French Bulldog Color Genetics Explained

With the advances in DNA testing technology, breeders have been able to better predict the color, health, and other attributes that will be found in any litter or potential litter. The most common companies used for genetic testing on French Bulldogs are Animal Genetics, UC Davis, and Vetgen (Our preference is Animal Genetics). There are others to choose from, but at this time not all of them are able to perform the tests you may be interested in. Although health testing is the most important consideration, today we’ll be focusing on color and appearance.

Every potential pup is going to be a 50 percent combination of our stud and dam. They will each pass along one of each chromosome that will determine the complete DNA structure of that pup. Inside the DNA, there are sequences called genes that will establish all of their genetic traits. Every gene contains directions for their body to create proteins, which is how that pup will know whether to develop blue eyes, long hair, or in our example color.

In the case of color, the potential pup will require two copies of any given color gene to produce that color. One copy does not contain the directions required for the pup to develop the corresponding pigment, it will always need two. This does not hold true across all traits, for instance, if a pup carries only one copy of the brindle gene, it will still develop with brindle. When a pup carries multiple pairs of colors, sometimes one color will dominate, which is the case with cream, or they may go on to create an entirely different color such as blue or lilac, depending on the exact pairing.  Let’s have a look at what the exact pairing looks like.

Before we start, a common way you will see a color represented is in a letter pairing, such as “e/E, e/e, or EE” (E-Locus Gene or Cream).  These two letters indicate a particular gene pairing on that pup, a small letter indicates a positive test and the capital letter indicates a negative test. It doesn’t matter which order these pairings are in. Small letters on both sides indicate the pup carries the entire gene and will be showing that color on their coating. One small letter on either side indicates the dog carries the instruction set and it can be passed along to future litters, they are known as carriers.  Carriers will not show the color visibly. Two capital letters indicate that the pup will never be able to create a litter of that color.

** Important note – you may also see “N” or “n” in place of a capital letter to represent a negative finding **

Visual Example:

e/e – Will show cream

e/E or E/e – Carries cream, but will not show it (may also be expressed as e/n).

E/E – Does not show or produce cream (may also be expressed as N/N or n/n).

Here are the common color traits that you can have tested:

The dilute gene or D Locus is known to create a less saturated version of coloring when both pairs are present, without any pairing below it will look like a darker blue. In a combination with other colors, you can end up with the following:

Notice that it requires all lower cases, if any of these are in upper case it would not produce the corresponding color. Let’s take a look at a real-world example where we have two dogs we are looking at mating and you want to know the odds of creating a particular gene pairing. The male is a visible cream dog, which carries a genetic pairing of e/e + D/D. The female is a cream carrier, so she doesn’t appear cream but carries one copy which is expressed as E/e, and carries one copy of dilute expressed as d/D.  In this example, we can expect to produce 50 percent visibly cream, and 50 percent cream carriers. We can also expect the dilute gene to be passed from the female to create carriers half the time, and half the time the gene will be absent. This combination can be easily broken down by placing the genes on the Punnett square which helps predict pairings visually. In the example below, the male genetics are shown horizontally and the female vertically.

These figures can only serve as an estimate of what genes a potential litter will inherit, there is no guarantee on what genes will be passed along from carriers. The only certainty will be that any time visible carrier genes are matched, they will produce a complete litter with that visible gene. For instance, a stud carrying visible cream (e/e) and a dam carrying visible cream (e/e) will produce a pup carrying cream (e/e). The same is true when the gene is completely absent, it will be completely absent from the litter.  When trying to evaluate your odds of multiple color genes being passed by carriers, you can utilize a color calculator to determine the odds in a pairing.

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