EVERYONE involved with horses will be familiar with the old adage – ‘no foot, no horse’. The most common lameness in all horses, regardless of whether you are dealing with a finely tuned racehorse or a Shetland pony, is a foot abscess. Foot abscesses are caused by a localised bacterial infection in the sensitive structures of the hoof. Pus is produced by the body in response to fighting this infection.

The pus accumulates in the hoof wall and, as the hoof cannot expand, the increased pressure within this pocket of purulent material causes significant pain, resulting in lameness.

Bacteria can gain entry to the hoof wall in a number of different ways. The most common route of entry is through a break or defect in the junction between the sole and the hoof wall which is known as the white line. Bacteria may also gain entry through a puncture wound in the sole or by way of a full thickness hoof wall crack or old nail holes.

Horses with foot abscesses will generally present with a sudden and severe lameness.

Quite often they will walk on their toe and be reluctant to put their foot level on the ground. Examination of the leg will reveal increased pulses to the foot and heat in the hoof wall when compared to the hoof on the opposite leg. There may also be swelling in the pastern and fetlock region on the affected leg.

Once a foot abscess is the suspected cause of lameness the foot is examined with hoof testers. These are designed to apply pressure at specific points on the sole and white line. The horse will resent direct pressure applied to the point of origin and in doing so allows you to locate the abscess.

Once the origin of the abscess has been located, the shoe is removed and the foot cleaned.

Sometimes it is possible to see a black tract in the white line and using a small loop knife, you can follow this line to locate the infected area. A small hole is made to allow for drainage and provide relief of the pressurised pus. Once the abscess is draining and so reducing the pressure within the hoof wall, the horse will experience some immediate relief.

In some cases the abscess will not be visible and cutting too much hoof or going too deep with the knife will be detrimental.

The abscess will always take the path of least resistance to drain and many deep-seated abscesses will work up the hoof wall, bursting at the coronet band rather than draining through the white line.

Regardless of whether an abscess is located and draining or if it is deep-seated, the foot must be kept clean and a poultice applied. A poultice is designed to soften the foot and raise the temperature of a localised area of foot, and in doing so, help the abscess drain out. Often, standing the horse in a solution of Epsom Salts will have a beneficial effect in draining the abscess.

FOOT CARE

Foot abscesses are a common cause of lameness among all horses but there are measures which can be taken to minimise the risk of their occurrence. Prevention is mainly achieved through proper foot care which is focused on promoting a strong, solid junction between the sole and the hoof wall that resists penetration by debris. Foot abscesses are less likely to occur when a solid white line is maintained.

Care should be taken to avoid excessive toe length as this increases the bending force exerted on the toe, leading to a widening and weakening of the white line. Distortion of the hoof capsule can also cause a break or weakness in the white line which will predispose to the formation of foot abscesses.

Exposure to excess moisture will also increase the risk of foot abscess formation as it softens the foot, weakening the junction between the hoof wall and sole and allowing entry of debris.

Thankfully, in the majority of cases foot abscesses can be dealt with quickly and efficiently once identified and usually result in a quick return to the normal training regime.

John Martin from Stradbally, Co Laois, who graduated from University College Dublin and is in practice at Mark Johnston Racing.

This article first appeared in the Kinssley Klarion, published by Mark Johnston Racing.