I have a chihuahua, he is 1 pd at 9 wks....looks just like a pure breed. Are there any specific features that can determine if the dog is a pure breed or not...for example,.... spots under the tongue, spots in the mouth, nose shape, feet, i.e. Any vet's or vet techs or specialists would be appreciated. Thank you.

The only way is through parents. If you did not get purebreed papers, your dog is not a purebreed.