Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Four The Appendicular Skeleton 579
Fig. 4-131 A 10-month-old male Yorkshire Terrier had been lame
since 4 months of age. It was reluctant to bear weight on the right rear
limb and had muscle atrophy. There is marked collapse of the cranial
dorsal aspect of the right femoral head, with a decreased density in the
subchondral bone beneath this flattened area. There is a loss of bone
density in the right acetabulum and subluxation of the right coxofemoral
joint. Diagnosis: Osteonecrosis of the right femoral head.
The severity of the radiographic changes is indicative of a long-standing
condition. The left coxofemoral joint is normal at this time.
Fig. 4-132 A 5-month-old male Pekingese was evaluated for a left
rear leg lameness that had been present for 4 weeks. Both femoral
heads are deformed and there is decreased density involving the ventrocaudal
aspect of the left femoral head and neck. There is subluxation
of the left coxofemoral joint with fragmentation of the left
femoral head. Areas of decreased density involve the cranial dorsal
aspect of the right femoral head. Small bone densities are present in
the area of the articular surface. There is subluxation of the joint. A
slight increased density involves the proximal metaphysis of the right
femur. Diagnosis: Bilateral osteonecrosis. The changes in the right
side appear to be more recent.