The standard for the Boston Terrier states: the tail is set on low, short, fine and tapered, straight or screw, must not be carried above the horizontal. (Note: the preferred tail does not exceed in length more than one quarter of the distance from set-on to hock.)
DISQUALIFY - Docked tails
FAULTS - Gaily carried tail
By the mentioning of the word “TAIL” in the standard, it is obvious there must be something there folks!
By the absence of a tail, it should be faulted with respect of the deviation from the standard.
That said, the absence of the tail is NOT a disqualification, and one should weigh the deviation against the other specimens of the breed.
Also keep in mind, a Boston Terrier is born with little to no tail. By no means, should there be any cosmetic alterations.
The standard notes the preferred tail should be less than 1/4 the length from set-on to hock. This allows for a pretty decent length of tail. No where in the standard does it say that a Boston Terrier should not have a tail.
There are two things to remember:
The tail should never stick out of the silhouette and take away from general appearance.
Health issues. We don’t want the absence of a tail or a tight tail.
The standard allocates 15 points to the neck, topline, body and tail, so keep it in perspective. The thing to remember is that it should be short, fine, and tapered.