Shoeing for heel pain

Shoeing for heel pain Lameness is a major cause of horses ending their athletic careers early. Pain in the palmar part of the foot (the heel region) accounts for up to a third of long term forelimb lameness in the horse. Advanced diagnostic imaging systems techniques such as MRI and nuclear scintigraphy have shown that a number of conditions can be responsible for palmar foot pain. One cause is thought to be pressure exerted on the navicular bone by the deep digital flexor tendon. This is made worse by the low heel conformation and broken hoof pastern axis seen in many horses with the condition. Therapeutic farriery is often used as part of the management of such cases. Shoes are applied with the aim of reducing the tension in the deep flexor tendon. Two specific types of shoe are commonly used: the egg bar shoe and the wedge shoe. The egg bar shoe moves the centre of weight-bearing back and so reduces the tension in deep digital flexor tendon. The wedge shoe is believed to reduce the tension in the deep digital flexor tendon.

But do they actually help? "What effect do the shoes have on the way the horse uses the foot?

Dr Chris Rogers of Massey University New Zealand, working with Dr Willem Back of the Utrecht University, conducted a study to assess how different shoes affected the pressure under the foot.

Healthy horses with normal foot conformation were used for the study. All feet were correctly trimmed and balanced before each shoe was applied. The researchers compared the effect of egg-bar shoes, 6° wedge shoe and plain shoes.

The pressures under the foot were measured using a pressure - sensitive plate set into a rubber walkway. It comprised an array of over 4000 pressure sensors, each about 0.39cm2. As a foot was set down on the plate and then lifted up again, the change in pressure at each of the sensors was recorded. By analysing the recordings, the researchers were able to build up a picture of the change in pressures under the shoe. They could also look at specific areas of interest -such as the heels, to measure changes in loading as a result of the different shoes.

Rogers and Back found that both shoes offered potential advantages for horses with palmar foot pain.

Compared with the plain shoe, the egg-bar shoe produced lower peak pressure at the heel and across the whole shoe. The 6° wedge shoe produced greater pressures at the outside heel, and hastened breakover (the time from the unloading of the heel to the unloading of the toe.)

However, as there are many causes of heel pain, a set therapeutic trimming and shoeing regime will not suit all cases. They recommend that the response be reviewed and changed as necessary.

Reproduced with kind permission of Mark Andrews.
© Copyright Mark Andrews  - Equine Science Update 2008

Added on: 01/05/08. Views: 300

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