Weight, Height & Life Expectancy Jack Russell Terriers are approximately 25-38 cm tall, and weigh between 6-8 kg. You can expect to enjoy at least 13-14 fun-loving years with a Jack Russell Terrier. Personality Jack Russell Terriers are extremely smart, loyal and strong-willed. They are often described as a “BIG” dog in a little dog’s body. They are feisty, active and can sometimes “borrow trouble” by climbing and jumping up over fences, particularly if they are restless and are not exercised or engaged enough. Plenty of game playing, training and exercise will keep this fun-loving dog stimulated and happy. In return, you’ll be amused by your little friend’s bold and funny antics. Grooming and Exercise Jack Russell Terriers require minimal grooming, although care should be taken in combing their coat where it is long. At minimum, they need at least 30 minutes of exercise each day, and thrive in open spaces ...