Supplements for his joints and slow and easy. Apparently strengthening the muscles required for dressage is GREAT for older horses, as it makes it so they can move properly and supported by all of their muscle groups, easing the demand on the joints. Go for it!
Yes, but when they are over 18 they can't show in the FEI CDI shows make sure to bring him back up slowly and put him on some supplements to help his joints.
yessssssss you have toooooooo!!!