Named after the Chihuahua region of Mexico, Chihuahuas are the oldest canine breed in North America. It is believed that they are descendants of a slightly larger breed known as the Techichi which were associated with Aztec royalty.

Although the American Kennel Club recognizes a single Chihuahua breed, there are two distinct varieties: the smoothcoat and the longcoat. Considered the smallest breed of dog, it has an apple-shaped head with a short, pointed muzzle, tiny dark eyes and large erect ears. Chihuahuas are often prized for their diminuitive size.

It is important to note that Chihuahuas require expert veterinary attention in areas such as birthing and dental care. They are also prone to some genetic anomalies, often neurological-related, such as seizure disorders and patella luxation. The breed is also known for the moleras­a soft spot on the top of the skull, similar to a fontanelle in human babies­and sensitivity to eye infections.