To better understand why your puppy doesn't listen at times, you need to understand her developmental stages. Remember that these are generalizations - each dog will progress at his or her own pace.
The Transitional Stage, 2-3 Weeks. It's during this time that a puppy's eyes open, and she slowly starts to respond to light, movement and sounds around her. She will become more mobile during this period, trying to get her feet under herself and crawling around in the box (or wherever home is). She will start to recognize her canine family and objects placed in the box.
The Almost Ready to Meet the World Stage, 3-4 Weeks
Your puppy undergoes rapid sensory development during this time. Fully alert to her environment, she will begin to recognize the humans who tend to her. It's best to avoid loud noises or sudden changes during this period. Negative events can have a serious impact on her personality and development at this time. Puppies learn how to be dogs during this stage, so it's essential that they stay with their mothers and littermates.
The Overlap Stage, 4-7 Weeks
Puppies begin the most critical social development period of their lives now. They learn social interaction with their littermates. They learn how to play and all about bite inhibition. They also learn discipline at this point from their mothers. Mom will begin weaning the pups around this time and will start teaching them basic manners, including accepting her as the leader of the pack. Pups should be handled daily, but should not be separated from either mom or littermates for more than about 10 minutes per day. Puppies removed from the family unit too early frequently are nervous, more prone to barking and biting and have a more difficult time with socialization and training. Puppies need to be left with mom and siblings until at least 7 weeks of age - and preferably a little longer - for optimum social development.
Experts say that the best time in a puppy's life to learn social skills is between 3 and 16 weeks of age - that's the window of opportunity you have to make sure your puppy grows up to be a well-adjusted dog. It is extremely important that puppy stay with her canine family during as much of this period as possible. Don't discipline for play fighting, housebreaking mistakes or mouthing - that's all normal behavior for a puppy at this stage.
The "I'm Afraid of Everything" Stage, 8 Weeks - 3 Months
This stage is characterized by rapid learning as well as a fearful period that usually pops up around 8-10 weeks. Not all dogs experience this, but most do. They can appear terrified over things that they took in stride before. This is not a good time to engage in harsh discipline (not that you ever should anyway!), loud voices or traumatic events. At this time your puppy's bladder and bowels are starting to come under much better control, and she should become capable of sleeping through the night. Simple behaviors like come, sit, stay, down, etc. can be taught now. Leash training can begin. It is important not to isolate your puppy from human contact at this time, as she will continue to learn behaviors and manners that will affect her in later years.
The Juvenile Stage, 3-4 Months
It is during this time your puppy is much like a toddler. She will be a little more independent and might start ignoring the cues for behaviors she has recently learned - just like a child does when trying to exert new-found independence. As in "I don't have to listen to you!" Firm and gentle reinforcement of commands and training is what's required here. She might start biting you - play biting or even a real attempt to challenge your authority. A sharp "No!" or "No bite!", followed by several minutes of ignoring her, should take care of this problem. Continue to play with her and handle her on a daily basis, but don't play games like tug of war or wrestling. As your puppy's strength grows, she is going to want to play-fight to see who's stronger. Even if you win, the message your puppy receives is that it's ok to fight with you. And that's not ok!
The Brat Stage, 4-6 Months
It is during this time your puppy will demonstrate even more independence and willfulness. You may see a decline in her urge to please you. Expect to see more testing-the-limits behaviors. She will be teething during this time and will looking for things to chew on to relieve the pain and pressure. She may try to assert his new "dominance" over human family members, especially children. Continue her training in obedience and basic behaviors but make sure to never let her off his leash during this time unless you're in a confined area. Many pups at this age will ignore a cue to come to their owners, which can be a dangerous, even fatal breakdown, in your dog's response to you. If you turn her loose in a public place and she bolts, the chances of injury or even death increase. She will also begin to go through the hormonal changes brought about by growing toward maturity. You may see signs of rebelliousness (think adolescent child). If you haven't already, you should have your dog fixed during this time.
The Young Stage, 6-18 Months
Sometime after your dog reaches 6 months, she will plunge headlong into adolescence – where hormones rule. Like people, dogs react differently to puberty. Some have an easier time of it than others, but a teenage dog of any breed can display unpredictable, even uncharacteristic behavior. It's not unusual to discover a puddle of urine, left by a formerly housebroken adolescent dog. Females use urine to attract mates; males use it to mark their territory. In adolescence, such tendencies may remain even though your dog is fixed.
The urge to chew also drives your teen-puppy's actions, and often is the first evidence that your dog is in adolescence. If you've let your crating rules lapse, you may arrive home one day to find significant damage done to a sofa, wooden furniture, or any chewable object. Around this time, your dog also goes through an intense period of shedding her puppy coat and acquiring the type of hair distinctive to her breed. Be prepared to brush him and vacuum your home often. The fact that your dog's skeleton and muscles are growing by leaps and bounds during her teen months can be a blessing for your relationship. You can't help but admire the enthusiasm and perseverance she applies in trying to coordinate gangly limbs.
Post-adolescence is a great time in your dog's life. She is young and exuberant but she's also learning all the things she needs to become a grown-up dog. Be realistic in your expectations of your dog at this time. Just because she's approaching her full physical growth and may look like an adult , she's not as seasoned and experienced as you might think. Gradually increase the scope of activities for your dog, as well as the training. Extend her activities to include more people and other animals. Allow her to interact with non-threatening, non-aggressive dogs.
Congratulations. You've survived the 7 stages of puppyhood and now you have a grown-up dog to enjoy for many years to come.