|Boston terriers come in three acceptable colors: black, brindle, and seal, all with white.|
|This dog would have too little white|
- Too little white
- Lacking the required white chest, muzzle and blaze between its eyes
- Too much white
- Excessive facial white or "splash white"
- Any base color other than black, brindle, or seal
- Liver, blue, lilac, fawn, gold, or tan point
- Not enough skin pigment
- The nose must be completely black
- Blue eyes
- Even a touch of blue disqualifies
|Too much white and a blue eye|
|A splash rescue|
As for the dogs with off-standard base colors, there are really quite a number of possibilities. Here's the full list of possible colors, what they're called in the breed and the genes that cause them. Wherever I say black, this is basically interchangeable with brindle and seal. All three colors are caused by the K-black locus, with brindle (kbr) being recessive to black (K) or seal (K, bad black, possibly recessive to regular black).
|Masked fawn puppy|
- Recessive to black on the K-black locus, allows the Agouti locus to show through: Ay- kk results in sable/fawn
- Dog may or may not have a black mask and may be liver, blue, or lilac instead of black
- Tricolor/tan points
- Also on the Agouti locus: atat kk results in tan point; may be liver, blue, or lilac instead of black
- Non-black pigment that would otherwise be black
- Liver/brown, recessive to black on the Brown locus: bb results in liver pigment
- Blue/gray, recessive to black on the Dilution locus: dd results in blue pigment
- Lilac/champagne, combination of the blue and liver genes: bb dd results in lilac
- Caused by recessive red on the Extension locus: ee results in recessive red/clear red
- This gene hides all black body pigment, so any of the above, including blue/liver/fawn, but skin and eyes can still be effected by the liver and blue genes
|Liver pigment and too much white|
|Two dogs, three blue eyes|
Apparently, there are some people out there selling merle Bostons. This color has been introduced through mixing with another breed. Since merle has so many negatives, there is absolutely no good reason to out-cross to purposefully introduce merle into a breed.
Images are from Wikimedia Commons or Flickr.com under Creative Commons licenses: one, two, three, five, six, seven, eight, nine, ten. Image four is copyright to Rescue Furdaddy on Flickr.com.