It’s appropriate to start thinking about developing increased collection in the canter in preparation for the pirouettes when the horse is fairly solid at third level. The horse must be able to collect the canter enough to be performing transitions between walk and canter and to perform a balanced ten-metre circle in canter. When a horse is at that point I will start thinking ahead toward my canter pirouettes, and I will begin developing the canter to a point where the horse is strong enough to carry the degree of collection needed for a canter pirouette.
The first exercise I use with a horse that is ready to begin increasing the collection in the canter is to ride walk-to-canter-to-walk transitions on a 15- or 20-metre circle. I use the circle because it’s much easier to keep the horse properly “through” on the circle than on a straight line. As I ride the transitions up and down, my goal is to maintain exactly the same balance in all the work. This means that the horse starts to step up into the canter instead of launching into it, and he is balanced enough that he can step into the walk, rather than fall into it. When the horse performs these perfectly-balanced transitions on the circle in both directions, only then will I ride them on straight lines.
When I am teaching this exercise to riders, I have found it very useful to demonstrate the exercise on foot. I walk a circle and pick up a “canter” with my legs, showing the riders that I can do that transition without going too much forward. I then take my canter back to the walk, showing again that I can step into it with no change of balance. It can also be useful for the rider to experience this on foot herself. I love this way of doing the exercise, because the rider gains an understanding of how important the balance is, either by imagining how it feels to perform it as I do on foot, or by feeling it directly by doing it herself (I will sometimes have a student try to do a canter pirouette on the ground herself in order to help her feel what balance is required, as well as the importance of how the horse has to sit on the outside hind leg).
The next exercise I like to use when teaching riders how to work the collection toward what would be a pirouette canter – and even preparation for the pirouette itself – is the following: on the straight line, I tell the rider to go into whatever degree of extra collection in the canter she is comfortable with. I then instruct her to look into the next corner and ride through that corner with as many canter strides as possible. The corner helps with the balance, and it also helps the rider avoid pulling back in order to increase the collection. I find this exercise is valuable because it helps riders learn how to maintain balance and control of the horse’s canter strides. In addition, a corner ridden very deeply with increased collection is essentially a quarter-pirouette.
What is important for riders to remember at all times when working towards the highly-collected canter and the pirouettes is that they should always take their time and stay calm. Once the rider becomes worried, the first things to be lost is the balance and the rhythm, at which point a good-quality pirouette is not possible.