Ask your assistant to walk the horse away from you in a straight line and then back to you, repeat this in trot. Make sure that the leader allows the horse total freedom of movement in his head so that you can see how well he is moving. If the horse is lame in a hind leg then this should become obvious when the horse is being led away from you. This can be mainly noticed by the hip of the sore leg being held higher than the other, also the horse may appear to be nodding its head when the sore leg hits the ground. A horse lame in its front leg will be easily spotted when the horse is moving towards you, the horse will nod noticeably when the sound leg hits the ground.
Lameness is more obvious in trot and on a circle.
Another way of establishing lameness is by watching the horse as he moves around the stable or field, paying particular attention to whether he is moving less or more than usual or is over resting a particular leg. Now that you have worked out which leg is affected try to establish the exact location. If no obvious swelling or heat can be found, check the underside of the foot for bruising or injury particularly if the horse has been recently shod. If the horse is lame in both front legs it may be due to navicular, laminitis, ringbone or pedal osteitis. This helps to reduce swelling and clean wounds, remember to grease the heels before treatment.