The Rat Terrier is a small to medium-sized dog breed known for its energy, intelligence, and affectionate nature. These dogs typically weigh between 10 to 25 pounds and stand around 10 to 18 inches tall at the shoulder. Rat Terriers are characterized by their short, smooth coat that can come in a variety of colors, including white, black, tan, or a combination of these. They have expressive, alert eyes and ears that can stand erect or fold over.