Foot
Introduction
Approximately 90% of all cases of lameness involve the feet and is an area that should always be thoroughly examined in any case of lameness.
A horse’s foot contains three bones, the pedal bone (third phalanx), the short pastern bone (second phalanx) and the navicular bone. The joint that forms between the pedal bone and the short pastern bone is the coffin joint, the navicular bone is positioned just behind this joint. The deep digital flexor tendon passes over the back of the navicular bone and attaches onto the pedal bone. The pedal bone is suspended in the foot by the laminae, sensitive laminae on the pedal bone connect with insensitive laminae within the hoof, which act like a kind of glue keeping the bone aligned to the hoof. The division between the sensitive and insensitive laminae can be seen as the white line. The hard hoof wall is produced at the coronary band and grows down, approximately 1cm a month. On the underside of the foot is the sole which can be variable in thickness, horses with thin soles can become lame very easily due to sore feet, and is usually concave so that only the edges at the hoof wall come in contact with the ground. The frog is the thick cushion on the sole of the foot. The structures of the foot.
Lameness involving the feet can be in just the one limb or more than one, especially common is lameness involving both front feet. This is very important in finding the cause of the lameness. Conditions such as poor foot balance, navicular syndrome, bruised thin soles and laminitis will usually involve both front feet causing the affected animal to be pottery at the trot or leaning back onto the hindlimbs at walk in severe cases of laminitis. In some cases, especially in navicular, the horse will be lame in one leg initially and then switch to a lameness in the other leg after a foot nerve block. Common causes of lameness involving one foot include foot abscesses, corns (bruising), fractures, nail bind and penetrating wounds.