Parson Jack Russell was a mid-19th century British fox hunting fanatic. While the dogs share some physical similarities, temperamentally they are as different as the men for whom they are named.
At maturity, Jack Russell terriers stand between 10 and 12 inches tall at the shoulders, and weigh between 11 and 13 pounds. The Teddy Roosevelt terrier has a much wider height range -- 8 to 15 inches tall when fully grown. While there is no weight limit in the breed standard, weight is proportionate to height, and the dog shouldn't be fat. Teddy Roosevelt terriers usually weigh between 10 and 25 pounds.
Coat and Colors
The Jack Russell terrier breed standard allows three types of coat. The smooth coat is flat and short. The double rough coat consists of a dense undercoat and a wiry top coat, with hairy "eyebrows" and a beard. The broken coat is a cross between the two, less dense than the rough coat and longer than the short coat, and with or without the facial hair. Jack Russells may be solid white, or white with black, brown or tan markings. The Teddy Roosevelt terrier's coat is short and smooth, and long or wiry coats disqualify animals from conformation competition. Teddy Roosevelt terriers may also be solid white, but more secondary and tertiary colors are permitted in the breed standard than the Jack Russell terrier. These additional colors include red, lemon, apricot, blue, chocolate and blue fawn, the latter a blue shade with blondish nose and eye rims.
Some people refer to the Parson's breed as the "Jack Russell terrorist." There's a reason for that -- Jack Russells often don't get along with other canines; they are known to kill cats, bark and dig like mad; and they need an incredible amount of exercise. However, if you're looking for a working terrier, consider this one the "Jack Russell Treasure." The Teddy Roosevelt terrier is basically a short-legged version of the rat terrier, a breed recognized by the American Kennel Club and the UKC. The Teddy Roosevelt terrier's lineage contains fox terrier, beagle, Italian greyhounds and whippets. Inheriting the temperament of some of these breeds, he's far more congenial with dogs, cats and kids, and makes a better family dog than the Jack Russell terrier.
Exercise and Training
Both breeds are working dogs, bred to kill vermin. Neither is a canine couch potato. The Teddy Roosevelt terrier is easier to train than the Jack Russell, with the latter needing consistent training to appropriately channel all his energy. Both breeds do well in canine sports such as Flyball and agility, and especially excel at earth dog trials, where they can perform the job for which they were bred. No matter how well-trained your Jack Russell or Teddy Roosevelt terrier is, don't take either for walks off lead. Their strong prey drive means they're likely to take off after any rabbit or squirrel crossing their paths.