Conformation in horses should be evaluated carefully, and all good judges, veterinarians, and horse owners should have a system to prevent missing any aspect. Each person has a system that works for him, so if you are curious, ask a respected individual in your area, or attend a judging clinic, writes Dr. Christina S. Cable in the October edition of The Horse
In brief, the horse should be viewed from each side, making sure to evaluate the horse at a standstill and while in motion (walk and trot). The fore and hind legs should be evaluated for straightness, correct angles, slope, muscling, and proportion. The pelvis and croup are evaluated for symmetry, length, and straightness. The head and neck are evaluated for normal balance and appropriate length and curvature, with special attention being paid to the teeth and bite.
To help you evaluate whether the horse's legs are straight, you can imagaine a plumb line (a piece of string with a weight at the bottom allowed to swing freely and hang straight). If standing in front or behind the horse, imagine the line from the point of the shoulder (front)/ tuber ischium (back) straight to the ground. The line should intersect the carpus (knee)/tarsus (hock), fetlock, pastern, and hoof in the middle of each structure. However, when viewing a horse from the side (profile), a line can be drawn from the top of the scapula/tuber ischium down the leg. In the hind leg, the line should follow the back of the hock and cannon bone to the ground. In the foreleg, the line should intersect the carpus and fetlock in the middle of the joints.