A joint is the hinge between 2 bones. In between is a layer of viscous synovial fluid that lubricates and protects the cartilage at the end of the bone. The muscles, tendons and ligaments around the joint absorb shocks and keep it safely in place. If your horse is doing intense work, the joints will endure a lot of friction from the bones because the quality of the synovial fluid decreases.

Overuse, age, injuries and infections cause inflammatory reactions. If your horse has recurring inflammations, the composition of the synovial fluid changes, becoming thinner and losing its ability to properly cushion shocks.

This makes the articulated movement of the joints less supple and increases the risk of serious injury. Over time, joint problems will get worse. Large impacts damage the cartilage beyond repair. That damage then spreads to other parts of the body, such as the muscles and ligaments, and can eventually lead to lameness.