<P> Jack Russells are first and foremost a working terrier . Originally bred to bolt foxes from their dens during hunts, they are used on numerous ground - dwelling quarry such as groundhog, badger, and red and grey fox . The working JRT is required to locate quarry in the earth, and then either bolt it or hold it in place until they are dug to . To accomplish this, the dog will not bark but will expect attention to the quarry continuously . Because the preservation of this working ability is of highest importance to most registered JRTCA / JRTCGB breeders, Jack Russells tend to be extremely intelligent, athletic, fearless, and vocal dogs . It is not uncommon for these dogs to become moody or destructive if not properly stimulated and exercised, as they have a tendency to bore easily and will often create their own fun when left alone to entertain themselves . </P> <P> Their high energy and drive make these dogs ideally suited to a number of different dog sports such as flyball or agility . Obedience classes are also recommended to potential owners, as Jack Russells can be stubborn at times and aggressive towards other animals and humans if not properly socialized . Despite their small size, these dogs are not recommended for the condominium or apartment dweller unless the owner is ready to take on the daunting task of providing the dog with the necessary amount of exercise and stimulation . They have a tremendous amount of energy for their size, a fact which can sometimes lead to trouble involving larger animals . They may seem never to tire and will still be energetic after their owner has called it a day . While socialised members of the breed are friendly towards children, they will not tolerate abuse even if it is unintentional . </P> <P> The breed has a reputation for being healthy with a long lifespan . Breeders have protected the gene pool, and direct in - line breeding has been prevented . Jack Russells can live from 13 to 16 years given proper care . However, certain lines have been noted for having specific health concerns and, therefore, could occur in any line or generation because of recessive genes . These issues can include hereditary cataracts, ectopia lentis, congenital deafness, patellar luxation, ataxia, myasthenia gravis, Legg--Calvé--Perthes syndrome, and von Willebrand disease . </P> <P> Being a hunt - driven dog, the Jack Russell will usually pursue most creatures that it encounters . This includes the skunk, and the breed is prone to skunk toxic shock syndrome . The chemical in the skunk spray is absorbed by the dog and causes the red blood cells to undergo haemolysis, which can occasionally lead to fatal anaemia and kidney failure . If sprayed underground, it can also cause chemical burning of the cornea . Treatments are available to flush the toxin out of the dog's system . </P>

What's the lifespan of a jack russell terrier