It is very important that a person that is looking for a dog educate himself (herself) about the personality of the breed that they are interested in, and the care that the dog will require before making a decision.  This one article is a beginning.  Go to dog shows, talk to the people there about the breed that you are interested in.  Get to know the strengths and the weaknesses of the breed.  Talk to veterinarians.  Some vets will be knowledgeable about farm animals, and have only a general knowledge about dogs.  Some are specialists.  Get to know some people through a local dog club.  Talk to them about their experiences with the breed you're contemplating getting.  Owning a dog is not like owning a piece of furniture.  If what you want is something to match your interior decor, get a statue, or a painting.  There is an emotional commitment when you add a member of the family.  If you do not want to have any commitment, don't consider a Chihuahua, don't consider having a dog period.
     Since the 1950s and 1960s, breeders have focused on changing the temperament of the Chihuahua.  Temperament has been their number one priority when considering breeding.  The Chihuahua has become known for its devotion to its master (mistress), curiosity, loyalty, and trusting nature.  Chihuahuas have been known to compete in Obedience Trials, and are being used as Therapy Dogs.  They are very intelligent although a wee bit obstinate, and are trainable with patience, persistence and practice.
     Talking with some owners and breeders of Chihuahuas they emphasize the need of the dog for attention from their owners.  They call them "Velcro pets".  The Chis want to be everywhere with their owner, they want to be petted, talked to, and spoiled.  They are strictly an "indoor" breed.  They love sunbathing, but sometimes they don't know when they have overdone it.  The owner will need to watch them for heat exhaustion, or sun stroke.  The Chihuahua needs a warm, draft free environment.  They like to go on walks, but mountain climbing is definitely out, unless you plan to carry the Chi, they are extremely portable, and love the attention. When walking a Chihuahua, it is best to have the dog in a body harness rather than a collar, and never, ever in a choke chain. Be sure to fit the harness correctly, and you and your Chihuahua will enjoy many walks together. Keep an eye on the temperature outside.  If the temperature is 35 - 40 degrees Fahrenheit, it is recommended that a doggie sweater be put on the Chi.  If the temperature is below 35, better just stay home and have a good romp indoors. Running or jogging is for those big dogs, the Chi would rather be on the porch.  The Chi is a good watch dog, sometimes even after the problem is resolved the Chi will still be giving it a good yappin' at, to show who's boss.  However, the Chihuahua should not be thought of as a guard dog.  Its got the attitude but no beef to back up the bluff.
     The Chihuahua is not really good around strange dogs, nor children.  One danger is having a Chihuahua come in distant contact with a sight hound.  The sight hound will think its prey and will go after it.  Coming into contact with a cat, specifically the cat's claws, could be very dangerous to the Chi's eyes.  However, if the Chihuahua is brought up around other animals from puppy hood, it can learn to accept others and be sociable.  Children need to be taught how to handle and respect little dogs.  Dropping the Chi, or accidentally sitting on it, can kill the dog.  Chis have a molera, which is a soft spot on the top of the skull, this is also known as an open fontanel in human children.  If the Chi is struck on the head even near this spot, it also can kill the dog.
     Chihuahuas stand five inches high at the withers when full grown, and will weigh on average between four and six pounds.  Some Chis are more, others less, but if you are looking for a show dog the figures stated are good.  According to the Breed Standard, Chihuahuas are a little saucy, have a compact build, are graceful, alert and possess a little of strong "terrier" temperament.
     There are two varieties of Chihuahua.  The short coated variety appears to have been what the Chihuahua was originally.  The second variety, the long coated Chihuahua, was produced when the short coated variety came to the U.S. and was crossed to other Toy breeds - conjecture being the Papillon or the Pomeranian - being used to produce this long coat.  Short coated and long coated varieties can occur within the same litter.
     One last concern before medical conditions are listed is dental care.  Regular brushing, a routine dental checkup, and a dry food diet takes care of most problems.