The vet watches the horse trot in a straight line on hard ground (back and forth), then does the flexion again, but keeps each joint flexed for 1 minute. The horse will trot again immediately. If the gait is the same before and after the flexion, the test is negative, otherwise it is positive and reveals a problem with the tested joint or neighbouring structures. Then the horse is looked at in a circle, in both hands and at all three gaits, to detect any abnormalities in the kneecaps, muscles and tendons.