Answer: This horse suffered from severe pastern arthritis (ringbone). After careful deliberation, the decision was made to fuse the joint surgically with a plate and screws. We can see the SVEC surgical team placing the hardware in this video (x-rays are in the comments). He will stay in a cast for 2 weeks post op and is expected to make a full recovery.
We have had good success with this procedure under the right circumstances for pasture soundness, as well as going on to their previous level of competition!