Is a Feist a Rat Terrier?

No, a Feist is not a Rat Terrier according to the AKC, which recognizes Rat Terriers as a distinct breed, but not Feists, and according to the UKC and CKC, which accepts the Rat Terrier, Mountain Feist, and Treeing Feist as unique and distinct breeds. 

Despite some recognition of two breeds of Feist dogs, largely, the word “Feist” is a catch-all term for small mixed-breed terrier dogs who were bred to hunt and tree small game around farms and in the woods of the southern and Appalachian regions of the U.S. Often, these crosses involve Rat Terriers, but most don’t consider a purebred Rat Terrier to be a Feist.