The Jack Russell Terrier Standard

As stated by the Jack Russell Terrier Club of America (JRTCA), the largest breed club devoted to this breed, “Jack Russell Terriers are a type, or strain, of working terrier. They are not considered purebred in the sense that they have a broad genetic make-up, a broad standard, and do not breed true to type. This is a result of having been bred strictly for hunting since their beginning in the early 1800’s, and their preservation as a working terrier since. The broad standard, varied genetic background based on years of restricted inbreeding and wide outcrossing, and great variety of size and type are the major characteristics that make this strain of terrier known as a Jack Russell such a unique, versatile working terrier.”  

 Still, there are physical characteristics every Jack Russell should have in common, and these are described in the breed standard. The Jack Russell must be compact and in totally balanced proportions. The shoulders should be clean, the legs straight, and the chest easily spanned by average-sized hands at the widest part of the dog behind the shoulders. The chest must be compressible. This required conformation allows the terrier success below ground, where he must be able to maneuver underground in narrow dark tunnels to get to the very flexible fox.   

In the following section, the words in quotes are taken from the breed standard written by the JRTCA. It begins by saying the Jack Russell “should impress with its fearless and happy disposition.” The Jack Russell Terrier is “a sturdy, tough dog, very much on its toes all the time. . . . The body length must be in proportion to the height, and it should present a compact, balanced image, always being solid and in hard condition.” 

The dog should not be slack of muscle or overweight. Nothing should be exaggerated about the dog’s appearance. A dog with a long back and stubby, crooked little legs is not acceptable. The dog should be a nice-looking, harmonious package, with everything in proportion. 

He should move effortlessly, with both pull from the front end and drive from the back end. The topline of the dog (that is, the line of the back) should move smoothly when viewed from the side. The legs should be straight, without turned-in hocks or turned-out front feet. 

The Jack Russell’s head “should be well balanced and in proportion to the body. The skull should be flat, of moderate width at the ears, narrowing to the eyes.” There should be a defined but not overly pronounced stop—the area where the muzzle meets the skull. “The length of the muzzle from the nose to the stop should be slightly shorter than the distance from the stop to the occiput,” which is the back of the skull. “The nose should be black. The jaw should be powerful and well boned with strongly muscled cheeks.” 

The dog’s eyes should be almond-shaped, dark, and “full of life and intelligence.” The ears are “small, V-shaped drop ears carried forward close to the head.” The ears should not stand up straight nor be thick and large like hound’s ears. 

The mouth of the Jack Russell Terrier has strong teeth and a scissors bite, which means the top teeth overlap the lower ones. A level bite, where the upper and lower teeth meet, is also acceptable. The neck of the Jack Russell is “clean and muscular, of good length, gradually widening at the shoulders.” The good neck allows the dog to spar with quarry below ground and adds to his athleticism while at work. 

“The chest of the Jack Russell Terrier should be shallow and narrow and the front legs not set too widely apart, giving an athletic rather than heavily chested appearance.” The chest needs to be flexible and compressible to enhance the dog’s ability to work up close to the quarry in bending and winding narrow tunnels below ground. A large chested dog is limited in hunting below ground because he cannot fit in a narrow earthen den. 

“The back should be strong, straight and, in proportion to the height of the terrier, giving a balanced image. The loin should be slightly arched.” In other words, the entire structure of the dog is designed for strength, to able to hold up under hard work and move efficiently. The feet of the Jack Russell Terrier need to be “round, hard padded, of cat-like appearance, neither turning in or out.” The dog needs strong feet for digging and crossing varied terrain. 

The tail “should be set rather high, carried gaily and in proportion to body length, usually about four inches long, providing a good hand-hold.” The tail is cropped at about three days old so it does not break while backing out of earth, and the dewclaws are removed. The tail is sometimes used as a handle of sorts to extricate the dog from the earth. It usually requires holding the dog’s tail and hind legs to dislodge him from work below ground. 

The coat is “smooth, without being so sparse as not to provide a certain amount of protection from the elements and undergrowth.” The coat is so very important as the dog’s protection. Sometimes JRTs are in the damp ground working long hours. The coat makes an enormous difference to the protection of the dog at work. The coat seems to resist thorns and burrs, and the dog can easily shake out loose dirt. The Jack Russell Terrier may wear a rough or a smooth coat, or it could be a combination of both, known as a broken coat. A broken-coated dog may have some tail or face furnishings (longer hairs). 

As for color, the dog must be more than 51 percent white, with solid tan, black, or brown markings. White is handy to see when working in dirt with a dog who is face to face with a critter who is earth-colored. Brindle markings, made up of several different colors of hair, are not allowed because they indicate the blood of another breed.