Which bone is rotated or sunk in founder?

• A. Coffin bone
• B. Navicular bone
• C. Sesamoid bone
• D. Cannon bone

Answer: (A)

Founder's effect centers on the coffin bone, the distal phalanx inside the hoof. In laminitis, inflammation weakens the laminae that suspend this bone from the hoof wall, so the coffin bone can rotate toward the sole or even sink lower within the hoof capsule. This rotation or sinking is the hallmark change in founder. The navicular bone sits behind the coffin bone and is more linked to navicular disease, not the rotation or sinking seen in founder. The sesamoid bones are at the fetlock joint, and the cannon bone is the long weight-bearing bone of the lower leg—neither is the bone that typically rotates or sinks in founder.