Any type of open sore or drainage from around the cornet band is a sign of infection within the hoof. These may include white line disease, quitters, and gravels. Of these gravels are the most common and least destructive. A gravel is the result of a puncture wound to the white line. The white line refers to an area between the hoof wall and the laminae. All foot wounds are predisposed to infection, and since the infection can not travel down through the sole of the foot, it travels upwards through the cornet band. Most infections and abscesses will "blow out" at the cornet band.
White line disease is more serious because the condition is often not discovered until the infection is quite progressed. It is also known as seedy toe. The infection is caused by a bacteria, yeast or fungus at the ground level and works its way up the white line to the coronary band. The disintegration of this white line creates a hollow space between the hoof wall and the sole. The hollow space becomes mealy or "seedy" and fills with cheesy material and debris. The loss of the supporting white line against the pull of the flexor tendon can cause rotation of the coffin bone, at which point the condition would be considered an unsoundness. The only way to treat the condition is to remove all of the affected area. This often requires removal of so much of the hoof that prosthetic hoof repair material and special shoes must be used to preserve the foot. It is believed that horses that have suffered white line will be predisposed to contract it again.
A quitter is a deep seated infection of the cartilages around the coffin bone. The inflammation will eventually blow out the cornet band. Injuries to the sole of the foot often lead to this infection. The only treatment is to surgically remove the affected cartilage. Many horses have a complete recovery, but if the surrounding structures have been damaged there may be permanent lameness.
The last unsoundness you should look for in the hoof area is ringbone. Ringbone is more accurately a condition of the pastern, but because its effects can often be seen at the very top of the hoof on the cornet band I have included it here. Ringbone is a type of arthritis of the pastern joints. Low ringbone affects the joint where the coffin bone meets the short pastern bone. High ringbone affects the joint where the short and long pastern bones meet. Ringbone will look like a hard lump on the cornet band.
