The Chihuahua is included in the smallest breed of dogs, which one originated in Mexico and the term of Chihuahua had derived from the state of Chihuahua in Mexico. The exact origination theory has been puzzling from the earliest period among the animal experts, who devised the perfect origin of several breeds of dogs. This breed most probably derived from the earliest ancestors of Techichi which one was the most favorable companion dog of Toltec civilization in Mexico. This smallest breed of canine has the several physical characteristics on the basis of its physical shape & size.

The Chihuahuas are found in various colors, coat lengths, head shapes and sizes considerably after once noticed it, so intensively by someone some ever. In the investigation of the Chihuahuas varieties for its heads such as found in the sizes of apple head and deer head which had the evidence of such breed existence in Mexico surely. According to the investigation of this Mexican breed of dog by the animal experts who have divided it into two categories such as the smooth coat (short haired) and another one is long coat. This standard smallest breed has not inherited too much height considerable which limited between 15 and 23 cm and some other dogs grow up to 30-33 cm approximately. Almost of the Chihuahuas are not found the weight more than 2.7 kg. It has several colors combination such as solid black, solid white, spotted, sabled, red, cream, brown, chocolate, etc. It has the average life span considerably such as 15-20 years.