The Rat Terrier was originally bred for ratting and farm work. A multipurpose companion dog that is capable of hunting rodents and vermin above and below ground, and to course small game. He is a sturdy, compact, small-to-medium sized parti-colored dog giving the appearance of elegance and fitness, denoting speed, power and balance. Honorable scars or a couple of broken or missing canines or incisors teeth are not to be faulted. The following is a description of the ideal Rat Terrier. Variations are penalized to the extent of the deviation.
The head resembles a smooth, blunt wedge from a front or profile view. When seen from the front, the head widens gradually towards the base of the ears in an unbroken line and is well filled up under the eyes. The expression is intelligent, alert and full of interest. The eyes are not large. They are obliquely set wide apart and are oval in shape. Eye color varies with coat color from darkest brown to hazel. Eye rim pigmentation corresponds with nose color and facial markings. Gray eyes are acceptable in blue or blue-fawn dogs only, being a serious fault in other colorations. Any blue in the eye(s) is a disqualification.
The body is compact, strong and flexible with well sprung ribs. The brisket extends to the elbow. When viewed from the front, the ribs appear to be oval. The Rat Terrier, while muscled and fit, has flat muscles that blend into the body. The chest is moderately wide and well filled with a discernible forechest. The underline ascends gradually with the ribs extending well back to a moderate tuck-up. Back - The back is level and firm from the withers to the loin. The short loin has a slight muscular arch blending into the gently rounded croup.
The shoulder blades are well laid back with flat muscles providing enough space between the shoulder blades to allow for free movement. The shoulder blades and the upper arms are nearly equal in length and well set back so that the elbows fall directly under the highest point of the shoulder blade. The depth of the body at the elbow is the same distance as from the elbow to the ground. The forelegs stand straight and parallel with elbows turning neither in nor out. The pasterns are slightly sloping when viewed from the side. The feet are oval in shape. The toes turn neither in nor out, are compact, moderately arched, with thick pads and strong nails. The front dewclaws may be removed.
The hindquarters are muscular but smooth and in balance with the forequarters. They should not be bulging or coarse. Stifles are well-bent with short hocks that are parallel and perpendicular to the ground. The hind feet although slightly smaller are similar to the front feet. Rear dewclaws are removed.
Short, close lying, smooth and shiny coat. Texture varies; a very slight ruff or wave along the back is allowed, but undesirable. Any suggestion of kink or curl is cause for disqualification. Whiskers must not be removed. Absence of coat (total genetic hairlessness) is a disqualification.