Degenerative Joint Disease

(DJD)

DJD in a horse (Image sourced from Bristol Biomed Image Archive with permission)

Osteoarthritis, osteoarthrosis
Due to acceleration of normal ageing process - wear and tear
Destructive disease leading to:
- Loss of weight-bearing articular cartilage
- Erosion, fibrillation of cartilage
  - Clefts in the cartilage, perpendicular to the surface
- Complete exposure of underlying bone
  - Bone appears polishes, dense - eburnation
  - Radiographically - joint space reduction due to loss of cartilage
- Osteophyte formation at joint margins
- Remodelling of adjacent bone
- Brown/yellow discolouration
- Synovial hypertrophy
- Capsular fibrosis
May affect one or multiple joints
May or may not be symptomatic
Pathogenesis:
- Not entirely clear but linked to loss of proteoglycans and subsequent lubrication
- Increased water content due to improper binding -> softening of cartilage = chondromalacia