The Teddy Roosevelt Terrier is a small to medium-sized American hunting terrier. It is lower-set, with shorter legs, and is more muscular with heavier bone density than the related American Rat Terrier. Much diversity exists in the history of the Teddy Roosevelt Terrier breed, and it shares a common early history with the American Rat Terrier, Fox Paulistinha, and Tenterfield Terrier. The Rat Terrier's background is said to stem from the terriers or other dogs that were brought over by early English and other working-class immigrants. Since the breed was a farm, hunting, and utility dog, little to no planned breeding was used other than breeding dogs with agreeable traits to each other to produce the desired work ethic in the dog. The Feist (dog), Bull Terrier, Smooth Fox Terrier, Manchester Terrier, Whippet, Italian Greyhound, the now extinct English White Terrier, Turnspit Dog, and Wry-legged Terrier all share in the Teddy Roosevelt Terrier's ancestry. These early ratting terriers were then most likely bred to the Beagle or Beagle crossbred dogs and other dogs. Maximizing the influences from these various breeds provides the modern Teddy Roosevelt Terrier with a keen sense of awareness and prey drive, an acute sense of smell, and a very high intellect. Although they tend to be aloof with strangers, they are devoted companion dogs with a strong desire to please and be near their owners at all times.