My horse is stiff to the right what can I do about that?

One-sidedness in horses is completely normal and nearly universal — just as people are right or left handed, horses have a naturally more supple side and a naturally stiffer side, and for the majority of horses the stiff side is the right. What varies is the degree of asymmetry and how much it affects the horse's work. A mild preference for bending left is something you manage and improve gradually over time. A horse that is dramatically stiffer to the right than the left, particularly if that stiffness appeared suddenly or has gotten noticeably worse, warrants a veterinary evaluation before you interpret it purely as a training issue. Chiropractic problems, muscle soreness, ulcers, and dental issues on the right side of the mouth can all present as apparent stiffness to the right, and training through a physical problem is both ineffective and unfair to the horse. Once physical causes have been ruled out, the approach to right-side stiffness is systematic and patient. The core problem is that the horse's right side — his jaw, neck, ribcage, and hindquarters — is not as supple and yielding as his left, and the solution is progressive gymnastic work that develops that suppleness gradually rather than forcing it. Forcing a stiff horse to bend before the muscles are ready creates resistance, tension, and a horse that braces even harder against the direction he finds difficult. Start with simple lateral flexion at a standstill. From the ground or the saddle, ask the horse to bend his neck to the right with a soft, steady rein and wait for him to give — to release the tension in his neck and jaw and flex softly toward the pressure. Do not pull the head around forcefully. Just maintain a quiet, consistent contact and reward the slightest try with an immediate release. Do this daily, both directions, until the right side begins to approach the ease and suppleness of the left. Under saddle, circles and serpentines to the right at the walk and trot are your primary tools. Ride the right circle with your right leg active at the girth pushing the horse's ribcage out and away, your right rein guiding the bend, and your left rein controlling the pace and degree of bend. Leg yields moving right, spiral circles, and frequent direction changes that require the horse to switch his bend all contribute to developing the symmetry you are after. Progress will feel uneven — some days the right side will feel almost as good as the left, other days it will feel locked up again. Stay consistent, keep the sessions constructive rather than combative, and over months of correct work the difference between sides will diminish to the point where it no longer meaningfully affects the horse's performance or comfort.