The Rat Terrier is an American farm dog, developed in the late 1800s and early 1900s from English terriers and feists, with Whippet speed and Beagle scenting added later. Farm families kept them to clear barns of rats and chase squirrels. They come in miniature and standard sizes, always with white in a short, smooth pied coat.
Many are cheerful, affectionate and eager to stay near their people, and often a bit more biddable than other terriers. Prey drive, quick reflexes and a love of digging come along too, so a squirrel on a San Bernardino sidewalk can beat even good recall. Dogs vary, and training and history matter as much as breed. Expect a long-lived, portable companion that needs daily activity and secure fencing.