Counter canter is a naturally engaging exercise, which also increases straightness in the canter.
Counter canter aids are similar to the aids for half-pass (toward leading leg). When counter cantering to the right (horse is on the left lead turning right), the riders left leg stays at the girth and the right leg stays behind the girth, along with the riders right hip, to make sure the haunches stay wrapped around the left leg. Avoid over-bending the neck with the inner rein, or using so much outside leg that the quarters are pushed out of line towards the rail.
Two very good USDF Symposium video’s:
USDF 1993 National Symposium – Counter Canter and Lead Changes
USDF 1994 National Symposium – Exercises in Canter; including Half-Pass and Counter Canter
1. To strengthen for preparation of counter cantering: Use canter/walk transitions. This engages the horse, and allows the rider to get the horse more collected. Use Canter/walk transitions on a decreasing circle. Decrease the size of the circle and then make the transition. Keep the outside rein firm, the inside rein soft. The smaller the circle the softer the inside. Keep decreasing the size of the circle, smaller and smaller, and then ask for walk.
2. Shorten the canter strides for a few strides on the long side. Use the outside rein, keep the inside rein soft. The riders inside leg keeps the momentum with rhythmic presses. Shorten stride a few strides and then let the horse back out into working canter.
3. Shoulder fore in counter canter toward the leading leg. Have to come off the rail some to give the horse room to do the shoulder fore. Helps straightness, and helps to teach the horse acceptance of both reins.
Clinic With Lilo Fore – Gymnastic Exercises
Start with a 20-meter walk circle to the right at B; when you return to the track, pick up your canter on the right lead, and continue on the circle. Now do some transitions within the gait: a few strides of medium canter, then shorten the stride, then back to medium again. Hold the more collected canter a little longer than you think he can comfortably handle it (keep your reins quiet, say “steady,” and use a touch on his butt with your whip). In the medium canter, use frequent half-halts to encourage him to balance himself, instead of letting him use your hands for support, in the longer frame. When you return to the track at B, continue cantering on the right lead while you change direction through half of the arena and turn to the left. In the new direction, flex him toward the counter-lead; on the short side of the arena, turn left down the far quarter line (halfway between the center line and the rail). As you come down the quarter line in counter-canter, don’t so much think of the half-pass as let him think of it while you gradually go back to the rail on your right in counter-canter. (No need to push him sideways; the shape of the exercise and your leg aids will carry him. Just use a little less rein and you’ll go there.) When you get to the rail, walk, straighten him, pick up the left lead; then do the exercise in the other direction beginning with a big circle at E.
Developing the Canter through Counter Canter: