The rat terrier was developed as a working dog to hunt and catch pests, such as rats, on farms. The breed descends from other terrier breeds, including the fox terrier, bull terrier, Manchester terrier and old English white terrier.
In the 1910s and 1920s, new traits were introduced — for example, Midwestern farmers needed to control jackrabbit populations, so dogs were crossbred with whippets and Italian Greyhounds. In the American Southwest, beagle lines were introduced to improve hunting abilities and encourage a pack mentality. A miniature rat terrier was introduced in the 1920s when rat terriers were bred with toy fox terriers.
While considered quite common when they were first introduced, the rat terrier is now considered a rare, small dog breed. Their popularity waned as farmers began to use poison to control pests in the 1940s and ’50s.