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. Separating the long-legged phenotype from the short-legged phenotype in most cases did not occur, litters born from parents of either or both phenotypes commonly displayed a variety of leg and body length, yet all were still considered and labeled merely as Rat Terriers. In the middle 1990s, efforts to segregate the types began in earnest, but mixing of the two types in some cases still exists today.