A keratoma is a type of benign tumour that grows inside the foot. It originates from the horn producing cells, usually underneath the coronet, and grows down the foot with the normal hoof.
When they reach the white line area at the toe, they cause separation of the bond between the hoof wall and sole. Once bacteria penetrate the foot, an abscess forms.
An underlying keratoma will always cause the abscess to recur.
The cause is unknown but can be associated with chronic irritation or trauma.