An active, intelligent, muscular, heavy-boned dog with a smooth coat and compact, medium or small structure. Hallmarks are the square head, bat ears and roach back; expression is alert, curious and interested. Features must be balanced, without exaggeration from excess or lack of quality. Allowance is made for females not showing breed characteristics to the same marked degree as males. Height at the withers must relate well to body length from withers to tail onset. The standard sets no numerical height requirement.

Weight must not exceed 28 pounds. Over 28 pounds is a disqualification.

Head large and square; skull flat between the ears, with a slightly rounded forehead. Eyes round, moderately sized, wide apart and low in the skull, as far from the ears as possible, neither sunken nor bulging. Dark brown to nearly black is desired; lighter brown is acceptable but undesirable. No haw or white of the eye should show when looking forward. Blue or green eyes, including any trace of either color, disqualify. Bat ears are broad at the base, elongated with rounded tops, set high but not too close together, erect and facing forward, with fine, soft leather. Any ear other than a bat ear disqualifies.

Muzzle broad, deep and well laid back, with developed cheek muscles, a defined stop and a hollow groove between the eyes. Heavy wrinkles form a soft roll above the extremely short nose; nostrils broad with a defined line between them. Nose black, except that a lighter nose is acceptable but undesirable in creams or fawns without black masks. Any other nonblack nose disqualifies. Flews black, thick and broad, covering the teeth and tongue when the mouth is closed. Underjaw deep, square, broad, undershot and well turned up. Wry mouths and any bite other than undershot are serious faults, not listed breed-standard disqualifications.

Neck thick and well arched, with loose throat skin. Roach back has a slight fall behind the shoulders, rises gradually to a loin higher than the shoulders, and rounds at the croup. Back strong and short, broadest at the shoulders and tapering rearward. Body short and rounded; chest broad, deep and full, well ribbed, with belly tucked up. Tail straight or screwed, but not curly; short, low set, thick at the root and fine at the tip, carried low at rest.

Forelegs short, stout, straight, muscular and wide apart; dewclaws may be removed. Hind legs strong and muscular, longer than the forelegs to elevate the loins above the shoulders, with hocks well let down. Feet moderately sized, compact and firmly set, with compact, well-separated toes, high knuckles and short, stubby nails. Hind feet slightly longer than forefeet.

Coat brilliant, short and smooth. Skin soft and loose, especially over the head and shoulders, forming wrinkles. Any coat other than short and smooth disqualifies; long-haired or “fluffy” coats do not meet this standard.

White, cream, fawn (light through red fawn), or combinations of these. Permitted markings and patterns: brindle, piebald, black masks, black shadings and white markings. Ticking is acceptable but not desired. Brindle ranges from sparse, clearly defined black stripes on fawn to very heavy black striping (“black brindle”); a trace of fawn background is sufficient. In brindle piebald, a trace of brindle in any patch is sufficient.

All colors, markings and patterns not specifically permitted disqualify. The standard’s non-exhaustive examples are solid black, black and tan, black and white, white with black, blue, blue fawn, liver and merle. “Black” here means black without a trace of brindle. Chocolate is commonly used for liver coloration; lilac is also outside the permitted colors. These are not AKC-standard conformation colors, even when a dog is registered.

A four-tracking foot pattern with the front track wider than the rear. Movement has reach and drive and is unrestrained, free and vigorous.

Well behaved, adaptable and comfortable companions, affectionate with an even disposition; generally active, alert and playful, but not unduly boisterous.

Over 28 pounds; blue or green eyes or any trace of either; ears other than bat ears; a nonblack nose except the stated cream/fawn-without-black-mask exception; a coat other than short and smooth; and any color, pattern or marking not specifically permitted. Read the linked official document for the authoritative wording.