Originally bred in the 19th century by Parson Jack Russell, an avid hunter, selected traits that would assist him in hunting. Working dogs, Jack Russell Terriers were bred to be fearless and feisty to flush out prey from the forest, particular foxes. As a working dog, Jack Russell Terriers tend to have an athletic build and boundless energy. Jack Russell Terriers are very intelligent, but also willful and stubborn, which can make them extremely difficult to train without consistency.

As a hunting and working dog, Jack Russell Terriers do have the hunting instinct in them and have been know to consider smaller household pets prey. However, this does not mean that they cannot be good family pets. Jack Russell Terriers are usually very good with children and gentle with them if they understand how to approach dogs. Jack Russell Terriers live 15 years or more. They grow to an average 10 to 12 inches in height and 14 to 18 pounds in weight. Jack Russell Terriers have several different types of coats of the shorthaired variety (some are smooth, some are not) but all are easy to maintain with regular brushing.

Jack Russell Terriers are suited for all kinds of living, but do need to be exercised regularly, at least once a day, due to their seemingly boundless energy. Without regular opportunities to exercise and play, they will become bored and begin to bark at everything and become destructive. If a Jack Russell Terrier must be left alone for an extended period of time without the opportunity to exercise, it is recommended that they be crated until it is possible to let them exercise.

Jack Russell Terriers are fearless and will run off without thinking. A fenced in area is a must for a Jack Russell Terrier, but the fence needs to be deep enough as they are diggers, and tall enough to not jump over. An average sized Jack Russell Terrier can jump five feet quite easily. There are some health concerns with the breed. Some Jack Russell Terriers are prone to dislocation of the kneecaps, inherited eye diseases, deafness, Legg Perthes - a disease of the hip joints, and cataracts. Currently, there is some dispute about the breed and breed standards. The AKC does not officially recognize the Jack Russell Terrier, considered a working dog. It only officially recognizes the Parson Russell Terrier.