An American Yorkshire terrier and rat terrier mix is referred to as a ratshire terrier by the Designer Dogs Kennel Club. It's not a purebred dog but a hybrid between two purebred breeds.
The ratshire terrier ranges from 5 to 15 pounds and has an average lifespan of 14 years. It can have a short to medium coat of hair that's relatively low maintenance. The coat is most often black and tan with a few areas of white around the mouth, belly and feet. This crossbreed is typically alert, energetic and sweet. They need a short burst of exercise once a day in order to keep entertained and happy.