Because toy breeds have such a small fat reserve around their liver, they are prone to low blood sugar.  Although this can occur at any time, it is especially important to watch your new puppy due to his small size.

SYMPTOMS: Lethargy, lack of cooridination (stumbling, falling, staggering)

TREATMENT: Although you should always consult your veterinarian for proper treatment of your particular puppy, you can keep some sugar handy (e.g. Nutri-cal, Nutri-stat, vitaal, karo syrup, honey, sugar water.) to boost your little friend's blood sugar level when it starts dropping.  You must treat this problem immediately or your pup can go into shock.  To avoid this problem, do not over-play with extra tiny pups and always make sure your dog eats well and gets a good drink of water before taking them out. 

FOR BETTER OR WORSE:

You will be sharing your life with your pet. Both of you will change through the years.  Accept that your Chihuahua will change as it matures: from the cute, eager to please baby, to the disobedient adolescent, then to the self-reliant adult partner, and finally the proud but frail senior.  Be sure that you remember the promise you made to yourself and your future puppy before you made the commitment to share your life: to keep your interest in your dog and care for it everyday of its life with as much love and enthusiasm as you did the first day it arrived home.