The standard recognized by the AKC (American Kennel Club) is only known as "Chihuahua", but they come in two varieties, the longcoat and the smoothcoat. A Chihuahua should not weigh more than six pounds. They come in many colors, and are known for their large erect ears. Chihuahua puppies are often mistaken for hamsters because of their scrunched faces, extremely small size, and light coats.
They are thought to be descendants of an ancient, similar, but slightly larger breed associated with royalty in Aztec civilizations known as the Techichi. They are the oldest canine breed in North America.
This breed requires expert veterinary attention in areas such as birthing and dental care. They are also prone to some genetic anomalies, often neurological ones, such as seizure disorders and patella luxation. They are also known for their moleras and sensivity to eye infections.
Although they are prized for their personality and loyalty, chihuahuas are not well-suited as children's pets because of their size and physical fragility. However, their alertness, intelligence and size make them easily adaptable to a variety of environments, including the city and small apartments, and make for usually long lifetimes of 15 years or more of loving companionship.