Every pet owner has at least one story to tell about the new puppy that "stole" the ham sandwich from off the picnic table, or stole his owner's car keys and hid them in its bed.
These stories are amusing, even endearing; but, the problem can be annoying and the behavior should be stopped.
First though, a clarification of terms.
Dogs do not steal.
They can't, they don't understand the principles of ownership.
They only understand the concept of possession.
If something is available, and they want it, they'll take it unless they have been trained not to.
It's fairly easy to understand why dogs take food that hasn't been given to them - it's food! Dogs can be conditioned to expect a dependable meal once or twice a day, and will look forward to it.
But the concept of regular scheduled meals is a human creation based upon the expectation that food is always available.
Dogs, in fact all animals, will eat whenever they are hungry and food is available.
The most straightforward way to stop a dog from taking food that isn't offered is to keep all food out of reach.
A dog can be trained that certain places are not available to him.
He can be trained to understand that the kitchen table, dining room table, and outdoor picnic table is off limits for any reason; that front paws on the table are not acceptable behavior.
When he is so trained, food placed on these tables while you are around should be perfectly safe from being purloined.
I wouldn't recommend that you leave a ham sandwich on any of those tables, however, when you are away for the day.
It would be an excellent test of the dog's training, but would nonetheless be torture.
Dogs want to take food that is appealing.
Never feed your dog from the table at which you are eating.
This simply reinforces the dog's connection with the table as an acceptable food source, and turns him into a beggar.
If you wish to share some food from the table, remove it from the table and offer it to the dog in the dog's traditional eating area or utensils.
Determining why your dog takes your personal property requires more investigation to find a reason.
Often, when the dog takes something while you are watching and taunts you with it, the dog simply wants to play and is using your readily available property as a toy.
This is common behavior for dogs that have learned to play games like "tug-of-war" with an old sock.
From the puppy stage, your dog should be trained to expect that such games will be played only when using the dog's own toys, and suitable toys should be provided to allow for these different games.
If an owner succumbs to the temptation of playing tug of war with a kitchen towel, the dog will learn that he can play that game with anything that the owner happens to be holding.
Again, as with food, any items that are at risk of damage or could injure the dog should be kept out of the dog's reach.
When the dog is caught taking items, such as shoes, slippers or other clothing normally stored on the floor, give the dog a sharp "no" command, and then heap praise and petting on the dog for dropping the item.
Occasionally dogs will chew on available items when home alone or bored.
When a dog is provided with suitable toys that he has been praised for using, he will defer to those toys for play rather than taking your personal property.