A 12-year-old Warmblood sport horse presents with subtle, intermittent right forelimb lameness that worsens on soft footing and improves on firm ground. Flexion tests are negative. Diagnostic analgesia of the distal limb fails to improve the lameness. MRI reveals focal cartilage erosion on the palmar aspect of the lateral trochlear ridge of the distal radius. Which condition does this BEST describe?

Remaining questions and full explanations are VIP-exclusive.