The Jack Russell terrier stands between 10 and 15 inches high at the shoulders and weighs between 14 and 18 pounds. The breed standard calls for a compact, balanced appearance.
Jack Russell terriers were originally bred in England by the Reverend John Russell, using the descendants of a female terrier named Trump. Jack Russell terriers were recognized as a distinct breed by the 1850s.
The Jack Russell Terrier Club of America is the major breed association and registry for Jack Russell terriers in the United States. Jack Russell terriers are still used for hunting ground-dwelling quarry and are also popular for agility competitions and canine sports such as flyball.