Terrier toby jug produced in Japan circa 1950. Terrier is a type of dog originally bred to hunt vermin. A terrier is a dog of any one of many breeds or landraces of the terrier type, which are typically small, wiry, game, and fearless. Terrier breeds vary greatly in size and are usually categorized by size or function. There are five different groups of terrier with each group having different shapes and sizes. This terrier's tail curls up to form the handle of the jug.