Coming to the coronet, the examiner now tests the lateral cartilages with the object of determining if they possess their normal elasticity, or if they have become converted into "side-bones". Pressure should be applied to them from behind forward along their entire length, first while the foot is on the ground, and again after being lifted up and the weight removed from it.
Some horses' cartilages are naturally thick and resisting, while others are thin and yield to very slight pressure. In old horses they become hard with age without necessarily being ossified, and such cases call for considerable experience and judgment. Where, however, the existence of side-bone is established, unsoundness follows.