German shepherds are intelligent, capable and loving dogs, that go through many stages on the road to maturity -- five distinct stages in their first year alone. The long adolescent period that ends the puppy years is highly individual, but most dogs mature somewhere before 3 years of age.
The Neonatal Stage
This is the very earliest stage your German shepherd will pass through. Simply put, this is the helpless baby stage when your puppy's eyes will still be closed and he is completely dependent upon his mother. She will feed him, wash him and clean up after his accidents for the first two or three weeks. His eyes will open at around 10 days. At this time, your puppy is little more than an eating machine -- filling his belly to help his tiny body grow and develop.
The Transitional Stage
Though it is short and indistinct, the transitional stage from the neonatal to the socialization stage is important to your pup's development nevertheless. This brief phase -- lasting only about a week after his eyes open -- marks the period when your German shepherd begins to notice his environment. He will start to look at things curiously and be aware of sounds around him. Prior to this he has been in his own little world with no sights or sounds beyond his own body and that of his mother. When his eyes open, the immediate environment -- with other living beings -- is suddenly a part of life that he must face.
The Socialization Stage
At around 3 weeks, your puppy begins to learn how to interact with others -- both animals and the humans around him. He has already had some practice with dogs through the daily contact with his mother and litter mates, but now he begins to expand his circle of acquaintance to other dogs or cats in the household and to the family of humans around him. This is the most critically important phase in your German shepherd's development and helps decide his later suitability for work in rescue, service or as a family dog. At this time, he should have opportunities to meet as many new animals and faces under differing circumstances as possible, so he becomes comfortable with meeting people and other animals in a variety of situations when he grows up. This stage lasts to about 3 months of age and is the period when puppies are at their most impressionable and playful.
The Juvenile Stage
From 3 to 6 months old, your puppy will begin to look beyond the biological world of dogs, cats and people to the larger world around him. He will want to explore new places more than new faces at this point -- which may often get him into trouble. This is an active and trying age for puppy parents. Your puppy looks like a mostly grown-up dog but behaves entirely like a pup. His attention span is about as long as that of the average teenager, so this is not a particularly easy time for obedience classes. Your shepherd will have other things on his mind, but pet parents should continue to persevere because this is the best stage to resolve any obvious aggression or anxiety issues your pup may display. If those issues are not addressed early, they could become larger problems later on. To make things a tad more difficult, at around 5 months of age, your German shepherd starts to mature sexually.
The Adolescent Stage
The teenage angst that human children go through is roughly equivalent to what pet parents can expect from their adolescent German shepherd. Beginning with the onset of sexual maturity and lasting through the first two years of his life, your puppy's hormones will rage uncontrollably unless he is neutered early. This stage is usually marked by mounting -- anything and everything -- marking his territory and even fighting with other male dogs. Females will enter their first estrus period at this time and may try to escape the yard or otherwise pose problems. The pup's body has become adult, and his brain is fully alert and capable, but his emotions are still in the turbulent transitional phase from teenager to full adult. If he were human, this would be the stage at which you would hide the car keys.
The Adult German Shepherd Dog
At around 3 years of age, you can begin to relax. As an adult, your German shepherd is finally the calm, dignified, courageous and respectful dog you always knew he would grow up to be. If you were patient and dedicated through those early, sometimes difficult, years, you now have a well-trained and disciplined companion for life. Congratulations.