It is generally easier to spot a lame horse in trot and some of the time horses only show up lame in trot, not walk. It depends where the pain is coming from and how bad.
To start with, a sound horse stands square with weight on all four legs perpendicular to the ground. Sometimes a horse will rest a backleg whilst standing, but resting a frontleg is not common at all.
A lame horse will often throw his head in time with his stride. If the pain is in a front leg, he will throw his head up as the sore side touches the ground. If the lameness is in a back leg, he will lean onto the sound side. Sometimes they drag the toe on the sore side. Imagine when you ahve hurt your leg, as you put the sore one down, you may flinch and not take as big a step as with the other.
If the pain is in just one leg, the horse won't move evenly. The severity can range from a barely noticeable hitch in the stride to a reluctance to put any weight on one foot. If a horse is lame onboth front legs or all 4 legs, the horse won't limp, jsut hold his head up very high and take short steps, possibly stumbing or hopping.
It takes a lot of practice, but soon you will be able to spot a lame horse a mile away. Well, not quite
