Neck reining is the Western riding system of steering in which the horse responds to the rein pressing against its neck rather than to direct rein pressure on its mouth — moving right when the left rein presses against the left side of its neck, and left when the right rein presses against the right side. It allows the rider to hold both reins in one hand and steer without directing the horse through bit contact, which frees the other hand for working cattle, roping, or any other task that requires one-handed riding.
Training a horse to neck rein begins when the horse already steers reliably from direct reins. The neck rein is introduced by applying it a fraction of a second before the direct rein that the horse already understands — right neck rein pressure followed immediately by right direct rein if the horse does not respond to the neck rein alone. Over many repetitions, the horse learns to anticipate the direct rein cue after the neck rein and begins responding to the neck rein before the direct rein is needed.
The transition from direct rein steering to neck rein steering typically takes several months of consistent work, with the rider gradually reducing the direct rein component as the horse's neck rein response becomes more established. The common mistake is eliminating the direct rein backup too soon — before the neck rein response is truly confirmed — which produces a horse that steers poorly because neither system is fully established.
Al Dunning's approach to neck rein training specifically addresses the timing of the transition and the importance of maintaining the direct rein as a backup until the neck rein is established at all gaits, in both directions, and in various environments. A horse that only neck reins reliably in the arena at home but reverts to ignoring the neck rein in new environments or when excited has not fully learned the neck rein — it has learned to neck rein under specific familiar conditions.