Named for the 26th president of the United States, Theodore Roosevelt, the breed has been referred to in the past as Bench Legged Feist, Treeing Feist or Squirrel Feist. The United Kennel Club recognizes it as the Rat Terrier. It was developed from crossing several breeds such as the Feist, Bull Terrier, Smooth Fox Terrier, Whippet, Italian Greyhound, Manchester Terrier and the now extinct English White Terrier, as well as the Beagle and the Pembroke Welsh Corgi. It has a height standard of 8 to 15 inches. Muscular and well-proportioned, the Teddy Roosevelt Terrier is low-set. Its head is broad, wedge-shaped and slightly domed. It has V-shaped ears that are carried either erect or button. It has a black nose with a moderate stop. The chest is broad and deep and it has a slightly arched neck that blends smoothly into well laid back shoulders. It has small eyes that are round to almond shaped. The tail can be docked or left natural carried in an upward curve. Its coat is made of short, dense and smooth hairs and comes in solid white, or other solid colors with markings. It may also come in white with a variety of coloured patches.
Typical of a terrier breed, the Teddy Roosevelt Terrier has a keen sense of smell and high level of intellect. They were originally used as ratters. They are energetic, alert and have excellent endurance especially when on the hunt. They thrive on human companionship and are devoted family pets. They have strong protective instincts and can get along well with children and other dogs of similar size. They can live for about 15 to 16 years.