For thousands of years, the ancestors of dogs hunted and scrounged for food. They would quickly seize and gobble whatever they could find, for fear of losing a tasty morsel to another animal.
Today's domesticated dogs rarely have to scavenge for their meals, but the instinct is still deeply ingrained. This often makes it difficult for dogs to keep themselves from snatching food off tables and countertops, and from young children. However there are a number of ways to dissuade your dog from engaging in this behavior.
How to stop a 4-legged food thief
First, ensure that your dog is well fed. Be sure to divide his daily allotment of food into 2 or 3 meals throughout the day. Dogs are less likely to be on the prowl for food if they aren't hungry. Consult with your veterinarian to see if you've been giving your dog enough food with the proper amount of nutrients to sustain him throughout the day.
Second, don't feed your dog people food. Dogs love to get scraps from the dinner table, but this can condition your pet to think people food is the preferred choice, and that they are entitled to it. This can also reinforce begging behavior. You should also avoid feeding your dog table scraps and other food not meant for them. This food may not be good for their digestive tract and may not have the nutrients they need. Worse, it could have ingredients—like chocolate—that can hurt them.
Try to keep food away from your dog. The temptation to steal food will be stronger if it is readily available. Keep your food well out of your dog's reach by placing it on high counters. And be sure to close off food storage areas. Another popular place for dog's to scrounge for food is in the garbage. So make sure your pet has no access to your household's trash cans.
Some dogs are very determined to get at your food, and may wait until you are not present before they make an attempt to snatch a bite. You can guard against this by setting up simple "shake cans"—sturdy plastic bottles containing a few pennies—that will fall and clatter if your dog tries to get at the food. (Make sure the bottle you choose can be securely and tightly sealed so that the pennies don't spill out.) The resulting noise should discourage your dog from future attempts, as well as alert you to the situation in order to deal with it in person.
Remember, you are competing against your dog's natural instincts, so in all cases, it's best to keep any scolding firm but gentle, and to reward your dog for displaying proper behavior.