There are two injuries which go under this name. One is merely a sprain of the back tendons, usually in a fore leg. It may be so slight as to escape notice till the horse be cool; or it may be such as to make him fall very lame in the middle of his work. Pressure on the part injured produces pain. The horse should walk slowly home.

The true breaking down is a rupture of the back tendons or of a ligament which assists them in supporting the fellock-joint. The rupture occurs suddenly, and generally when the horse is at full speed, or leaping down hill. The hind legs are not, so far as I know, liable to this accident, and i rarely occurs in both of the fore ones. The horse stops instantly, or he falls. On rising, it is seen that he stands on his fetlocks; they sink to the ground, the toe of the foot is turned up, and the sole looking forward. When only one leg suffers, the horse may possibly recover to do some kind of work, but he will hunt no more. He should be led slowly home. Sometimes only one branch of the ligament gives way. In that case the fetlock does not wholly come to the ground, and the horse may become as useful as ever. When both fetlocks come down the horse is ruined.