Boston Terrier

Last updated November 2025

A breed standard is the guideline which describes the ideal characteristics, temperament and appearance including the correct colour of a breed and ensures that the breed is fit for function. Absolute soundness is essential. Breeders and judges should at all times be careful to avoid obvious conditions or exaggerations which would be detrimental in any way to the health, welfare or soundness of this breed.

From time to time certain conditions or exaggerations may be considered to have the potential to affect dogs in some breeds adversely, and judges and breeders are requested to refer to Breed Watch information related to this breed for details of any such current issues. If a feature or quality is desirable it should only be present in the right measure. However, if a dog possesses a feature, characteristic or colour described as unacceptable, it must not be rewarded in the show ring.

General appearance

A small, smooth-coated, square-headed, compactly built, short-tailed and wellbalanced dog. Body rather short, well knit, and square in appearance; limbs strong and neatly turned; tail short and no feature so prominent that the dog appears badly proportioned. Dog must convey an impression of strength and activity without heaviness, with a style of a high order and an easy and graceful carriage. A sturdy dog, with bone and muscle in proportion so as to not appear to be either spindly or coarse. Style, body proportion, and basic shape consistent across the weight range.

Important Proportions

Length of body from point of shoulder to point of buttock equal to height at withers. Depth of chest equal to half of height at withers. Length from stop to tip of nose approximately one-third of length of skull.  

Temperament

Lively, intelligent, determined and strong willed.

Head and skull

Skull square in appearance, flat on top, free from wrinkles; cheeks flat; brow abrupt with depth of foreface, stop well defined. Muzzle relatively short, square, wide, and deep; filled under eyes with no tendency to taper to muzzle and in proportion to skull; free from wrinkles; shorter in length than in width and depth. Stop to tip of nose approximately one-third of length of skull; width and depth of muzzle carried out to end; muzzle from stop to end of nose on a line parallel to top of skull; nose black, wide with well-defined line between nostrils. Nostrils open. Jaws broad and square. Clean lip of good depth but never pendulous and completely covering teeth when mouth closed. Size of head to be in proportion to size of dog.

Eyes

 

Set wide apart, relatively large, round, dark in colour. Eyes set square in skull and forward facing, outside corners on a line with cheeks when viewed from
the front. Excessively prominent eyes highly undesirable. Expression alert, kind and intelligent.

 

Ears

Small, thin, triangular in shape with height slightly greater than width, tapering to tip. Mobile but carried erect and upright when alert, outer edge is situated as near corner of the skull as possible.

Mouth

Teeth short and regular, bite even, or sufficiently undershot to square muzzle.

Neck

Of fair length, displaying an image of balance to the whole dog, slightly arched, carrying head gracefully, and neatly set into shoulders.

Forequarters

Shoulders sloping and well laid back, legs straight when viewed from front, set moderately wide apart on line with point of shoulders; well-muscled; pasterns short and strong. Elbows turning neither in nor out.

Body

The length of back just short enough to square the body and the length from point of shoulder to point of buttock should equal height at withers. Level topline with croup that curves slightly to the set on of the tail. The chest is deep, well filled, and with good width; ribs deep and well sprung, carried well back; loin short and muscular; flank slightly cut up.

Hindquarters

Legs set true, well-bent stifle; hocks well let down; turning neither in nor out; thighs strong and well-muscled.

Feet

Round, small, compact, turning neither in nor out; toes well arched.

Tail

Set on low; short, fine, tapering, straight or curled; devoid of fringes or coarse hair, never carried above horizontal.

Gait/movement

Easy and graceful. Sure-footed straight-gaited, forelegs and hindlegs moving straight ahead with perfect rhythm. Each step indicating grace and power.

Coat

Short, smooth, lustrous and fine in texture.

Colour

Brindle: being a mixture of any shade of brown and black with white markings; brindle must show throughout body distinctly; black or seal with white markings acceptable but brindle with white markings preferred. Seal appears black except it has a red cast when viewed in bright light. Ideal markings: white muzzle connected to an even white blaze between the eyes, white collar, breast, part or whole of forelegs, and hindlegs below hocks. A representative specimen should not be penalised for not possessing ideal markings.

Any other colour or combination of colours unacceptable

Size

Weight not exceeding 11.5 kgs (25 lbs) divided by classes as follows: Lightweight: under 6.8 kgs (15 lbs); Middleweight: 6.8 kgs (15 lbs) and under 9.1 kgs (20 lbs); Heavyweight: 9.1 kgs (20 lbs) and under 11.4 kgs (25 lbs).

Faults

Any departure from the foregoing points should be considered a fault and the seriousness with which the fault should be regarded should be in exact proportion to its degree and its effect upon the health and welfare of the dog.

Note

Male animals should have two apparently normal testicles fully descended into the scrotum.

*Note for prospective puppy buyers

Size – The Kennel Club breed standard is a guide and description of the ideal for the breed; the size as described does not imply that a dog will match the measurements given (height or weight). A dog might be larger or smaller than the size measurements stated in the breed standard.