The first step in turning an adult dog into a reliable house pet is to embrace a key concept: There's no such thing as a "partially" house-trained dog. He either is or he isn't.

Bulldog looking guilty

Why is realizing this important? Because if you have a dog who is "sometimes" reliable, you have a dog who doesn't understand what's required of him, probably because no one taught him properly in the first place. Punishing your pet isn't fair, and it isn't the answer: You have to go back to square one and teach him properly. No shortcuts here.

Before you start training, though, you must be sure that what you have is really a behavior problem and not a physical problem. This is especially true with a dog who has been reliable in the past. You won't be able to train your pet if he's struggling with an illness. So check with your veterinarian first for a complete checkup.

If you've ruled out medical problems, house-training an adult dog uses the same principles as house-training a puppy, except you have to be even more diligent because you need to do some untraining, too. And a lot of cleaning: You must thoroughly clean any soiled area with enzymatic cleaner (available through pet-supply outlets) to eliminate the smell that invites repeat business.

You'll need to teach your dog what's right before you can correct him for what's wrong. To do this, spend a couple of weeks ensuring that he has nothing but successes by never giving him the opportunity to make a mistake.

Here's how:

  • Leash him to you in the house so you can monitor his every move during his training period. If he starts to mess, tell him "no," take him outside, and give him a command for going ("go now" or even "let's hurry"). Then praise him for doing right, so he starts to understand what you want.
  • Put him in a crate whenever he's not on leash with you. It's not unfair during training to leave him in a crate for four or five hours at a stretch — assuming, of course, that he's getting his regular daily exercise.
  • Take him outside first thing in the morning, as soon as you get home from work and just before you go to bed (when you put him in his crate for the night). Always remember to give your "go" command, and praise him when he does as you wish. People never seem shy about punishing their dogs, but too often forget to praise them — they take it for granted the dog should do the right thing. Never, ever forget the praise!

If you've been consistent, your dog likely will get a good idea of what's expected of him within a couple of weeks, and you can start to give him a little freedom. Don't let him have the run of the house yet. Keep his area small and let him earn the house, room by room, as he proves his understanding of the house rules.

Accidents happen. If you catch him in the act, tell him "no," take him outside, and give him the chance to set things right. Give your "go" command, and praise him if he does. Clean up the mess inside promptly and thoroughly, so he won't feel inclined to refresh his smell there. Don't punish him for any messes you find.

If you aren't catching him, you're not keeping close enough tabs on him. Go back to the crate and leash, and start over.

If you continue to have problems, ask your veterinarian for a referral to a veterinary behaviorist. One-on-one assistance can pinpoint the problems in your training regimen and get you both on the right track.