Leave it alone, please
Self control is one of the most critical skills a dog needs to learn, and it is a skill that is required multiple times a day. Dogs are expected to refrain from picking up something forbidden when it appears within reach. Some examples that come to mind include: dropped medication, chicken bones, the hamster, dead birds, Granny's hearing aid, Susie's favorite stuffed toy, the last remaining baby soother...
Many people train "off" as a command with its associated threat: "Leave it or else." The trouble is, once the dog has swallowed the light bulb (I am not making this up), or the $3000 hearing aid, the ensuing "or else" does not do much to remedy the situation. It is not as if you can dock the dog's allowance or extract an IOU to pay for the costs of his transgression. Experienced clicker trainers, especially those whose training goals require an exceptional degree of reliability (those who work with guide dogs, service dogs, bomb detection dogs, etc.), know that training cues rather than commands produces a dog that can be counted on even in very difficult situations.
Cue vs. command
It is important to understand the difference between a cue and a command. A command implies a threat: "Do it or I will make you." A command is given before the behavior is learned, and it can be enforced if the dog does not comply. For example, a trainer may teach "sit" by pushing down on the dog's rump while saying sit, repeating the word and action over and over until the dog figures out that the word sit goes with the action of sitting, and that sitting fast enough will prevent the rump pushing. In the early stages of this kind of training, the dog associates the command "sit" with all kinds of stimuli and with actions that have nothing to do with the dog sitting on its own.
"Off" is commonly trained as a command by placing a temptation near the dog and holding him back, or tugging on his leash and saying "off" in a stern tone of voice. If the dog does manage to grab the prohibited item, the command is repeated while the item is forcibly removed from the dog's mouth. This method is stressful for the dog, and he may not learn much. In many cases, the command approach may place the trainer at risk of being bitten, too.
A cue is completely different from a command. There is no threat implied with a cue. A cue is like a green light that tells the dog that now is the time to execute a behavior for the chance of reinforcement.
A cue is attached to a specific behavior only after the dog is offering the behavior on his own. The "sit" cue, for example, is only given once the dog has learned to sit, and, therefore, the cue is not associated with anything other than the act of sitting. If the dog does not respond to a cue, a trainer knows that further training is required. The trainer does not assume that the dog is intentionally misbehaving and must be forced or helped to do the behavior.
Getting the behavior
A common and very reasonable question about teaching cues is, "How do you get the dog to sit or demonstrate the goal behavior in the first place, so that you can click/treat and eventually add a cue?"
There are many ways to get behavior without using any force or coercion. Using "sit" as the example, one of the easiest ways to get a dog to sit is simply to wait for it to happen! Capture the sit with a click followed by a treat. After two or three accidental sits followed by a click and treat, the dog will get the idea to offer a sit deliberately. Alternatively, a sit can be induced by holding a treat over a dog's nose and moving it back until he sits. A dog can also be taught to touch a target with his nose, and then the target can be used to induce a sit.
Regardless of the method used to get the dog to offer a sit, the cue is not added until the dog offers the sit without any prompts or lures. The cue should be associated with a freely offered sit, so that the dog associates the cue "sit" with the action of sitting, free from other stimuli. The clearer the association is between the cue and the action, the better the dog will learn the cue.
Steps to "off"
How do you get the dog to offer the "off" behavior so that you can click/treat and eventually add a cue? A popular method is to hold a treat in your closed fist and allow the dog to sniff, lick, paw it—whatever he wants to do to try to get the treat. Keep your fist closed until he backs off for just a fraction of a second, then click and open your hand to give him the treat. Alternatively, you can click when he backs off, and give him a better treat from your other hand. Avoid the temptation to say anything—no scolding or otherwise telling him not to pester your hand. The dog learns best if he figures it out for himself without fear of reprisal.
If the dog is too frantic to get at the treat, use something less tantalizing to start. If the dog loses interest and does not try to get the treat, use something more tantalizing.
Raise criteria gradually so that the click/treat comes only when the dog is deliberately moving his head back several inches from your hand. Raise criteria again so that the click/treat comes only when the dog makes eye contact with you after moving away from your hand. Gradually require longer periods of eye contact, until the dog backs off from your hand and maintains eye contact for three seconds. Now is the time to add the cue "off."
Show the dog your fist containing the treat. When he looks away from it and toward you, say "off," click, offer the treat, and say "take it." Teaching opposite cues in pairs like this is a really effective approach. From now on, always say "take it" when you give a treat after the dog responds to the "off" cue.
Practice with increasingly smelly treats. Add difficulty by holding your fist in different ways: out to the side, higher, lower, on the ground, on the table, etc. Once you have a reliable cue response (the dog looks at you right away and maintains eye contact when you hold out your fist and say "off"), it is time to increase the difficulty again.
Hold a low value treat in your fist so that just a little of it shows. Try giving the "off" cue. If the dog backs off and gives you eye contact, click and treat. If he licks at the treat, ignore him and repeat the steps described above. The dog may get some satisfaction from licking at the treat, but will give up eventually in favor of winning the chance to eat the whole thing (or the better treat from your other hand). Do not give the cue until the behavior is once again solid. When the dog will respond to the "off" cue with a little of the treat showing, increase the difficulty by using a tastier treat.
