Hypertrophic Osteodystrophy

Hypertrophic osteodystrophy (Image sourced from Bristol Biomed Image Archive with permission)

• Also called - metaphyseal osteopathy
• Young (usually 3-6 months old), fast growing dogs of large or giant breeds
• Distal radius and ulna most severely affected
• Clinical signs:
  • Fever
  • Anorexia
  • Severe lameness
  • Swelling in metaphyses of long bones corresponding with neutrophilic infiltrate
• Radiologically:
  • Increased lucency and increased density areas in metaphyses
  • Enlarged metaphyses
• Usually bilaterally symmetrical
• Histologically:
  • Haemorrhage and necrosis of osteoblasts in the growth plates and primary spongiosa
  • Intense infiltration by neutrophils
  • Periosteal reaction + formation of new bone on external surface above the lesion
• Many resolve spontaneously with complete remodelling and healing of the bone
• Can progress to periosteal bone proliferation
• Cause is unknown
  • Unlikely to be dietary deficiency
  • Likely to be infectious cause
• Contrast with canine panosteitis