Most horse leads as a natural part of their stride, and many well-schooled race horses make this transition with little guidance from their jockeys. However, even when a horse knows how to do it (and it’s easy for them to do in practice), sometimes they simply will not change that lead. There are a few reasons why this can happen, and it usually has to do with the rider’s timing and balance.
The first step is to be able to feel which lead your horse is on, without looking down to check. Then you can help him to change his lead.
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To find which lead your horse is on you must compare the length of his strides: The front leg that hits the ground last, and then goes further forward between each stride, is his lead. This is the leg that should be leading when he is cantering in a circle to the right, for example.
The next step is to train your horse to recognize the correct lead by your voice and the pressure on his girth before you ask him for the canter. It may take some time to develop this connection. But it’s essential to a successful and safe canter transition. You can practice this on the longe line or in a round pen, and you should always praise the horse loudly when he responds correctly to your cues. This teaches him that picking up the correct lead rewards him and helps him to maintain his optimum balance.