Difficulty: Hard
This very well may be one of the hardest tricks to teach your dog, and is one many movie dogs learn and act out on the silver screen. Next to Jump Rope and Bang, it doesn't get much harder than this. Although teaching this trick can be frustrating at times, it is a momentous achievement once your dog learns it, and can bring joy and laughter to you and your family; not to mention guests and friends.
Step 1: Hook up your dog's leash to his collar and use it to pull his front dominant paw up - be very careful as you walk with him - click and treat when he walks one or two steps.
Step 2: Keep doing this until he is successfully 'Limping' with the help of the leash.
Step 3: Try to encourage your dog to put less weight on his lifted paw. Over time use less and less force on the leash, and he will be able to limp on his own.
OUR EXPERIENCE
Teaching Caspian to limp was very frustrating at times. It took a lot of work, many training sessions, a whole bag full of treats, and many many hours. But it was well worth it. After teaching your dog this trick you can combine it with Crawl and Play Dead to give your guests a thrilling death scene (See Trick #52—Bang).
I started out by attaching his leash to his collar, and using it to support his paw, keeping it in the air. Then I held my clicker away, motioning him to walk to it. I clicked and treated as soon as he made a couple of steps forward. The downside to supporting his paw in this way, is that it may condition him to put more weight on that paw; the opposite of what you want. There are other methods you can try, such as putting a sock on the paw: usually dogs will try and raise that paw, feeling the unbalance. Whichever method you use, be consistent, but don't feel like you can't try new things if your dog just isn't getting it. When teaching this trick, keep in mind that teaching your dog to limp on command is one of the hardest things to do, so be patient, be consistent, and vary the reward.
TEACHING TROUBLE
He won't transition into lifting his paw on his own!
It may take a long time for your dog to understand what he needs to do. It takes a long time of determined work to get this trick, even if you have a smart dog. Keep working with him until he gets it right!
Tip: "Be patient! This trick can take months to perfect; don't rush it. Dogs learning this trick need several breaks because of the stress you're putting on his mind and body."