Osteosarcoma is a frightening diagnosis. According to Purdue University's Animal Disease Diagnostic Laboratory, it accounts for up to 85 percent of all bone tumors in dogs, and more than 90 percent of the tumors have already spread to the lungs and other bones by the time of diagnosis. Osteosarcoma deaths are generally caused by either the spreading of the tumor or euthanasia due to pain, so treatment depends upon both fighting the cancer cells and relieving the severe discomfort associated with the disease.
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Surgery
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Osteosarcoma pain comes from the tumor growing inside the bone and putting immense pressure on the surrounding tissues. Soon, normal bone is entirely replaced by cancerous bone. Amputation of the affected limb eliminates the pain completely, and most dogs resume normal activity without a problem. In some cases, when the tumor is located very low on the limb, a bone graft can help the dog avoid amputation. However, limb-sparing surgeries carry the risk of infection, implant failure and tumor reoccurrence. Dogs that are very overweight or otherwise unhealthy may not be candidates for surgery.
Pain Medication
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Mar Vista Animal Medical Center likens the pain of osteosarcoma to a "slowly exploding bone" and adds that most pain relievers will not completely rid the dog of pain. Veterinarians prescribe various analgesics from carprofen to fentanyl for whatever help they can give, but they are not effective for long-term pain relief.
Radiation Therapy
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Radiation therapy provides pain relief and improved limb function in about two-thirds of dogs treated. Given in three separate doses, results are normally seen within three weeks, and last an average of about four months. Radiation therapy can be very expensive and is generally only available from veterinary oncologists or veterinary schools.
Chemotherapy
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Because osteosarcoma is such an aggressive cancer, chemotherapy is the only effective way to treat it. There are a variety of drugs given either separately or in combination that can increase the dog's life expectancy significantly, and make him more comfortable for the time he has left. The most common "cocktail" is a combination of doxorubicin and cisplatin, although both can be given separately as well. Dogs do not suffer as much as humans do while undergoing chemotherapy, the most common response being a day or two of lethargy and nausea. Chemotherapy drugs are very expensive, and because they are very toxic to the dog's system, cannot be given to dogs with kidney disease.
Prognosis
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Dogs with osteosarcoma that do not receive chemotherapy have a life expectancy of four to five months after diagnosis whether the affected limb is amputated or not. Chemotherapy can add up to three years to the dog's life depending upon what drugs are used, but the owner should be very careful to always consider quality of life over quantity of life. Osteosarcoma is one of the most painful diseases a dog can get, and it is the owner's duty to weigh the comfort and well-being of the dog against the pain of euthanizing a furry friend.
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