D Locus
Lesson #6 will be based on the D Locus. The D Locus attained it's name from the word Dilute.
Blue and White Boston Terriers, also known as grey or silver and white, are one of the most favored amongst the rainbow of
Boston Terrier colors available.  Blue Bostons are the result of the dilution of the black coat coloration. This diluting of the
eumelanin (black) hair and pigmentation causes a black and white Boston to become diluted.  With research it has been found
that there is more than one mutation of the dilution gene, however, they have yet to map how many. We do know that this
dilution occurs on Chromosome 25 in canines.

Puppies that are blue in coloration are usually born a light to medium blue and darken with age.  Also, blue puppies tend to have
iris color that is grey (sometimes even appearing light blue) but usually darkens to a hazel-brown into adulthood.  Most adult
blues will be found in the hue of a medium to dark steel blue, with dilute pigmentation of nose/paw pads/eye rims to match the
coat.  The blues that seem to stay the lightest are the blue Boston Terriers with the heaviest brindling, as the lighter color of the
brindle enhances the dilution of the coat.

Nose Color:  Blue
Eye Color: Varying shades of hazel and brown
Blue and White
Genetically Known As: d/d
***These Boston Terriers are NOT Seal and White***
Lilac and White Boston Terriers are a beautiful hue of diluted brown and are sometimes referenced as such in place of the word lilac.
Lilacs have also been termed with slang verbiage "champagne and white" though it is a term that is beginning to fade. Because lilac
is a combination of dilute and brown it is understood that there must be a pair of each to produce this coloration. This means that
there must be a double copy of recessive dilute (d/d) and a double copy of brown (b/b) within the genetic color code to result.  If one
set of copies is not present, no lilac can result.

When born, lilac Boston Terrier coats are typically a distinct purple/blue in hue sometimes resembling a very dusty red. Once their
pigment fills in the lilac color of purple hue can be seen on their nose as well. In some lighter lilac coat colors the pigmentation has
been seen as a pale lilac coloration that appears a reddish hue though almost always there is a purple undertone. Lilac coats are
distinctly different from the silver color of a newborn blue Boston's coat as when side by side the two can easily be discerned.  As
with all colors of Boston Terriers, lilacs do tend to darken with age.  With more dilute brown Boston Terriers being produced we are
seeing more variety in hue than ever before.

One very important note to make when looking at lilac Boston Terriers is that when their eyes first open the iris is a bright blue color.
This color blue usually lasts until they are several weeks old, possibly months depending on the puppy, then the iris color changes to
a crisp green.  Most all of the time into adulthood the iris color has changed from the green hue to a light yellow color that is very
beautiful. But just like with any hue of Boston coat there are lilac/champagne Bostons that have "crystal blue" or permanent blue
eyes into adulthood that never change. It is much harder at times to distinguish these crystal blue eyes from the baby blue that fade
to green with some young lilac/champagne puppies.

Nose Color: Lilac to Pale Lilac
Eye Color: Green to Pale Yellow (Hazel)
Lilac and White
Genetically Known As: b/b d/d
***These Boston Terriers are NOT Seal and White***
- With dilutes of any breed there are always questions about skin and coat health. Dilute Boston Terriers do
naturally have a lower hair count per square inch as opposed to their dominantly colored, black and white counterparts.  There have been
instances of dilute Boston Terriers with demodectic mange and skin/coat allergies. It is important to note that there are Boston Terriers of
all colors, even black/brindle or seal, that have the same issues. Color Dilution Alopecia, or CDA, is theorized for all breeds but at current
no tests exists to confirm a diagnosis of CDA.  Supplementing with an immune system booster like NuVet can help avoid skin/coat issues
in all coat colors of Boston Terriers.

- It was once believed that when breeding a pair of blue Boston Terriers that 100% of puppies produced should also be of the blue
coloration. However new findings have proven that there is more than one mutation of the dilute gene.  These mutations allow for the
possibility that two phenotypically (looking at them with the naked eye) blue/white Boston Terriers are genetically different and when bred
together have the possibility of producing both blue (dilute) and black (dominant) colored puppies. For this to happen one of both of the
parents would have to carry a dominant copy of black, and instead of being d/d are actually d/D. This may seem impossible but recent DNA
color analysis of phenotypical blue coloration have resulted with a dominant copy. Not enough is known about this mutation and why it
happens, but it does exist. It is by far a great genetic anomaly and does not occur often.

-There have been cases that two black/white Boston Terriers have produced a puppy that was dilute (blue) in coloration. When tested
neither of the black/white parents carried for dilute. This may seem impossible because we learn that to produce a color each parent has
to carry a color recessive for the color produced. However understanding what you just read in the bullet above about the varying
dilution mutations, it is possible that two black/white Boston Terriers who do not carry for the dilute gene can produce a dilute puppy.
Dilution is the only locus that this mutation can manifest, meaning it is the only locus that two dogs who don't carry for the proper color
recessives to produce the color repetitively can actually produce it one out of a million. It is because of  an understood mutation at
chromosome 28 causing the dilution of pigment and coat color that this occurs. This is how it is believed that the first blue and white
Boston Terrier in history came to be. This dog was known as the Perry dog, said to have been imported from Scotland and incorporated
into the foundational bloodlines in the late 1800s, early 1900s.  It is not likely that the same pair who do not carry dilute and produce one
due to mutation of chromosome 28 will ever again produce a dilute when bred together even if bred together 100 times over.

- Two red/brown Boston Terriers can NOT produce a black or blue Boston Terrier. It is not genetically possible.
***Important Facts To Note About Blue and Lilac Boston Terriers***
I am ready to move onto Lesson #7: Hypothetical C Locus
Please Take Me To Lesson #7        Please Take Me To Color Home
Litter of blue/white and lilac/white Boston Terrier puppies.
Left to right: blue, lilac, blue, lilac, lilac, lilac
Newborn blue/white (left) and
lilac/white (right)
7 week old puppies: blue/white (left) and lilac/white (right)