The Rat-Cha is a cross between the American Rat Terrier and the Chihuahua. While the American Rat Terrier is now a relatively uncommon breed, the Chihuahua is popular as a "purse" pet and features in popular culture.
A small dog, the Rat-Cha is used to indoor living and being in close proximity with its owner. Terrier-like qualities such as fearlessness and self-possession cna be found in the Chihuahua, although there are only a few "knowns" about the breed, such as its place of origin (state of Chihuahua in Mexico).
The American Rat Terrier, closely identified with feists, is mostly found in rural southern US, where it was originally bred for vermin control. Quick and hardy, this breed soon endeared itself to its owners and became a valued family pet as well.