Which self-limiting disease of long bones affects large breeds aged 5 to 18 months and causes shifting leg lameness?

• A. Osteochondrosis (OC)
• B. Osteochondritis Dessicans (OCD)
• C. Hip Dysplasia
• D. Eosinophilic Panosteitis (Pano)

Answer: (D)

Eosinophilic panosteitis is a self-limiting inflammatory process of the medullary cavity in the long bones of growing large-breed dogs. The classic presentation is a puppy aged around 5 to 18 months with shifting leg lameness, meaning one leg is painful one week and another leg the next. The pain comes from the bone itself, not the joints, so lameness can move between limbs as different bones become tender. Radiographs often show increased density or patchy sclerosis within the medullary canal of affected long bones, such as the humerus, radius/ulna, tibia, or femur. The course is typically self-limiting, with improvement over weeks to a few months with rest and supportive care like NSAIDs if needed.

This description fits best because it combines the age and breed pattern, the long-bone location, migratory lameness driven by bone pain, and the spontaneous resolution that characterizes panosteitis. Osteochondrosis/Osteochondritis dissecans involve joint surfaces and often show focal joint changes rather than medullary bone changes and aren’t typically self-limiting. Hip dysplasia centers on the hip joint with a different gait pattern and radiographic findings.