History

The Chihuahua is the oldest breed of dog in the Americas, and the smallest breed in the world. Its name originates from its Mexican state of origin, but the Chihuahua’s history is fairly unknown. It’s thought to have been bred from the Fennec fox because of its small size, wide eyes, and big ears, but its exact origin is a mystery. These guys were prized pets of the upper classes in pre-Columbian Indian nations, and weren’t brought to Europe until the end of the nineteenth century.

Personality 

A Good Pal
The Chihuahua is a good companion and enjoys being around people. He’s extremely loyal and good-natured—a good thing, because it’s hard to be around a Chihuahua without wanting to pick him up.
Smart and Energetic
Chihuahuas are intelligent dogs that learn quickly to obey and react well to positive reinforcement.  They have a lot of energy and are very agile.
A Chihuahua Likes His Own Kind
These little guys need to be watched around young kids and other dogs. They require a lot of patience when getting used to children, but can learn to get along well with anyone. When it comes to hanging out with other dogs, they prefer the company of their own breed, but again, with a little bit of patience and care, they can hang with anyone, even the enormous Great Dane!

Care

City Slickers
The Chihuahua is a good choice for apartment dwellers because of his tiny size. He’s well-adapted to city living, though he does need a little space to roam around. He dislikes the cold and does best in warm weather.
A Little Exercise
Even though it’s tempting to carry your tiny Chihuahua, he still needs to be walked like any other dog. A good stroll once a day will give him the exercise he needs, and he loves a game of fetch in the park just as much as the bigger guys.
Coat Care
Your Chihuahua can wear his coat long or short, depending on how often you want to tend it. Long coats need daily attention, while short-coated Chihuahuas can get by with the occasional brushing.
The Chihuahua is called a “purse dog” for a reason: he’s pretty much pocket-sized, and can be easily transported in a reasonably roomy purse. Among the more well-known Chihuahuas who have enjoyed this mode of transportation is Tinkerbell, Paris Hilton’s purse-riding pup.