Penetration of the sole by sharp objects is a relatively common injury in the horse, however these injuries can have very serious consequences. The sole can be penetrated easily by a variety of foreign objects such as sharp flints, nails and wire.
The consequences of a solar penetration will very much depend upon where on the sole the injury has occurred and to what depth it has been penetrated. The bottom of the sole can be divided into two main areas: the ‘danger’ area which is found at the back of the foot centred on the frog and the ‘non-danger’ area, as shown in diagram 1. Superficial penetrations of both areas rarely cause any long term damage. Many of these wounds will subsequently develop in to a sub-solar abscess and will require draining. The sole is poulticed or hot-tubbed for approximately 3 days, and if there is no further drainage and the horse is sound the foot can be re-shod. Occasionally a sub-solar abscess will become “under-run” where the pus has tracked underneath the sole. These abscesses require more radical debridement but will heal without consequence over a period of time.
Deeper penetrations can cause more serious injuries. Deep penetrations in the ‘non-danger’ sole can result in the pedal bone becoming compromised. The bone can become infected (a condition known as pedal osteitis) or if the blow was powerful enough the pedal bone can become fractured. The principles for treating pedal osteitis are similar to those for sub-solar abscesses. The area of infected bone is identified with radiographs and examination of the penetrating tract. The infected bone is then debrided and the wound bandaged until the sole has re-grown to provide adequate protection. Pedal bone fractures heal remarkably well once the hoof has been stabilised with a bar shoe. The fracture must be immobilised for at least 8 weeks. A deep penetration within the ‘danger’ area can have very serious consequences. The central area towards the back of the horse’s foot is very complex and contains a variety of different structures.
Penetration of the navicular bone and deep flexor tendon can result in career threatening injuries. It is imperative that these injuries are identified as soon as possible so that treatment can begin immediately. The corner-stone of diagnosis is the radiograph. It is very important that if your horse treads on an object that is contained within the danger area it is NOT removed. Taking a radiograph whilst the object is in place will aid immeasurably with a diagnosis. Please see the radiograph below: Here you can clearly see a nail has penetrated the foot and has reached the navicular bone. No further diagnostics were required and this horse was sent immediately for emergency surgery. Due to the speed of the diagnosis the prognosis for a full recovery is excellent.