i have 2 long haired, my grandfather bred them for 35+ years and im now comming into the breeding world.
some things to rember with any chi...teacup as was already said...walk straight away form anyone selling teacup, micro or "rare" chis...also try and steer clear of anyone selling taco bell like chis (the head shape is NOT correct for the breed and all with the "deer head" should be spayed/neutered.
the chihuahua standard calls for a dog of 2-6 lbs, id suggest to nayone new to the breed to look for puppies from a mother of around 5-6 lbs and a father of anythign from 3-4 lbs, this will give you an "average" size chi...5lbs is usually a great weight for a chi small wihtout being too small, any breeder breeing their females to a malre larger than them, again walk away (this breed is prone to alot of pregnancy problems and the male should ALWAYS be smaller than the female) and any breeder breeding females under 4lbs should again just be walked away from.
chihuahua puppies are very fraigile, they should NOT be allowed to jump off beds or sofas as they can hurt their legs or their heads/necks. (i have a ramp against the couch and one at the side of my bed so my chis can safley get on and off things. they are prone to hernias...(usually avoidable in good breedings) luxating patella (knee problems again usually avoidable in good breeding) and hypoglycemia (any puppy upuntill about 6 months should be fed litle and often (or free fed) and nutrical or similar product should be kept on hand at all times just in case...hypoglycemic shock can kill them. however a well bred adult chihuahua tends to be fairly healthy and sturdy little dog.
keep an eye on puppy teeth as chis tend to retain them, these retained puppy teeth can easily be removed at the time of spay/neuter for low cost.
personality wise, these are tenacious little dogs prone to terrier like attitudes, they can be EXTREEMLY stubborn and tend to be a little difficult to housebreak. they are quick to learn "tricks" however tend to prefer to use them when they want rather than when asked...my female quickly learnt sit up (beg) however now instead of doing it when asked she sits by the dinner table and does it when we dont pay attention she barks to gain it. they are WONDERFULL at finding ways around the rules.
they are GREAT watch dogs...any strange noise (or familiar noise that usually involves doorbells/knocking at the door) they will alert you to it with a fairly loud deep bark for their little size. though they are often refered to as yappy dogs, they have a big bark for the size of their boddies. however they do need some training when it comes to the stopping part of telling you theres someone at the door!
these are clannish dogs, if you have nother dog breed in the house expect them to be a litle standoffish for a while...however they generlaly get along great with other chis. they also tend to bond especially with 1 person and can be VERY protective of that person. they do require lots of early socialization to avoid the potential of having an agressive dog. they may be small but they have a big bite.
excersize wise they can get plenty just running round the house, they do like a walk or a romp in the yard, but in bad weather no worries they can get plenty of excersize tearing up and down the hallway. chis are prone to "zoomies" usually around bedtime where they will literally bolt round the house for a few minutes...
they do HATE the cold and actually apreciate a sweater in incliment weather (mine have a basket with sweaters in and they will bring me a sweater if there cold for me to put on (and i dont ask them or give them any other kind of incentive) mine wont even leave the house when the weathers bad (which happend alot here in ct) on the good side though they are fairly easily litterbox trained (i use a puppy pad in a large litterbox) this is alos handy for mine as they come down to the sailboat with us and theres alot less oportunities for potty break on the boat.)
htey do need a firm hand however yelling and screaming wont get you anywhere, a good training method for chis is ignoring them, they want your attention every moment (unless there doing something bad) so if you catch them in a bad act a firm no followed by complete ignoring them (no eye contact or talking ot them for a few minutes) usually teaches them the lesson.
as always a spayed/neutered dog is a better dog, an unaltered chi is very prone to dog agression, someone forgot to thell them they were so small...these are BIG dogs in little bodies and an unneutered male will happily chase down and try an attack a rotty on his territory.
coat lenght is personal preference, short coated chis shed more than long coated chihuahuas, a long coated chihuahuas hair takes about 3 years to reach its full length, im partial to long haired chis, short haired are cute however long haired chis have a softer look about them, and always look puppyish...however some people prefer the sleak look of the short haired chi.
grooming of both types is usually minimal, short haird chis do well with a zoom groom to remove dead hairs from the coat, long coated tend to require a comb. there are chis with whats refered to as "medium" coat, these dogs tend to be longer than a short haired, sorter than a long haired and dense (usually with an undercoat) or theres a "double haired long" (a long coat with an undercoat) either of these 2 require a little more in the ways of grooming, a regular long coated chi requires no more brushing than a short coated chi as they dont tend to mat like most long haired breeds. however long coated tend to require sanitary clipping every so often around their private parts and under their tails)
bathing shoudl be kept to around once a month with a mild shampoo.
go wiht the coat lenght you prefer as either way doesnt make much of a difference in upkeep.
these dogs do bond firmly though so make sure you do ALOT of reaserch and know this is the dog for you! these are a long lived breed expect to be with it for 15+ years, and they bond very strongly with you so any kind of seperation is very painfull. these are not a breed that does well in a rehoming situation or being left alone for long work days. this breed is prone to seperation anxiety.
the only down side i realy have with the breed is...chis are like potatoe chips...you cant have just one...there very addictive, and if going to be left alone for longer periods it might be a good idea once your first is housetrained (around 6month-1yr) to get a second to keep it company. suprisingly these are pack dogs and like the company of their own breed.
hope this information helps, there are some good chihuhaua specific boards out there also which if youd like to know about PM me (i dont like advertising on other peoples boards) and id be more than happy to answer any other questions you might ahve about this breed, ive been involved with chis my entire life and grew up with a pack of usually 15-20 chihuahuas (not including current litters) and currently have 2 of my own.
oh and while its very tempting to carry these little dogs everywhere...belive it or not there dogs and need to be treated as such, they actually LIKE to use their own legs once in a while...let them walk first, belive me theyll let you knwo when they want up... dodger just sits and refuses to move once his legs are tired...vixie however actually paws at my ankle till i pick her up...
ive included pics of my 2
DODGER 8 month old 3lbs long haired blue fawn male.
VIXIE, 1 1/2 yr old 5lb 4oz long haired red and cream female