Objective— To report the occurrence of medullary bone infarction in both femoral canals after bilateral total hip arthroplasty (THA) and the subsequent unilateral development of an osteosarcoma at the site of bone infarction.

Study Design— Clinical report.

Animal Population— An 8-month-old neutered male Samoyed dog.

Methods— Serial physical and radiographic examinations performed at 1, 2, 3, and 5 years after THA. Bone biopsy specimens of the right distal femoral metaphysis were taken 5 years after THA, and a complete necropsy was performed at the time of euthanasia.

Results— Bilateral medullary bone infarction was visible in the femoral canals 1 year after THA and remained visible on subsequent evaluations. An osteosarcoma developed in the right distal femoral metaphysis at the site of infarction, 5 years after THA, and was found to have metastasized widely throughout the body.

Conclusion— Bone infarction may occur in the femoral canal after canine THA.

Clinical Relevance— Bone infarction may be a predisposing factor for the development of osteosarcoma in the femora of dogs with THAs.