All dogs go through growth cycles that encompass the same stages. What varies from breed to breed is not the time frame of each stage, but the degree to which dogs exhibit certain physical or social characteristics within each stage, such as the development of muscle or guarding tendencies. Chihuahuas are a "toy" breed. Alert, active and intelligent, they are good city dogs, requiring minimal exercise. They're inherently loving and good with families, as long as children are patient and gentle with them.
Neonatal Stage (Birth To 2 Weeks Old)
Chihuahua puppies weigh between 71 to 156g. at birth. Their eyes are closed, but touch and taste are present. They do nothing but eat and sleep. Because they're unable to regulate their own body temperature or relieve themselves, their mother snuggles them and stimulates elimination by licking their genitals. Larger chihuahua pups can weigh 383gr. by the end of this stage.
Transitional Stage (2 To 4 Weeks Old)
Pups' eyes open and they see very well by 3 weeks old. Hearing and smell develop and their teeth break through their gums. They stand, clumsily walk a little, wag their tails and even bark. Pups younger than 3 weeks can't learn anything, not even from their mother. By 4 weeks old, Chihuahua puppies weigh between 198 and 595gr.
Socialisation Stage (3 To 12 Weeks Old)
This stage overlaps their transitional stage and Chihuahua puppies begin socialisation at 3 weeks old. They get curious, more aware of their surroundings and explore, experiencing real fear between 8 and 10 weeks old. Alarmed by normal objects and experiences, they soon refine their social skills, also improving their physical skills and coordination. They explore litter hierarchy and have full use of their senses by 9 weeks, when they truly begin to focus on people. Even so, pups removed from the litter too early often have socialisation problems with dogs later in life. Many Chihuahua breeders won't place pups younger than 3 months, when the socialisation stage ends. By this time, Chihuahuas weigh between 0.454 and 1.36kg.
Ranking Stage (3 To 6 Months Old)
Chihuahua puppies view all companions, including other pets and humans, as their "littermates." They're most influenced by this family and hone their understanding and use of dominance and submission ranking. Teething promotes lots of chewing! Pups between 3 and 4 months assert their independence. They wander from the "nest" and get into mischief, experiencing another fear stage at 4 months old. Human and dog decide who's boss. Serious training and discipline has to begin. For best results, the Chihuahua pup must feel he's a very important individual. By 6 months, he weighs between 42.5 to 142g.
Adolescence Stage (6 To 18 Months Old)
Chihuahua puppies remain most influenced by their human and dog "pack" members. They exhibit another chewing phase between 7 and 9 months old. This is part of exploring their territory. There's heightened exploration of dominance. More dominant chihuahuas fully assert themselves, often challenging their owners. If pups aren't spayed or neutered, this stage has the beginnings of sexual behaviour. Chihuahuas vary greatly in size and by 18 months most have reached their adult weight, between 0.907 and 2.72kg.