The history with the Chihuahua is uncertain. The Doggy is named once the Mexican state of Chihuahua, wherever the dog was identified about 1850. Some gurus Believe the Aztecs or Incas formulated the Canine; others say the breed can be traced to Spanish dogs way back to the 1500s. The use of the Chihuahua way back also is unsure. Some Believe Chihua