I like to joke with my clients that my three dogs are over the age of 4, no more adolescents! Does this make a difference? Sure, but does it mean I am done training? Not even close!
Behavior will continue to improve if you continue working with your adolescent dog, but it will definitely get worse if you don’t. Both behavior and temperament will tend to stabilize, for better or worse, as your dog matures around his second birthday for small dogs, or third birthday for large dogs. But until then, if you don’t keep on top of things, there can be precipitous and scary changes in your dog’s temperament and manners. Even when your dog reaches maturity, you should always be on the alert for any unwanted behaviors or traits, which you must modify before they become hard-to-break habits.
Especially if your dog is a bit anxious or fearful of certain stimuli such as other dogs, kids, people, bikes, or UPS trucks. Creating positive association to these stimuli are a priority for many people with pups, but what if your dog hasn’t seen a child up close in months or years? Should you expect him to feel the same he did years ago? I would not leave it to chance! Many people are surprised by their adult dogs behavior, such as when they act shy, cower or bark at someone they use to have a positive relationship with. Remember, temperaments and behaviors are always changing. So, set your dog up for success and always help them feel safe and associate both new and old stimuli with a positive association. This is a never ending process; you never stop training!