The Rat Terrier is an American dog breed with a background as a farm dog and hunting companion. They share much ancestry with the small hunting dogs known as feists. Common throughout family farms in the 1920s and 1930s, they are now recognized by the United and American Kennel Clubs and are considered a rare breed. The social sensitivity of Rat Terriers makes them very trainable and easier to live with for the average pet owner, but it also means that extensive socialization from an early age is critical. Proper socialization of a Rat Terrier puppy includes exposing the animal to a wide variety of people and places, particularly during the first three months of life. Like most active and intelligent breeds, Rat Terriers tend to be happier when they receive a great deal of mental stimulation and exercise. Rat terriers are usually loyal to their owners and are very respectful, if they receive the proper amount of training at a young age.