9-Month-Old FS Chihuahua

Signalment & History

A 9 month old FS Chihuahua presents  for progressive, non-weight bearing, right pelvic limb lameness. On orthopedic examination, the right coxofemoral joint is subluxated and the right hind limb musculature is severely atrophied. Additionally, the right femur appears shorter compared to the left. Otherwise, the remaining physical examination findings are normal.

Right lateral pelvis VD pelvis


The right femoral head and neck are severely misshaped, irregularly marginated, and increased in opacity; indicating sclerosis. The right acetabulum is widened and shallow. There is loss of congruency of the coxofemoral articular surfaces. The right gluteal and thigh muscles are severely thinned. The left femur and surrounding soft tissue structures are normal.


  • This patient is diagnosed with right coxofemoral joint aseptic necrosis of the femoral head with associated severe diffuse muscle atrophy.
  • This disease is also commonly known as Legg-Calve-Perthes disease.


Legg-Calve-Perthes Disease (Aseptic necrosis of the femoral head)

  • Signalment: young, small breed dogs
  • Etiology: unknown
  • Ischemia and infarction of the bone leads to collapse of the femoral head and neck, followed by revascularization, resorption, and remodeling.
  • The lesion is often bilateral.
  • Chronic cases have evidence of degenerative joint disease.