As you've undoubtedly noticed, your dog has the ability to roll over when he wants to -- whether to scratch an elusive itch or to slather himself in smelly things right after you've given him a bath. But getting him to roll on command may be a whole different story. If you'll use reward-based training and follow the right steps, you can easily train your dog to roll over on command.
First, Some Basics
Make sure your dog knows the basics. Rolling over is a trick to teach only after your dog has learned basic commands. Since your dog will have to lie down before rolling over to do this trick, your dog will have to know how to sit and lie down on command. If your dog doesn't know how to sit and lie down, train these first, and make sure these behaviors are fluent enough before proceeding. Don't rush the basic training just to get to the tricks.
Finding the Right Location
Find the ideal setting to train your dog. Look for a quiet area where there are not many distractions going on. A quiet location will help your dog focus and learn at a faster rate. For training to roll over, you will also need plenty of room so he can move freely without interference. The surface should be relatively flat. A soft surface such as a grassy place or a carpeted spot will be more comfortable for the dog.
Using Powerful Rewards
Invest in high-value treats to facilitate training your dog to roll over. Rolling over will require him to lie down first, then you must entice him to roll onto his side and back. A tasty tidbit will help him make the right moves. If your dog appears to be not interested in treats, experiment with different treats until you find one your dog responds to -- some trainers resort to using hot-dog bits. If your dog adores toys, try a toy.
Putting Everything Together
Ask your dog to sit and lie down -- by now the dog should be doing these basic commands without treats. After the dog is in the lie down, introduce a treat between your index and thumb, allowing it to protrude a bit. Kneel by your dog and let him sniff the treat. Next, slowly move your hand in an arc from his nose toward his shoulder blades and then toward the floor on the opposite side. His nose should follow the treat, and so should his body. He will first roll onto his side, then on his back, and finally over to his other side. Once he completes the whole roll, immediately praise and give him the treat.
If your dog doesn't roll over on the first try, don't despair; rolling over takes practice. It helps to split the exercise in smaller parts. Reward your dog's baby steps if necessary, initially rewarding with the treat for turning his head, then for moving onto his side, then for moving onto his back and finally for rolling over to the other side. If at any times your dog seems to have difficulty completing a part of the rollover, take one or two steps back.
Fading the Lure
You don't want to have to present a treat every time you ask your dog to roll over. Begin to "fade" the lure by hiding the treat in your pocket, pronouncing the command and making the arcing hand movement. When your dog successfully rolls over, praise and give the treat from the pocket. Now, the treat is successfully being used as a reward instead of a lure.
Adding the Cue
Once your dog has started understanding the exercise, it's time to add the cue. Say "roll over" and then present the arcing hand movement. Continue praising and rewarding your dog every time he successfully rolls over. Repeat several times until your dog has started associating the action of rolling over with the spoken command. You can now start gradually fading the hand command by making it less and less noticeable so your dog responds to the verbal cue alone.
Moving to a Random Schedule
With your dog reliably rolling over upon verbal command, you can shift from a continuous schedule of reinforcement to a random schedule. This means you no longer give a treat every time your dog rolls over. By gradually reducing the frequency of giving treats you'll keep your dog on his toes, wondering when the next reward will come. This will also keep him performing even in the event you've run out of treats.