Chihuahuas are very small dogs, and are the smallest breed recognized by some kennel clubs.There are two main varieties recognized by kennel clubs, the short-haired and the long-haired. There is a second varietal split as well, having to do with the shape and size of the dog's head. These two descriptive classifications are apple head and deer head, but only the apple head is conformationally correct.
Breed standards for this dog do not generally specify a height; only a weight and a description of their overall proportions. Generally, the height ranges between 15 and 23 cm (6 and 9 in);1 however, some dogs grow as tall as 30 to 38 cm (12 to 15 in). Both British and American breed standards state that a Chihuahua must not weigh more than 2.7 kg (6 lb) for conformation.1 However, the British standard also states that a weight of 1.8?2.7 kg (4?6 lb) is preferred  and that if two dogs are equally good in type, the more diminutive one is preferred.