One of the most frustrating things for any owner or rider is when their horse goes lame. Though it may seem obvious, diagnosis of lameness first requires identification of the lame limb. This can be more difficult than anticipated, especially if there is lameness in more than one leg or the lameness is subtle.
Diagnosing a lame leg is identifying the gait changes that occur when a horse reduces the load carried by the lame leg.
Identifying the lame leg
Lameness is most easily identified on a firm level surface. First the horse should be walked directly away from and then towards the observer for a distance of 15-20 metres. This distance is then repeated at the trot. The horse should be lead on a fairly loose rein to allow a free motion of the head, allowing the observer to note any head nod or other gait abnormalities.
It takes a great deal of practise and a trained eye to detect which leg is lame especially for subtle lameness, but there are some obvious signs which can be looked out for:
Forelimb lameness
- Watch for nodding of the horse's head. As the sound leg bears weight the head will nod down. As the lame leg bears weight the head will go up.
- With more severe lameness there may also be a shortening of the stride length of the lame leg. (Stride length is most easily observed from the side)
Hindlimb lameness
Hindlimb lameness is much harder to recognise than forelimb. A stiff limb flight, accompanied by dragging of the toe, a failure to track up or poor hindlimb impulsion can all be suggestive of a hind limb lameness.
- Look for an asymmetrical movement of the hips
- To reduce the load on the lame limb the whole pelvis is lifted upwards as the limb strikes the ground and then moves downward when the sound limb strikes the ground.
- It is often much easier to see the hip of the affected limb dropping as the sound limb hits the ground.
- This is often accompanied by a reduction in stride length on the affected limb.(Again most easy to see from the side)
More severe hindlimb lameness
- In more severe cases a horse will shift its weight forward when the lame limb hits the ground. As well as a dropping of the hip on the affected limb this also causes the head and neck to shift forward and nod down at the same time.
- Since the opposite forelimb bears weight at the same time as the lame hind limb during trot, this head nod thus mimics lameness in the forelimb.
- In other words more severe left hind lameness can mimic right fore lameness and right hind, left fore.
- Note: This head nod is not seen in mild to moderate hind limb lameness
Grading lameness
Lameness is graded on a scale of 0-10 (0 = sound / 10 = non-weight bearing) This makes it easier for vets to record any changes in the progression of a lameness and is particularly useful when trying to interpret a response to nerve blocks or for noting changes over time.
Other tips for diagnosing which leg is lame
- Lunging a horse on both reins can be very useful in exacerbating signs of lameness to determine the affected leg.
- Listen to the sound of the hooves as they hit the ground – a lame horse will bear less weight on the painful foot when it lands, so therefore it will sound quieter and the non-painful limb louder.
- Observe the horse moving from the side to look for variations in stride length between limbs.
- If a head nod is observed but it is difficult to correlate with a limb contacting the ground many vets will nod their own head in time with the horse’s, so that they can concentrate on watching limb flight and contact with the ground.
- If you are struggling to see which leg your horse is lame on feel free to ask your vet to explain what he or she is seeing whilst your horse is being examined.
Flexion tests
Flexion tests are useful in aiding a vet determine the location of pain causing lameness. This involves flexing a particular part of the limb to its full extent for a minute. The horse is then trotted up immediately after the leg is released. After flexion the grade of lameness can often be helpful in localising its cause. The opposite limb is flexed for comparison.
Once the correct limb has been identified, the source of pain causing the lameness must be identified. Firstly a vet will perform a thorough clinical exam of the limb to try to locate any areas of heat, swelling or pain. To confirm that a particular location is the cause of a lameness your vet may use nerve blocks.
Nerve Blocks
Nerve blocks involve infusing a small volume of local anaesthetic into the nerves in a horse’s leg to desensitise the area innervated below the injection site. This means that a nerve block high up the limb blocks off much more of the limb than a block by the heels.
See article on Nerve Blocks for further details
As with any condition the sooner it can be identified the greater the chance of a positive response to treatment. If you are at all worried that your horse may be lame it is advisable to contact your vet immediately to identify the source of the problem.
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