Practice in different locations with increasing levels of distraction until the dog responds to the "off" cue when you offer food partially exposed from your closed fist under any circumstances.
Making it harder
If you have reached this point, when you give the dog the "off" cue he will back off from your fist containing a partially exposed high value treat and give you three seconds of eye contact. The behavior is reliable even when you show him the fist placed in any position, and when you give the "off" cue in any location inside and outside of your house—no matter what is going on around him. You are ready to make it harder. The next steps should go quickly, since the dog now understands the "off" cue.
Hold a treat tightly between your thumb and forefinger. Ask your dog to sit. Show him the treat and give the cue "off" before he gets a chance to get up and come to investigate. If you do not think he is ready for this, separate yourself from him with a fence or baby gate so there is no chance of him snatching the treat. Give the cue "off" and click/treat when he looks at you. Gradually increase the duration of the eye contact until you are back up to three seconds. Increase the difficulty incrementally as before by using bigger and better treats, by holding the treat in different positions, and by training in difference locations.
It may be tempting to try offering a treat in your open hand or placing a treat on the floor to see if the dog will respond to the "off" cue, all the while ready to cover the treat if the dog tries to grab it. This is not a good idea, and you run the risk of having to start all over if the dog snatches the treat. You do not want to teach the dog that it is a race to get the treat and if he is fast enough he might (and probably will) win. Your goal is to have a dog that looks at you calmly, waiting for direction if temptation appears, and not a dog waiting with anticipation to race you to the treat. Your dog needs to be firmly convinced that if temptation comes along, the best way for him to win is to ignore temptation and to look at you for guidance.
"Off" with more valuable items—even your shoes!
Until now there has been no chance for the dog to anything more than (maybe) lick at the treat. By this point in the training he will have no interest in trying to go for the treat, since looking away from the food and at you has won him a click/treat every time.
It's time to move to training "off" with items that are on the floor or table, or otherwise more available to the dog. Start with a neutral item that your dog will not care about—a small box is a good example.
Let the dog sniff the box to see that it is of little interest. Ask the dog to sit. Place the box on the floor out of reach, give the "off" cue, and click/treat when the dog looks at you. Push the box closer and repeat. Increase the difficulty by repeating this process with objects of greater and greater interest to the dog. The more interesting the item, the further away from the dog it should be placed to start. Try putting a treat or toy in the box to make it more interesting, without giving the dog access to the treat or toy.
When you are ready to use the dog's favorite toys or your best leather shoes as training objects, guard against mistakes by putting the object under a clear plastic tub, on the other side of a baby gate, or out of reach with the dog on leash. Use a leash to prevent the dog from moving close enough to the temptation; the leash should not be used to tug or correct the dog. Ideally, the difficulty is increased for the dog in small enough increments that he will never bother to go to the end of the leash and the leash will remain loose at all times during this training. Be creative—come up with ways to prevent the dog from making mistakes and grabbing the item, while at the same time giving him the best chance to succeed in responding to your "off" cue.
Once you have progressed through an array of objects on the floor, table, and counter, and the dog will reliably respond to the "off" cue even with high value items, repeat the process using food. Start with the food at a distance and covered, and move toward uncovered food at close range, raising criteria in baby steps as before. By this time the dog will most likely have become conditioned and will intentionally ignore any temptation by looking away from it and toward you, even before you give the cue. Training will go very quickly at this point.
Do it your way
You may structure your training differently from what is described in this article, as these instructions and example are only meant as a guide. Keep in mind that the goal is to make it as easy as possible for the dog to get it right and win a click/treat.
Establish a very strong reinforcement history with the "off" cue. The more times you click/treat, the more reliable the behavior will become. At the same time, set things up so that the dog does not get a chance to snatch the treat and earn reinforcement for an undesirable behavior. Avoid situations where you need to race the dog to cover the food or use physical force to stop him from getting it. The best way to avoid these problems is to increase your criteria in baby steps, and to develop a strongly offered behavior or a strong response to the "off" cue before increasing the level of difficulty.
Some trainers add the cue early in the process and some wait until the dog shows the ability to back off from a high value treat in plain sight. This is a matter of personal preference and individual training style, and also depends on the personality of the dog. Some dogs do better with direction and some dogs do better if they figure it out on their own. If the dog shows signs of frustration—barking, lying down, scratching, yawning, or excessive lip licking—then you have made things too difficult. The dog cannot learn well when he is stressed and anxious. Reduce your criteria, make it easy for the dog to win a click/treat, end the session, and start your next session at a point where you know the dog can succeed.
Invest for the future
Teaching "off" with positive reinforcement may seem like a lengthy process, requiring more time and effort than simply giving the dog a good yank and yelling "off" at him. Certainly, careful step-by-step training without shortcuts is more time-consuming than any quick-fix method. Reliability comes with consistency, raising criteria in baby steps, and establishing a very deep reinforcement history.
Training with clicks and cues is fun for you and the dog, and helps build a strong bond of trust. Each cue that you teach lays a foundation for future training; the dog will learn each subsequent cue more quickly than the last. The time and effort you put into training "off" and other cues will pay off over and over. You'll enjoy life with a well-adjusted, reliable dog that looks to you for guidance when temptations appear.