How long does dog training last?

Well, there is no general rule here. Depends on what you want from the dog and when you start the training. If you begin with a puppy then it will probably take longer or at least until the puppy matures. The best part is we nurture it all the way into adulthood and never let bad traits develop so you have a joyful stable dog. Pay in mind though, you can train or re-establish a dogs behavior even at 10 years of age. There, of course, is the question of possible underlying psychological issues that need a special approach. These can take quite a while to properly rehabilitate and lots of work as well. Still, and I have to emphasize this, there is no such thing as a lost cause or a dog beyond approach. All you need is patience, determination and love in your heart.