The Jack Russell is a happy, bold, energetic dog; they are extremely loyal, intelligent and assertive. Their greatest attribute is their working ability, closely followed by their excellent qualities as a companion. A Jack Russell can be equally contented bolting a fox or chasing a toy in your living room, or equally adept at killing a sock in the living room or a rat in your barn. Their funny antics will continually amuse you, their intelligence seems to know no bounds and their assertive nature and boundless energy can at times be overwhelming (therealjackrussell.com).