Halter your horse. With an assistant at the head of your horse, begin by observing your horse standing. Does your horse rest one foot, or keep a front foot placed forward (pointing)?

Next, have your assistant trot your horse directly away from you on a hard even surface. Is your horse trotting up normally or are they hesitant? Pay attention to how low your horse’s rear fetlocks settle with each step, and the movement of their hips. Is one side held higher than the other while bearing weight? Which one?

Your assistant should use pressure and instant release to ask a horse forward. As your horse steps forward, their head should be free of pressure and keep a billow of slack in the lead while trotting. Carefully study the movement of your horse's head and shoulders to help you identify the lame leg. In forelimb lameness, a horse's head raises as the lame leg hits the ground.

Then have your assistant trot your horse to the left. Does your horse hesitate or raise their head as the left foreleg is placed on the ground and bears weight? Does their fetlock sink fully with weight bearing?

Now have your assistant trot your horse back toward you. Does your horse raise their head when bearing weight on either of the front limbs? If so, which limb is on the ground as the head is raised? Are the front fetlocks settling equally in weight bearing? Perform this same exercise again, but have your assistant trot your horse to the right.

Now stand to the side of your horse and have your assistant trot your horse by you. Does each limb track the same? Does one hind limb track shorter than the other, i.e. is the length of each step the same? Now have your assistant lunge your horse both ways and perform the same evaluation.

Use the flattest, hardest surface you can when examining your horse for lameness at the walk. A concrete alleyway is ideal. Work in a well-lit area if possible. It is very helpful if you can send a video to your vet of the suspected lameness.

The lameness grading scale I use is similar to the AAEP's scale:

Grade 1: Barely noticeable, and only at times during the exam. Usually only noticeable on one of the turns.
Grade 2: More consistently noticeable and can see during both straights and one turn but not the other.
Grade 3: Consistently more noticeable both ways and both turns.
Grade 4: Difficulty walking but will put foot on the ground. Pronounced limp.
Grade 5: Non-weight bearing or toe-touching lame. Hops when affected limb is on the ground.

Note: When vets refer to a horse's limbs, we designate left and right by the horse's left and right, not yours.