January 2014 Small animal case

Dog Pudel.

10 Months of age.

Female castrated.

Presented for pain at left hip extension and bilateral grade III patellar luxation.

Radiographs of the hip in extension and flexion were taken.

Radiographic examination

Ventrodorsal view of the pelvis with hind limbs in extension.

Radiographic examination

Ventrodorsal view of the pelvis with hind limbs in flexion (frog-leg).

Radiographic findings

  • There is severe misshaped left femoral head with flattening, ill defined borders, shortening and widening of the femoral neck.
  • The opacity of the femoral head around the physis is heterogenous with multiple, ill defined areas of lysis (arrow).
  • There is severe asymmetry of the hip joint. The left one as a shallow acetabulum of heterogenous radioopacity and loss of definition of the subchondral bone (open arrows).
  • The left femoral head is subluxated cranially.
  • The left joint space is widened.
  • The muscle of the left tight are atrophic.

Radiographic findings

Close up of the VD frog leg view of the hip joints

Radiographic diagnosis

  • The radiographic diagnosis was chronic left hip joint luxation with avascular necrosis of the femoral head (Legg-Calvé-Perthes disease).
  • Secondary muscle atrophy and malformation of the acetabulum.
  • Differential diagnosis as erosive arthritis was considered less likely.
  • A surgical approach was elected, post OP radiographs are shown.

Radiographic examination

Post OP VD view of the pelvis.

Comments

  • The histological examination of the resected femoral head was ‚degeneration in the area of the physis with reactive proliferation of connective tissue and no sign of septic arthritis‘.
  • The avascular femoral head necrosis is an inherited autosomal recessive trait that is most often seen in immature toy and small-breed dogs.
  • Affected dogs are usually aged between 4 and 10 months of age.
  • The earliest radiological findings may be sublte with a slight radiolucency of the femoral head and widened joint space.
  • As the necrosis progresses there is lysis and collapse of the femoral head.
  • Later, there is osteoarthrosis with remodelling of the femoral head, resulting in coxa vara.
  • These later changes can minimic hip dysplasia, especially if bilateral.