Why does a reining horse stop crooked?

A reining horse stops crooked for several reasons that can exist independently or in combination, and identifying the specific cause determines the correct response. The most common cause is drifting in the rundown — a horse that approaches the stop traveling left of straight will stop with its body angled left, and no correction applied at the moment of the stop will fix a problem that was established twenty strides before it. Straightness in the rundown must be confirmed before the stop itself can be straight. A one-sided physical weakness or stiffness causes many horses to drift consistently toward their weaker side in the rundown and to stop with their body angled in the same direction — lateral flexibility work and specific exercises that strengthen the weaker side address this over time. Leaning on the bridle or dropping a shoulder during the approach creates asymmetry that carries through to the stop: a horse that drops its left shoulder during the rundown will stop with that shoulder low, which pulls the slide to the left. Pain and soundness issues should always be evaluated before assuming a crooked stop is purely a training problem — a horse with hock soreness, a sore back, or asymmetrical hind end issues will stop away from the discomfort, producing a consistent crookedness that training pressure will not fix and may worsen. Rider imbalance contributes significantly as well: a rider who collapses their left hip, loads the right stirrup more heavily, or applies uneven rein pressure through the stop communicates a directional bias the horse responds to. Video of the rundown from directly behind the horse identifies whether the crookedness originates in the approach or the stop itself.