Note: if you have a lame horse and do not know why, this is an excellent place to start.

Lameness is defined as "a deviation from the normal gait or posture due to pain or mechanical dysfunction". We recognize lameness because there is a change in the way our horse stands, walks, trots, or canters. Usually lameness is the result of pain, but not always. Mechanical factors and abnormal nerve function causes several well-defined problems with the horse's gait. The steps necessary to arrive at a firm diagnosis for the cause of a lameneess are:

1. Identifying a clear symptom of lameness.
2. Localizing those symptoms to the diseased leg or legs.
3. Localizing the area of the leg that is diseased.
4. Identifying the nature of the disease

Only when these steps are followed carefully is it possible to arrive at a correct diagnosis. Sometimes the steps are as easy as:

Steps 1 and 2: the horse will not bear weight on the right leg.

Step 3: The foot is as hot as a iron.

Step 4: Examination of the foot with hoof testers finds a sore spot that when pared into exudes puss.

But often the symptoms are such that they don't immediately lend themselves to identifying which leg is involved or even whether it is pain in the leg or foot responsible for the problem. This article takes each of the steps of diagnosing lameness and explains them so that you can recognize the changes associated with lameness, how to determine which leg is lame, how to localize the lameness in the leg, and then how identify the cause. Links to specific causes of lameness are then provided.

Before you can recognize abnormalities in a horses gait, you must develop a good eye for normal and there is no better way than to study healthy horses. Some gaits of the horse are naturally asymmetrical, the canter for instance where the right front leg and left front leg have entirely different flight paths. Many sound horses also walk asymmetrically. This asymmetry makes picking out lameness much harder. The best gaits to observe lameness are the symmetrical gaits like the trot or pace: in a normal horse the limbs on the right side have the same flight paths and landing characteristics as the limbs on the left. The advantage of a symmetrical gait is it allows you to compare the appearance of the left side to the right side so even small changes in the gait become easy to see.

As you watch a sound horse at a trot from the side concentrate on the poll and then the hip joint. If you have trouble locating the hip (coxofemoral articulation) get a diagram of the skeleton of the horse superimposed over the outline. You can put a piece of reflective tape over the hip joint to further get a good fix on this point. Watching the horse at the trot you soon realize these points move up and down but the vertical excursion is surprisingly small as the horse moves forward.

Sound Horse: The poll and the hip remain relatively level throughout the whole trotting gait cycle.

Front Limbs

Hind Limbs

Pain during weight bearing, even very mild pain that does not cause obvious changes in the way the leg moves, will change this symmetry.