History

Most horses will have a known history – the owner or handler may have noticed the moment of penetration or found a foreign object embedded when picking out or examining a hoof. The foreign body may be left in place by an owner if there is no risk of the object penetrating deeper if the horse bears weight. In other cases, the penetrating object will have been removed; if this is the case, the person who removed it will ideally have marked the site of penetration on the hoof capsule (a hoof knife leaves a more permanent mark than even a permanent felt pen!) and will have made a note of the depth and direction of penetration.

Inspection

Normally, the diagnosis is relatively easy to make thanks to the history and obvious findings; the foreign body is often visible, totally or partially embedded in the hoof capsule. If the foreign body has already worked loose, a trace of blood on the hoof can be an indicator of a foreign body penetration. In this case, it is prudent to check the horse’s surroundings to see whether any objects lying around can give some indication of the nature of the object that has penetrated the hoof (nails, screws, etc).

Palpation

Care is needed when locating and exposing a foreign body that has become embedded into the underside of the hoof. Since any manipulation of the affected area is extremely painful, examination with the hoof testers can elicit hefty pain reactions.

Exposing the puncture wound

Regional anaesthesia (nerve blocks)

In many cases, regional anaesthesia is indicated to prevent pain reactions by the horse when removing the foreign body or exposing the puncture channel. In any case, the affected region will need to be anaesthetised with an abaxial sesamoid nerve block before the puncture channel is probed up to the sensitive dermis.

Irrigation and probing

Needle aspiration of the synovial structures

Radiography