Hock problems in a horse can sometimes be resulting from pelvic instablity due to weak muscles in the pelvis allowing for increased flexion in the hock and shear forces. There may be a PI or AS Ilium as well as sacral and intertransverse problems. Do not forget about the pelvic stabiliing muscles. The Biceps Femoris, Gluteal, TFL,Adductor, and Sartorius may be contributing to the issue. It is alwa...ys a good idea to advise your owners on Pelvic Destabilizing Tech. featured in Activating your Horse's Core by Hillary Clayton. The one that is easy to do is as follows: Hold the forelimb off the ground but not too high, push back on the sternum or point of the shoulder on the same side and just enough to transfer the horse's weight backward but not off balance, hold for 5 sec. You are pushing toward the hind limb on the same side you have lifted. Repeat 3 to 4 times. Adjusting the subluxations as well as helping the horse become better stablized will improve performance as well as help the hock issue.
