The Border Collie breed of dog is the world’s premier sheep herder, prized for its intelligence, instincts and working ability. Medium-sized and athletic, the breed controls stock with stalking movement and an intense gaze known as "eye." The Border Collie also has an uncanny ability to reason, enabling him to work out of sight of its master without commands. The Border Collie breed of dog is the world's premier sheep herding dog. The Border Collie is a well balanced, medium-sized dog of athletic appearance, displaying style and agility balanced with soundness and strength. His hard, muscular body suggests effortlessness and endurance. The Border Collie is extremely intelligent, with its keen, alert expression an important characteristic of the breed. As a true working sheep dog, "honorable scars" and broken teeth incurred in the line of duty are acceptable. The body, from prosternum to point of buttocks, is slightly longer than the height at the withers with the length to height ratio being approximately 10:9. Bone must be strong: medium is correct, but lighter bone is preferred over heavy. Overall balance between height, length, weight and bone is crucial and is more important than any absolute measurement. Dogs must be presented in hard working condition. Excess body weight is not to be mistaken for muscle or substance. Any single feature of size appearing out of proportion should be considered a fault. The expression of the Border Collie breed of dog is intelligent, alert, eager, and full of interest. Eyes are set well apart, of moderate size, oval in shape. The color encompasses the full range of brown eyes, dogs having body colors other than black may have noticeably lighter eye color. Blue eyes (with one, both or part of one or both eyes being blue) in dogs other than merle, are acceptable but not preferred. Eye rims should be fully pigmented, lack thereof considered a fault according to degree. Ears are of medium size, set well apart, one or both carried erect and/or semi-erect (varying from 1/4 to 3/4 of the ear erect). When semi-erect, the tips may fall forward or outward to the side. Ears are sensitive and mobile. Skull is relatively flat and moderate in width. The skull and muzzle are approximately equal in length. In profile the top of the skull is parallel with the top of the muzzle. Stop is moderate, but distinct. The muzzle is strong, tapering slightly to the nose. The underjaw is strong and well developed. Nose color should match the primary body color. Nostrils are well developed. Lack of nose pigmentation is a fault according to degree. Teeth and jaws are strong, meeting in a scissors bite. Complete dentition is required. Missing molars or pre-molars are serious faults as is an undershot or overshot bite. The neck of the Border Collie breed of dog is proportional to the body, strong and muscular, slightly arched and blending smoothly into the shoulders. The back is level from behind the withers to the slightly arched, muscular loins, falling to a gently sloping croup. Body is athletic, with a deep, moderately broad chest reaching no further than the point of the elbow. The rib cage is moderately long with well sprung ribs. Loins moderately deep and short, muscular, slightly arched and with a slight but distinct tuck up. The tail is set on low and is moderately long with the bone reaching at least to the hock. The ideal tail carriage is low when the dog is concentrating on a given task and may have a slight upward swirl at the end like a shepherd's crook. In excitement, it may be raised proudly and waved like a banner, showing a confident personality. A tail curled over the back is a fault. Forelegs should be parallel when viewed from front, pasterns slightly sloping when viewed from side. Because sufficient length of leg is crucial for the type of work the breed is required to do, the distance from the wither to the elbow is slightly less than from the elbow to the ground and legs that are too short in proportion to the rest of the body are a serious fault. The shoulder blades are long, well laid back and well-angulated to the upper arm. Shoulder blades and upper arms are equal in length. There is sufficient width between the tops of the shoulder blades to allow for the characteristic crouch when approaching and moving stock. The elbows are neither in nor out. Feet are compact, oval in shape; pads deep and strong, toes moderately arched and close together with strong nails of moderate length. The hindquarters are broad and muscular, in profile sloping gracefully to the low set tail. The thighs are long, broad, deep and muscular. Stifles are well turned with strong hocks that may be either parallel or very slightly turned in. Dewclaws may be removed in front and should be removed in the back. Back feet, although slightly smaller, are the same as front. The coat of the Border Collie breed of dog comes in two varieties: rough and smooth. Both have close-fitting, dense, weather resistant double coats with the top coat either straight or wavy and coarser in texture than the soft, short and dense undercoat. The rough variety is medium in length. Forelegs, haunches, chest and underside are feathered and the coat on face, ears, feet, fronts of legs is short and smooth. The smooth variety is short over the entire body, is usually coarser in texture than the rough variety and may have slight feathering on forelegs, haunches, chest and ruff. Neither coat type is preferred over the other. Excess hair on the feet, hock and pastern areas may be neatened for the show ring, but the Border Collie should be presented as a natural and true working dog. Whiskers are untrimmed. Dogs that are overly groomed (trimmed and/or sculpted) should be penalized according to the extent. The Border Collie comes in all colors and combinations of colors and markings. Solid color, bi-color, tri-color, merle and sable dogs are to be judged equally, with no one color or pattern preferred. White markings may be clear white or ticked to any degree. Random white patches on the body and head are permissible but should not predominate. Color and markings are always secondary to physical evaluation and gait. The Border Collie breed of dog is exceptionally agile, able to suddenly change speed and direction while maintaining balance and grace. Endurance is its trademark. The Border Collie's most used working gaits are the gallop and a moving crouch (stealth) which convert to a balanced and free trot, with minimum lift of the feet. The head is carried level with or slightly below the withers. When viewed from the side, the trot covers the ground with minimum effort, exhibiting facility of movement rather than a hard driving action. Viewed from the front, action is forward and true without wasted motion. Viewed from the rear, hindquarters drive with thrust and flexibility with hocks turning neither in nor out, moving close together but never touching. The legs, both front and rear, tend to converge toward the center line as speed increases. Any deficiency that detracts from efficient movement is a fault.