a diluted fawn (d/d), and a Chow Chow blue is a diluted black (d/d).
Les effets du gène de dilution sur la couleur
Base color | If the dog is d/d (diluted) |
BLACK | BLUE |
RED | CREAM |

The dilution gene does not only modify the coat color, it can also affect:
✔ Nose and eye pigmentation: A diluted Chow Chow will often have a lighter nose and amber-colored eyes.
✔ Coat texture: Diluted dogs sometimes have a thinner or sparser coat.
The Risks of Dilution: Alopecia and Skin Problems
Although the dilution gene is not a problem in itself if properly managed genetically, it is associated with certain pathologies, including:
✔ Color Dilution Alopecia (CDA)
Some diluted dogs (blue, lilac, cream) may develop this condition.
Puppies are born with a normal coat, but between 6 months and 2 years, they begin losing hair in certain areas (back, tail, flanks).
The skin becomes sensitive, thin, and prone to infections.
Not all d/d dogs are affected, but the risk is higher in diluted individuals.
✔ Depigmentation and skin sensitivity
Excessive dilution can lead to loss of pigmentation on the nose, paw pads, and eyes.
Diluted dogs may be more sensitive to UV exposure and skin infections.
📌 It is crucial to understand that one should not acquire a puppy from a mating between two parents carrying the diluted D locus (d/d). In this case, the risks increase, significantly impacting the development of skin diseases.
Breeding precautions : which matings should responsible breeders avoid while aiming to improve the breed?
To limit the risk of health issues related to dilution, here are some key recommendations that we consider essential:
✔ Genetic Testing for Breeding Dogs
Many breeders do not fully understand this subject and should simply test their dogs to determine their genotype (D/D, D/d, or d/d).
This would allow them to avoid breeding mistakes that could negatively impact the puppies’ health.
✔ Favoring Balanced Crosses
The goal is to maintain strong pigmentation and a high-quality coat.
The issue is that many breeders prioritize commercial demand, which favors the purchase of cream or blue Chow Chows.
At Rive de Glovertown, over 70% of prospective adopters, during our video consultations for a potential adoption, request these colors and focus solely on dilution.
We systematically educate adopters on the high risks of mating two dogs carrying the d/d locus, and we strictly refuse to perform such breedings in our kennel!!
✔ Avoiding Matings Between Two Diluted Dogs (d/d x d/d)
This type of breeding significantly increases the risk of CDA (Color Dilution Alopecia) and skin disorders.
At Rive de Glovertown, our color-based breedings always adhere to strict genetic principles to prevent excessive risks.
Example of a Mating We Perform:
✔ A diluted dog (cream or blue – d/d) × A non-dilution carrier dog (D/D) or a carrier of dilution but not diluted (D/d – fawn or black).
✔ In this type of mating, all puppies will be:
✔ Non-dilution carriers (D/D
)✔ Carriers of dilution (D/d)
✔ Diluted (d/d), based on genetic probability
Understanding the genetic transmission of the D locus is essential.
During these matings, probability percentages allow us to predict the possible colors of the puppies. Even though these remain probabilities, this is the best way to understand the transmission of the D locus and to ensure healthy litters.
Here is an explanatory diagram of genetically possible matings and their expected results (without considering other loci).

We therefore understand, from the explanation in this diagram, that two fawn or black Chow Chows (D/D) bred together will never produce cream or blue puppies.
Similarly, a fawn or black Chow Chow (D/D) bred with a fawn or black Chow Chow (D/d) will also never produce diluted colors (cream or blue).
- How to obtain cream or blue?
➡ To produce cream or blue puppies, both parents must carry the dilution gene (D locus). This means:
✔ Two D/d dogs (carriers of dilution)
✔ One D/d dog with one d/d dog (diluted)
However, it is crucial to avoid breeding two diluted dogs (d/d x d/d), a practice that is unfortunately very common for purely commercial reasons.
Breeding should not be based solely on market demand, but above all on solid knowledge, the well-being of the dogs, and a true passion, in order to preserve and improve this magnificent breed that is being lost!
I could expand this article to discuss other transmission loci (A, E, K, B), which are important for understanding genetics in breeding. However, the D locus remains the primary risk factor, as it is the main cause of the severe skin problems that your future puppy may develop.
Today, other "exotic" colors are emerging in the breed, such as:
✔ Brown (b/b)
✔ Merle (which does not naturally exist in Chow Chows and comes from questionable crossbreeding)
✔ Lilac (b/b, d/d), which results from the dilution of brown
Chocolate (b/b) and lilac (b/b, d/d) Chow Chows, which are not recognized by the breed standard, present an increased risk because their pigmentation is weaker. This loss of pigmentation can lead to:
✔ More fragile skin
✔ A higher risk of skin infections
✔ Less protection against external aggressions (UV rays, bacteria, fungi)
On the other hand, black and fawn Chow Chows generally have stronger pigmentation, which gives them more resistant skin and makes them less prone to dermatological issues.
Be vigilant!
Thank you for taking the time to read this article!
I hope you enjoyed it and that it provided you with valuable information on genetics and the unique characteristics of Chow Chows.
Stay tuned, more exciting articles are coming soon!
See you soon, Dylan, your passionate breeder
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