Leave it is such a practical command, with so many possible everyday applications, and is so easy to teach that there really is no excuse not to take a little time to do it right. It will take some time, and lots of repetition, for your dog to fully understand the command in all situations. If you want the command to be there when you need it, you have to work on it a lot so your dog doesn't even consider not turning his attention to you, even when what he has to leave is intensely interesting to him.

Meaning It

The command is not “Leave it, leave it, leave it, LEAVE IT!” or “Leave it?” The command is, simply, “Leave it.” Say it once, just loudly enough for your dog to hear you, but avoid shrieking, even if it's an emergency. When you need to use the command, it should sound the same way your dog has heard it hundreds of times before in training, albeit perhaps with more volume depending on the circumstances. For your dog to believe you mean it when you say “Leave it,” or that he has to, you must have a position of leadership with your dog, both so he will leave things that he wants, and so he trusts you not to let anything bad happen when you make him turn his attention away from something he thinks he's defending himself or you from.

Backing It Up

If you've done your part by giving your dog sufficient repetition in a wide variety of situations to really know the command, you may never need to correct your dog for ignoring a command (does the phrase “building on success” ring a bell?). If you haven't done enough training, or your dog was already obsessed with something before you started, particularly something dangerous, you may need to back up your command with an aversive. Depending on your dog and the danger level, you might use a shaker bottle, a squirt gun, water balloons, a remote collar, or whatever else works to stop your dog in his tracks.