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. 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. The current UKC standard calls for a Teddy Roosevelt Terrier to be 8–15 in (200–380 mm) in height, with weight proportionate to height. Teddy Roosevelt Terriers weighing as much as 25 lb (11 kg) or as little as 8 lb (3.6 kg) are not uncommon.