The Chihuahua is in the toy breed group and its classification is a lapdog, companion.
It has now been proven via DNA evidence that the Chihuahua originated from the ancient Techichi dogs of Mexico.
This breed got its name from the state of Chihuahua, Mexico, thought to be the major border crossing when this dog was brought into the United States.
Litter size can range quite a bit and in rare cases a Chi can have 6 pups; however, the average sized litter is 1-3 puppies.
This breed has more Cesarean sections than any other due to the Chihuahua newborn's extremely large head in relation to his body and the narrow width of most female dams.
According to a 20 year long study by the University of Georgia, the 3 top leading causes of death for the Chihuahua breed are - in order - cardiovascular disease, trauma and infection.