Hoof cracks in the wall of the horse’s foot can range from being little more than a cosmetic blemish to a serious cause of lameness and pain. They can run vertically or horizontally, when they appear parallel to the coronary band.
A vertical crack that begins at the coronary band is called a sand crack, whereas one that appears to originate from bottom of the hoof wall is known as a grass crack.
To understand the significance of hoof cracks, it helps to know how the hoof wall grows and the way it is structured.
The hoof wall
The hoof wall grows downwards from the coronary band, originating from “germinative epithelial” cells at the coronet. It takes between 10 and 12 months for new hoof wall to grow from the coronary band to where the sole meets the ground (the “solar surface”). At the heel, the process takes around three months.