The aid for canter is given with the inside leg (left leg) at the time of the left hind toe-down (begins stance phase for that leg) supported by the outside rein. This is a diagonal aid for the transition. Hands have the function only to complete the connection through the horse so the aid can be answered in balance.

Preparation for a transition can be a half-halt. Half-halts can be strong or subtle but should be a clear, tactful request for the horse to understand rebalancing or adjusting for "what comes next." I prefer a half-halt with a combined stretch of upper body (avoids driving with the seat and "extra noise" from rein to bit) combined with a soft, definite touch of the calf that will ask for the transition itself. Thus there is a "library" of half-halts that go with dressage movements. Some riders will include a positioning of the poll or hindquarters with the half-halt. I prefer to separate the two and adjust the horse's spine prior to the half-halt. Whatever the choices, horse and rider should practice together until there is confident understanding of this communication by touch.

I am riding bareback in order that a saddle and pad do not hide the horse's shoulder and back muscles. In Frame 4 above, Max is showing a positively dissassociated left canter diagonal where the hind leg of the pair (LH-RF) lands fractionally before the right front leg. This reflects the lowered hindquarters of this collected canter, which converts to the canter of pirouettes.