K Locus
We will begin Lesson 2 with the K Locus. The K Locus is where the "traditional" colors of Boston Terriers
are situated. The K Locus attained it's name from the word blac
Black and white is undoubtedly the most classic of the Boston Terrier color rainbow.  When someone
speaks of Boston Terriers, the black and white tuxedo marked American Gentleman comes to mind.  
However, a true black and white may be the hardest color to locate.  The reason for this is because most all
Boston Terriers have some variance of brindle pattern on their body whether it be a few stripes on the
flank or brindle that covers nearly the entire body.

Nose Color: Black
Eye Color: Dark Brown
Black and White
Dominant Black
Genetically Known As:  K
The most important thing to know about brindle is that it is not defined genetically as a color, it is actually a
pattern.  Brindle is the most predominant pattern known in the Boston Terrier rainbow. Brindle was once
believed to be caused by the agouti gene but has since been disproven. This pattern can occur within
almost any color. If the base is dilute the Boston could be a blue brindle or lilac brindle. If the base is brown
the Boston could be a brown brindle or red brindle. Neither fawns nor creams can be brindle as it is
genetically impossible.  Here we see it within the K locus, or as black brindle.

Brindle is known to be recessive to dominant black but not much is understood about this gene on a DNA
level.  Brindle is understood to be eumelanin (black) striping on a phaeomelanin (red/yello) background,
however, depending on the Boston Terrier it may seem to be opposite.  There are many varying shades of
brindle, as the striping can be extreme causing a very dark brindle, or the striping can be very minimal
causing a very light brindle in appearance. In breeds such as Boxers the term "reverse brindle" is used to
describe a Boxer that is almost solid black in coloration possessing a great deal of black striping. Often the
term "reverse brindle" is used by Boston Terrier breeders lacking genetic knowledge to describe brindle
Bostons like those pictured below. This is incorrect as you can see they are primarily limited in eumelanin
striping with a great deal of phaeomelanin shading present.  The below Boston Terriers are simply known
as brindle Bostons, albeit minimal. Many thanks to Animal Genetics, Inc for allowing us to take part in their
research of brindle as it applies to Boston Terriers. With this inclusion we have been able to better
understand brindle as it affects the breed and our program.

Nose Color: Black
Eye Color: Dark Brown
(The above nose and eye color is given as it pertains to traditional black-brindle and white Boston Terriers.)
Black-Brindle and White
Patterning Gene
Genetically Known As:  k
Seal and White is defined by the American Kennel Club Boston Terrier Breed Standard as: "appears black
except it has a red cast when viewed in the sun or bright light".  This color is perhaps the most difficult to
capture color in photograph.  With Boston Terriers, puppies appear to be born with an apparent cast to
their coat that resembles that of a "burnt black" however as they age they seem to outgrow this casting and
most turn to a variance of black/brindle and white.

As seal and white has yet to be successfully mapped by any research team the precise genetic coding is
unknown. It is known that "seal" can be found in dilute black (blue) Boston Terriers and is known as blue
seal. As true black seals are not seen often, this is the same for blue seals. There is research currently
being conducted on whether brown Boston Terriers possess a seal phenotype, but again, not having the
ability to map the black seal genetic recessives, has caused a pause in researching of brown seal.

Nose Color: Black
Eye Color: Dark Brown
Seal and White
The Unknown Gene
Genetically Known As:  ?
I am ready to move onto Lesson #3: B Locus
Please Take Me To Lesson #3        Please Take Me To Color Home
Thank you to Red Fox Boston Terriers of Canada for
allowing the use of their photo (above) to display
seal comparison. Seal brindle at right and in middle.