24 Aug 2015
After a long day at the clinic, Ralph is your last appointment. He is an eight-year-old, male, neutered German shepherd dog presented with an acute onset of non-weight-bearing lameness on his left forelimb after running in the garden.
The orthopaedic examination reveals swelling, pain and malalignment of the distal antebrachium.
You suggest sedation and orthogonal radiographs of the distal radius and ulna as the first step of your investigations.
A transverse fracture of the distal radius and ulna is diagnosed. How will you manage this case?
Given the dog’s age and history, the radiographs should be assessed more carefully before heading for theatre.
On close inspection, areas of cortical lysis can be appreciated and there is no distinct border line between normal and abnormal bone (Figure 1).
Your provisional diagnosis is a pathological fracture of the distal radius secondary to a primary bone tumour.
Osteosarcoma is the most common primary bone tumour in dogs. While bone biopsy is the best method to confirm your diagnosis, this could necessitate a delay in treatment, resulting in significant morbidity for the dog. Therefore, biopsy could be omitted in this case.
Staging of the disease to check for gross metastatic disease is essential. Radiographic assessment of the thorax should consist of inflated left and right lateral, and ventrodorsal projections.
Radiography allows detection of pulmonary metastatic lesions larger than 7mm diameter; for detection of smaller lesions, a CT scan would be preferred. If any enlargement of regional lymph nodes is suspected, fine needle aspiration and cytology can be considered.
Management options for osteosarcoma can include euthanasia, palliative care, surgery to control the primary tumour and adjunctive chemotherapy. In this case, no pulmonary lesions were found, the local lymph nodes were normal, and haematology and biochemistry were unremarkable.
In the presence of a pathological fracture, a forequarter amputation is generally recommended; limb sparing surgery can be attempted, but achieving control of the primary tumour is much more difficult.
Following surgery, the entire limb can be submitted for histological evaluation.
The median survival time following amputation alone is around five months, but chemotherapy can increase this time up to one year post-surgery. Doxorubicin and carboplatin are used most commonly, either as single agents or in combination. In this case, a left forequarter amputation was performed; chemotherapy was declined by the owner.
The dog was still alive and doing well eight months after surgery.
