Dog Parvo Symptoms

Bone, joints and spinal tumors:

Osteosarcoma (OSA) is by far the most common primary bone tumor. Other primary bone tumors, such as Chondroma/chondrosarcoma, Hemangiosarcoma, Fibrosarcoma, and Multilobular osteochondrosarcoma (MLO, Chondroma rodens) may occur. A definitive diagnosis is not possible without a bone biopsy – but performing a biopsy risks causing a pathologic fracture at the biopsy site (because of the bone is so friable with tumor destruction). Thus, a final diagnosis is not always available. OSA tumors have a very high metastatic potential, and most patients already have microscopic pulmonary metastasis on presentation. Therefore, while radiation therapy is not usually curative and does not increase survival time, it is a very effective palliative treatment when surgery or amputation has been declined. Approximately 70% of these patients have a positive response to palliative radiotherapy. (Refer to handout subtitle Palliative radiation therapy for more detailed information.)

MLO generally occur on canine skulls and will often recur if not fully resected. Approximately 50% will metastasize (usually within the first year after treatment) and the median survival time is about 21 months. Although both chemo and radiation therapy have been administered to these patients, the exact role and efficiency of these adjuvant modalities are not yet well defined.

Feline osteosarcomas have a lower metastatic potential and, thus, a significantly better prognosis, compared to the same tumors in dogs. Median survival time in cats with osteosarcoma, with no evidence of metastatic disease, treated with amputation alone, is 2 years. Their better prognosis may make radiation therapy (not as a palliative approach) more reasonable in cases where complete surgical resection is not an option.

Multiple myeloma, Lymphoma of the bone marrow and bone metastases can be painful, and may be successfully managed with palliative treatment. As with primary bone tumors, radiation is not used to increase survival time but to control pain and offer local comfort in sites non-responsive to conservative medical treatment.

The prognosis of Synovial cell carcinoma is greatly dependent on the grade and stage of the tumor. Approximately 22 % have evident metastatic disease on presentation, and require chemotherapy. Grade III tumors (most malignant) are best treated with amputation +/- chemotherapy. When amputation is declined, aggressive local surgical resection followed by radiation therapy (+/- chemotherapy) is the most appropriate treatment. One reported isolated case, treated with surgery and radiation, showed no evidence of neoplastic disease 2 years after treatment (deceased from unrelated cause).

Spinal bone tumors (primary or secondary) have been treated with palliative radiotherapy – often on an emergency basis when they cause significant neurological signs and paralysis. Just as bone tumors of the limbs show a pain relief response to radiation, neurological improvement and pain relief has been observed as soon as a few hours to a few weeks following the initial radiation treatment of spinal bone tumors.

Normal lymphocytes are extremely radiosensitive. However, resistance to chemo and radiation therapy has also been noted. Little is reported regarding the response of Spinal lymphosarcoma to radiation. In one study one three cases of feline lymphosarcoma treated with chemotherapy and radiation therapy, two cats had a positive response to radiotherapy while one continued to deteriorate.

Tumors of the spinal nervous tissue – like brain tumors – generally respond to radiation in a similar fashion. When feasible, surgery combined with radiation should offer the best long-term prognosis. If both are combined as a treatment the total radiation dose is slightly decreased to reduce potential late complications. Therefore, these options need to be thoroughly discussed if initiating radiation before surgery.