The smallest breed of dog in the world is a Chihuahua. Many of these dogs have held World records for being the smallest dog of all, but the breed itself can be considered the smallest of all dog breeds. It ranges in weight from 1 to 6 kilograms and stands 15 to 23 centimeters at the shoulder.

The Chihuahua is named for the state in Mexico where the breed was first discovered. There are a couple of theories about how this breed made it onto the world scene. One is that the Chihuahua is a descendant of a companion dog to the Toltec people called a Techichi; a dog believed to be the oldest breed in the Americas. The Techichi, however, was a bigger dog, and the diminutive size of Chihuahua is thought to be a result of cross breeding between it and small Chinese dogs brought over by the Conquistadors.   It became a recognized pure bred by the American Kennel Club in 1904.

As a breed, the Chihuahua is vulnerable to several health conditions including hydrocephalus, seizure disorders and hypoglycemia.They are known to be loyal companion dogs, but can be a biting risk for homes with very small children, so it is recommended that a Chihuahua be brought into homes with school aged children and adults.

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