Named after Parson Jack Russell of 1850-70s, Jack Russell terrier dogs have their heritage from the AKC-registered Wire-haired Fox Terrier. They are famous for their boldness to go after fox into its earthen den as well as their gentleness to let live the quarry. They are so flexible in their performance of fox hunt that they can handle underground dens efficiently with their white color that enables their fast moving bodies to be easily seen while in action.

With regard to their coat colors, they can be easily distinguished with their smooth, wiry, or "broken" coat that are mainly white with black, tan, and/or brown markings. Being work dogs themselves, Jack Russell terrier dogs show a size that ranges from 10-15 inches at the withers - or 12-14 inches in the AKC standard - as recorded in the book of standard by the Jack Russell Terrier Club of America.

The Jack Russell terrier dogs are generally perceived as alert, confident, fearless, happy-go-around, lively and very intelligent hunt dogs. However, although they're very dynamic and strong as a companion, they're not suitable - at least not the ideal pet - for everyone.

It's widely believed that if they're not well-trained they'll show their aggressiveness toward other dogs as well as other smaller household pets such as hamsters, gerbils, and cats due to their hunt dog nature. Moreover, their innate fondness to bark and dig, if not well channelled and released in outside environment, will be carried out at the expense of sacrificing some cherished home furniture.

Besides, the breed also shows the weakness in terms of shyness, disinterest, overly aggressive, lack of muscle tone, and lack of stamina or lung reserve.

On the other hand, despite its aggression shown when control is out of hand, a well-behaving Jack Russell terrier dog can make a wonderful family pet with their gentle and kind-hearted nature with people - especially with small children, who would love to be round these terriers since they're quick to learn and play a trick or two with them.

Jack Russell terrier dogs are also of great value to the owners of barns and horses. Due to the innate affinity for horses as handed down from their ancestors in fox-hunting country in England, they're very much at home in suburban and rural settings. Their fondness of being around horses, as well as going after mice, rats, woodchucks, and other pests when they're in sight, makes Jack Russell terrier dogs the most cherished asset in any residence.