How to do it:

Know your leads. Are you getting the correct lead – anytime, anywhere? Does your horse strike off on the lead you ask for, on whatever line you point him, not just on the rail?
Establish independent control of the hips and shoulders before tackling the counter canter. Turns on the forehand and haunches, shoulder–in and haunches-in are the phonics for building the language of counter canter.
Position your aids clearly. For the left lead I’ll position my left leg clearly at the girth, and my right leg behind the girth. I’m careful to make a distinction of at least six inches between these two cue locations, and accordingly, between the horse’s body parts I want to move. I’ll ask for slight flexion of the horse’s nose toward the lead – left lead, slight left flexion.
Keep your horse straight. Establish the outside lead on a straight line for a few strides before attempting your first “counter-turn”. We’re inclined to pull on the inside rein to steer the horse around a circle. Doing so at the counter canter allows the horse’s body to bulge off the track of the circle to the outside. The result? The horse trots to change leads. On the left counter lead, keep your horse’s body straight with a direct outside (left) rein and squeeze on the rein so your horse flexes head ever so slightly toward the lead. Direct your horse’s shoulders around the circle with your outside (left) leg at the girth. If necessary, an inside (right) opening rein helps to guide.
Think geometrically. Instead of a circle, I picture cantering the horse around an octagon shape, comprised of little mini turns. As the horse responds to each little turn cue, I relax my aids briefly to give him a “yes”. Initially, your horse is likely to be flustered being asked to lope around on the “wrong lead”. It’s beautiful how a well-timed release after every little turn reassures the horse he got the right answer. It’s my way of communicating “Yes, I really do want you on the wrong lead – you haven’t made a mistake.”
For example, traveling around the arena, begin a left lead counter canter a couple of meters from the track. This will help if your horse is inclined to assume, “I typically pick up the right lead when the fence is on my left”. Go straight for several strides, then open your right rein, keeping your left rein straight, and press with your left leg to angle the next stride slightly to the right. Release after that little turn and canter straight for another three or four strides before asking for another turn.
Start small. Don’t wait for a mistake. After just two or three successful little counter canter turns, walk and let your horse process.
When you feel any tension or any inclination to switch to the true lead, confirm the lead proactively before he breaks stride. You’ll sense confusion when your horse starts to get tense and hoppy, thinking about changing leads. Press in with your leg behind the girth. Pulse your rein, keeping his attention on task and asking for flexion toward the lead. Wait until he settles…and walk.
Remember – the best way to avoid unwanted responses is never to let them be expressed in the first place.

Counter canter was requested in an equitation class at a horse show last weekend. Some riders looked a bit tense. Others just blustered right into it – What have I got to lose?” Those who had done their homework struck off on the outside lead, and maintained that counter lead in a picture of calm and balance.

Why bother with counter canter? It may seem counterintuitive to practice the wrong lead. It’s certainly unnatural for your horse. For those of us who, in grade nine algebra class, asked “How will I ever use this in real life?”, we eventually saw, in the rear view mirror, that every fragment of learning pieces together to build more complex skills. Counter canter is one of those pieces.