There are a few ways that you can determine if your dog is purebred or not. The first way is to obtain a pedigree from an AKC, ACA, APRI, or CKC registered breeder. This will give you the best assurance that your dog is purebred. DNA tests can also be used to confirm whether your dog is purebred. These tests compare the dog's DNA with that of other purebred dog registries. Though not official, visually, you can look for the physical characteristics of a particular breed to determine its likely heritage. For example, if you have a Shih Tzu, they will have certain physical features that set them apart from other breeds of dogs. A veterinarian can also give you an opinion on your dog's breed.