"Come here. Sit. Lie down. Stay." How many of those cues can your recognize? Even more important, how many of those actions will your dog perform on command?

Or what about not jumping up on everyone who comes through the front door? It may have been cute when your dog was a puppy, but now she's 50 pounds of canine energy that can knock Aunt Margaret clean off her feet. What can you do to stop unwanted behaviors? Is it too late for your dog to learn new tricks? Three experts explain everything you need to know about training your dog at every stage of life.

How Soon Can You Start Training Your Dog?

"One thing a lot of people don't realize, " says Gail Fisher, author of The Thinking Dog, "is that if a dog is awake, the dog is learning."

Recognized as one of the world's top lecturers on dog behavior and training, Fisher says there is no reason not to start training your puppy the day you take it home. "As a breeder, I was able to start training puppies as young as 4 and a half to 5 weeks old. So, if they can learn that early, you can certainly start training when the puppy is 8, 9, or 11 weeks."

Fisher, who owns All Dogs Gym and Inn in Manchester, N.H., adds that a puppy will actually be learning whether you train it or not. "If people give in to a dog that is pestering them, the dog has learned to pester people."

Can a Dog Be Too Old to Be Trained?

"Any dog can be trained if it is sufficiently motivated and if the trainer has the skills, knowledge, and patience, " says Don Hanson, the chair of the Association of Dog Trainers.

Hanson says that there is one exception to the idea that any dog can be trained. "I have two 14-year-old dogs. One has what's known as cognitive dysfunction or, less formally, doggie dementia. There's probably not a whole lot I can train her to do at this point."

As long as the dog is physically able to learn, the training techniques are generally the same for any age dog. "The difference is the older a dog gets, the more untraining you may have to do, " Hanson says. Because dogs are always learning, they may pick up undesirable behaviors. To make changes in a dog's behavior, unlearning must be part of the process.

"Unfortunately, " he says, "the vast majority of the people we see wait until their dog is 6 months to 2 years old before they start to train it. That makes the job a lot harder, and many people don't have the patience to stay with it." But with patience and consistency, it's not an impossible task.