The long haired Chihuahua is adorned with a plume tail, collar over the chest and stripes on the ears and limbs. 
The small Chihuahua is a well balanced dog with its typical bold expression, and skull round as an apple (with or without fontanelle, which is a small dent over the skull). The Chihuahua should not weigh more than 3 kg. The body is slightly longer than tall; in the male a shorter body is desirable. The eyes are large and round, very expressive, never protruding and dark; ears are large and erect in alert, inclined to a side when at ease; split or cropped ears disqualify. The neck is slightly arched; the ribcage wide, but not barrel shaped; the tail is moderate length, high implanted, carried in elevation, arched or in semi circle with the tip directed towards the back; the tail should never be carried between the legs, or be docked. There are two coat varieties: short and long hair. The long hair is soft in texture, straight or slightly wavy with undercoat and stripes at the ears, neck, tail, legs and feet; it should not seem nude due to fine hair. The short hair is soft, flat on the body and shiny, with allowed undercoat; a hairy tail is preferred. Every color is accepted in all their tonalities and combinations.
The short haired Chihuahua has a dense hair, easy to care for, without the stripes from its long haired sibling. 
Considered the smallest of dog breeds, the Chihuahua is a necessarily home, gentle dog.  A dog that is not aware of its size, and the large dog Chihuahua bark, clearly prove that it is a self confident dog. However it is described as reserved and more comfortable around its own breed. It is territorial and protects its master with all of its heart. The Chihuahua loves a good life and doesn’t mind attention and pampering. To avoid an aggressive adult with a tendency to bite, it is advisable to socialize the Chihuahua with friends and other dogs.
No puppy is as delicate as the Chihuahua, the smallest of dogs. The open fontanella over the head makes vulnerable to serious injury.
An eight week Chihuahua weighs around 500 g. Growth in this tiny breed depends on the breeding line. Usually, maturity is reached after a year. A popular indication for the adult weight is doubling the weigh it has at three months. When choosing a specimen the smallest should be avoided, since these are more prone to health problems. The buyer should watch for good head structure and avoid a skull that is not completely formed (without considering the fontanelle, which is allowed by the standard). A compact dog should be sought, with an extrovert and confident personality. Shyness and nervousness can lead to serious problems as an adult. The adolescent is charming to its owners. The temperament is still balanced, but desire to play persistently stands out. The coat and color barely change.
Surviving every breed, the Chihuahua, powerful but not soft, will surely inherit the earth. 
The Chihuahua is a breed with noticeable longevity that can reach 20 years. However, there is a series of problems that affect the breed, including cleft palate, secondary glaucoma, hemophilia A and several heart valve problems, although all of them with limited incidence. Kidney stones, hydrocephaly and pulmonary stenosis are informed, but are not alarming or common. Shoulder dislocation has also been reported. The owner should know that the fontanella, an open hollow over the head, is accepted in the breed and requires delicate handling. Naturally, the long haired variety requires more care than the short haired, but both are easy to care for, feed and provide exercise. Hypoglycemia is also reported in the breed.