Signalment & History
A 14 month old MI mixed large breed dog presents with left thoracic limb lameness. On physical examination, there is pain in his left shoulder.
Findings
There is a focal lucency in the subchondral bone in the caudal humeral head associated with subchondral bone sclerosis and flattening of the humeral head.
Diagnosis
Osteochondrosis is a common cause of lameness in young, rapidly-growing, large and giant breed dogs. Osteochondrosis is a cartilage defect caused by failure of endochondral ossification. Radiographic signs include focal lucencies on the joint surface and subchondral bone sclerosis deep to the lesion.
- Osteochondritis dessicans is a form of osteochondrosis that occurs when the cartilage defect detaches and creates a cartilage flap.
- If this flap mineralizes, it may be visible on radiographs.
- Osteochondrosis is characterized by defective endochondral ossification leading to thickening of the articular cartilage. Subsequently, nutrient diffusion from the synovial fluid is insufficient to meet the metabolic demands of the deep cartilage layers and cartilage degeneration and necrosis results. Fissures form in the articular cartilage. If the fissure forms a fragment that breaks off from the surrounding cartilage, the disease is called osteochondritis dissecans.
- Osteochondrosis occurs in young, rapidly growing, large breed dogs
- Clinical signs usually occur at 6-9 mo
- Males are predisposed
- Often bilateral
- Can occur at multiple sites in one patient
- Osteochondrosis occurs at specific anatomical locations, including the:
- Medial and lateral trochlea ridges of the talus
- Trochlea of the femur
- Lateral and medial femoral condyles
- Distomedial aspect of the humeral trochlea
- Caudal aspect of the proximal humeral head
References
(Baines, E.) Clinically significant developmental radiological changes in the skeletally immature dog: 2. Joints. In Practice (2006); 28(5), 247-54
(Olson, S. E.) General and aetiologic factors in canine osteochondrosis. Veterinary Quarterly (1987); 9(3), 268-278
(Thrall, D.) Textbook of Veterinary Diagnostic Radiology (6th Ed) p 267
