The Toy Manchester Terrier is a smaller variety of the Manchester Terrier. Its ancestor, the Black and Tan Terrier was developed in the now outlawed sport of rat baiting, where dogs were bred to be small since a smaller dog would have to kill less rats in the same time given to larger dogs. A Black and Tan Terrier weighing just over 5 pounds named Tiny managed to kill 300 rats in less than an hour.
Although the two breeds look similar, they were bred separately, with the Toy Manchester Terrier being a later miniaturized version of the American Manchester Terrier. Despite this distinction, The United Kingdom Kennel Club has opened the stud books to American Kennel Club registered Toy Manchester Terriers to increase numbers of their Black and Tan English Toy Terrier. Although previously a separate breed, the Toy variety was added to the Manchester Terrier breed by the American Kennel Club in 1959.