There are many reasons you should avoid punishing your dog or puppy if you find an "accident" in your house. It's fine to interrupt your dog if you catch him in the act—say "whoops" quickly and then rush him outside to finish the job (providing reinforcement for any outdoor pottying, of course). But, punishing after the fact is never a good idea. It will not help your dog be more successful in eliminating outside, and it can also backfire. When I meet with a client whose dog exhibits coprophagia (stool-eating behavior) and we delve deeper into the issue, I often discover that in the past the dog had learned that his owner finding "messes" is a VBT (Very Bad Thing) for dogs. These problem-solving and clever canines have learned to eat their own poop to save their frazzled owners from the stress of finding the mess! Now there are two problems—the dog is still not potty-trained, and there are difficult-to-find-and-clean olfactory cues that beckon the dog's nose and say, "Next time you have to go, go here!" For tips on house-training your dog, check out this article.