Jack Russell Terrier

Last updated April 2016

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 the 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 highly undesirable, it must not be rewarded in the show ring.

General appearance

A strong, active, lithe, working terrier of great character with flexible body of medium length. Smart movement. Keen expression. The coat is predominately white, and may be smooth, broken or rough.

Scars not to be penalised.


Lively, alert and active. A good hunting terrier, sturdily built, that could go easily to ground


Bold, fearless, friendly and confident.

Head and skull

The skull should be flat and of moderate width, gradually decreasing in width to the eyes and tapering to a strong muzzle. The stop is well defined, and the cheek muscles are well developed. The length of muzzle from the stop to the nose should be slightly shorter than from the stop to the occiput. Nose and lips black. Lips tight fitting.


Almond shaped, fairly small and dark, with keen expression. Not prominent. Closely fitting eye rims, with black pigment.


Button or dropped, carried close to the side of the skull, of good texture and great mobility. The top of the ear is level with, or very slightly above the skull. The tip of the ear is in line with the eye.


Jaws strong with a perfect, regular and complete scissor bite, i.e. upper teeth closely overlapping lower teeth and set square to the jaws. Broken or missing teeth due to work are not to be penalised.


Strong and clean, of sufficient length to carry the head proudly, and to protect the feet when working below ground.


Shoulders well laid back with visible forechest, and never heavily loaded with muscle. Upper arm of sufficient length with angulation to ensure elbows are set under the body. Well-boned forelegs as straight as compatible with a short legged dog when viewed from front or side.


The length from the point of shoulder to the buttocks slightly greater than the height from the withers to the ground. Level back, with very slight arch to loin which is short, strong and well muscled. Chest oval, fairly deep rather than wide, with good ground clearance. The distance from the withers to the elbow is equal to the distance from the elbow to the ground. Ribcage oval, well sprung, flattening somewhat on the sides so that the girth behind the elbows can be spanned by two hands - about 40 cm to 43 cm. Moderate tuck up.


Strong and muscular, angulation in balance with the shoulders. Stifles well bent with low set hocks. When standing, pasterns parallel when viewed from behind.


Round to oval, not large, with toes moderately arched. Pads firm.


High set, thick at base, in overall balance with the rest of the dog. When moving the tail should be carried completely erect but may drop at rest.

If docked for work, the tip of the tail on a level with the skull.


Unrestricted, free striding, ground covering gait without exaggeration. Well co-ordinated; straight action front and rear, may converge slightly at a faster pace. Strides should be of good length, never stilted or high stepping. Hindquarters providing plenty of drive.


May be smooth, broken or rough. Must be weatherproof. Not over trimmed.


White must predominate with black and/or tan markings. The tan markings may range from light tan to rich chestnut tan.


25-30 cms (10-12 ins). Substance and weight should be proportionate to height. Neither too coarse nor too refined.


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 and on the dog’s ability to perform its traditional work.


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.