For over 100 years, the Jack Russell terrier or JRT was considered merely a type of dog originating in England, but is now considered a full-fledged breed. The Jack Russell Club of America claims that JRTs do not breed true to type because of their wide genetic heritage. However, two other breeds that derive from JRTs mostly breed true to type, the Parson Russell terrier and the Russell terrier, also called short-legged Jack Russell terriers.
The most common type of Jack Russell is the smooth-coated variety. These short coats shed more often than double-coats or curly coated dog breeds. The dogs stand between ten to 15 inches from the ground to the tops of their shoulders. Eyes and noses can be any colour. Ears can be upright or floppy, called "drop ears," but drop ears are preferred. Their colour often has white in it but can vary from solid white; black and white spotted; brown and white spotted; tricoloured or patches of brown, black and white; and ticked, where dogs have black and white heads, and a body that seems to have tiny black spots speckled throughout.
Called wire-coated in other breeds, the rough-coated JRT has a long, wiry and water-resistant coat. The coat should not feel silky because silky hair will not deter wetness. Wire-haired fox terriers contributed to the making of the JRT, so rough-coated JRTs strongly resemble wire-haired fox terriers. Rough coats do not shed as much as smooth coats. With the exception of coat type, the rough-coated terrier is identical to the smooth-coated in colour and temperament.
These JRTs combine the other two coat types. They have patches of smooth coats and patches of longer, wiry coats. The wiry patches can be on the muzzle, the entire head, the legs or the body. Otherwise, it is identical to the smooth-coated variety.
The Russell Terrier
Also called "short JRTS," this breed is devoted to dogs only 10 to 12 inches tall with black noses and drop ears. The American Russell Terrier Club maintains that this is the original type of terrier that Reverend John Russell originally bred from fox terriers during the late 1800s. Other than the height, ear shape and nose colour requirements, they are physically like any other JRT. In temperament, they must have the desire to hunt and kill small game or pests, such as rats.