Which structure is part of the stay apparatus and is susceptible to desmitis?

• A. Navicular bone
• B. Carpal bone
• C. Suspensory ligament
• D. Accessory carpal bone

Answer: (C)

The stay apparatus relies on ligaments to lock the limb in a partially extended position, allowing a horse to stand with minimal muscular effort. The suspensory ligament runs along the back of the cannon bone and attaches to the proximal sesamoid bones, transmitting tension to the tendons that cross the fetlock. This setup keeps the fetlock extended under weight, forming a key part of the stay apparatus that supports standing still or walking with less fatigue. Because the suspensory ligament bears a lot of repetitive load and strain, it is a common site for desmitis, an inflammatory condition that can compromise the stay apparatus and cause lameness. The other options are bones rather than ligaments, so they aren’t described as desmitis within the context of the stay apparatus.