The Boston Terrier is a lively, highly intelligent, smooth coated, short-headed, compactly built, short-tailed, well balanced dog, brindle, seal or black in color and evenly marked with white. The head is in proportion to the size of the dog and the expression indicates a high degree of intelligence.
The body is rather short and well knit, the limbs strong and neatly turned, the tail is short and no feature is so prominent that the dog appears badly proportioned. The dog conveys an impression of determination, strength and activity, with style of a high order; carriage easy and graceful.
The skull is square, flat on top, free from wrinkles, cheeks flat, brow abrupt and the stop well defined. The ideal Boston Terrier expression is alert and kind, indicating a high degree of intelligence. This is a most important characteristic of the breed. The eyes are wide apart, large and round and dark in color. The eyes are set square in the skull and the outside corners are on a line with the cheeks as viewed from the front. Disqualify - Eyes blue in color or any trace of blue. The ears are small, carried erect, either natural or cropped to conform to the shape of the head and situated as near to the corners of the skull as possible.
Neck, Topline, Body
The length of neck must display an image of balance to the total dog. It is slightly arched, carrying the head gracefully and setting neatly into the shoulders. The back is just short enough to square the body. The topline is level and the rump curves slightly to the set-on of the tail. The chest is deep with good width, ribs well sprung and carried well back to the loins. The body should appear short. The tail is set on low, short, fine and tapering, straight or screw and must not be carried above the horizontal. (Note: The preferred tail does not exceed in length more than one-quarter the distance from set-on to hock.) Disqualify - Docked tail. Body Faults - Gaily carried tail. Serious Body Faults - Roach back, sway back, slab-sided.
The shoulders are sloping and well laid back, which allows for the Boston Terrier's stylish movement. The elbows stand neither in nor out. The forelegs are set moderately wide apart and on a line with the upper tip of the shoulder blades. The forelegs are straight in bone with short, strong pasterns. The dewclaws may be removed. The feet are small, round and compact, turned neither in nor out, with well arched toes and short nails. Faults - Legs lacking in substance; splay feet.
The thighs are strong and well muscled, bent at the stifles and set true. The hocks are short to the feet, turning neither in nor out, with a well defined hock joint. The feet are small and compact with short nails. Fault - Straight in stifle.
The coat is short, smooth, bright and fine in texture.