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Dogs learn best through positive reinforcement and they quickly learn the best way to get it. Every time your dog is able to go to the bathroom in his designated spot, reward him with a little treat, lots of praise, and a scratch on the head. You can, of course, reward your dog for other things, like learning how to sit and stay. All good behavior should be rewarded. When you're treating your dog for going to the bathroom in his spot, give him a treat and praise right after he finishes relieving himself. Don't give it too early or too late, or he won't associate it with going to the bathroom in the right spot. Some people have had success using the bell method instead of a treat. When your dog goes to the bathroom in his spot, you ring a bell or pleasant-sounding chime as part of his reward. The dog will come to look forward to the sound of the chime, which should only be used in this specific situation. The drawback here is that, eventually, you won't want to keep using a chime or bell every time your dog goes to the bathroom. Initially phasing it out might be confusing to the dog. Whenever you're taking your dog to the bathroom or talking about it, keep your voice light and pleasant. Never raise your voice or take on a menacing tone, because your dog will start to associate his bodily functions with punishment and fear. If your dog makes a mess inside, you can withhold praise, but don't yell at the dog or make him feel ashamed. If using verbal cues, such as "outside", "go potty", or "good dog" be consistent. The repetition of these words along with the action and environment will reinforce where you want your dog to relieve himself. Dogs don't respond well to punishment. It scares them and instead of learning to perform well for you, they learn to fear you. Never yell, hit, or do anything that could cause your dog to feel afraid. Do not rub your dog's face in his mess. Contrary to some beliefs, this does not teach a dog not to go to the bathroom in the house. The dog will not understand what you're doing and you'll just end up scaring him.
Give your dog treats and praise each time he successfully goes outside. Time the reward correctly. Consider using a bell or chime to aid in training. Keep your voice and manner light and friendly. Never punish the dog for making a mess.