Introduction

• An aseptic necrosis of the femoral head of small breed juvenile dogs, particularly Terriers, Poodles, and Miniature Pinschers - associated with autosomal recessive gene. Males and females are equally affected.
• Signs: gradually progressive unilateral or (less commonly -10-17%) bilateral hindlimb lameness, pain, restricted joint movement. Concurrent medial patellar luxation may be present.
• Diagnosis: radiography.
• Treatment: non-weight-bearing sling if identified prior to bony collapse; excision arthroplasty or total hip arthroplasty if identified after bony collapse.
• Prognosis: good.

Pathogenesis

Etiology

• Inherited predisposition associated with multifactorial pattern in Manchester terrier.

Pathophysiology

• Infarction of epiphyseal and metaphyseal bone.
• Ischemia of femoral head and neck followed by necrosis and trabecular collapse, and deformity of subchondral bone.
• Articular cartilage cracks as its supporting bone deforms.
• Results in articular incongruency and joint instability.
• Later, highly vascular granulation tissue penetrates head and replaces dead bone by creeping substitution.
• Finally, degenerative changes develop as a result of articular incongruency.

Diagnosis

Treatment

Prevention

Outcomes