Treatment & Prognosis for Bone Cancer (Osteosarcoma) in Dogs
Goals of Treating Bone Cancer
The goals of treating a dog that has osteosarcoma are to relieve pain and prolong the pet’s disease-free quality of life for as long as realistically possible. Because osteosarcoma tends to spread rapidly, it should be taken very seriously and treated aggressively. The lungs are often one of the first places that osteosarcoma migrates to. X-rays (radiographs) of a dog’s chest may be recommended before it is placed under anesthesia to undergo surgery, in order to determine whether the cancer has spread to its lungs and, if it has, how advanced the dog’s disease has become. If any of the lymph nodes are swollen, the veterinarian may take samples using a fine needle aspirate procedure. This technique involves inserting a sterile needle into the suspicious lymph nodes and withdrawing a tiny amount of tissue, fluid and cells from those nodes by pulling back on the attached syringe. The aspirated samples will be expressed from the syringe onto glass slides and examined under a microscope.
When osteosarcoma affects a dog’s leg, the standard course of treatment is surgical amputation. Most dogs handle this fairly well and seem relatively unaffected by having only 3 usable legs. This is especially true if all or part of one of the hind legs is removed, because dogs do not carry as much of their weight on the back legs as they do on the front. New surgical techniques are being developed that may enable veterinarians to save a dog’s limb by removing the cancerous portion and sparing the remainder of the leg. These procedures are only available at specialized veterinary teaching hospitals and surgical referral centers. At this time, salvage operations have more complications, such as infections and tumor recurrence, and the same average survival times, as does amputation. Most veterinarians suggest amputating the leg from at least one joint above the affected area. Hopefully, this will relieve the pain associated with osteosarcoma and improve the dog’s overall happiness, contentment and enjoyment of life.
Surgery is also the preferred treatment for a dog that has osteosarcoma in its ribs, spine, jaw or other facial bones. All of the affected bones should be removed. Unfortunately, in many cases, complete excision is not possible because of the location of the tumors near vital blood vessels, nerves and other key structures.
Radiation and chemotherapy can be used as adjuncts to surgery in dogs with osteosarcoma. The protocol for chemotherapy usually involves giving intravenous drugs every few weeks for a set period of time. This must be done in a hospital, usually at a referral center under the supervision of veterinary cancer specialists called oncologists. Chemotherapeutic agents are very potent. Using them can be unpleasant and even dangerous for the dog. Basically, these drugs enter the dog’s bloodstream and circulate throughout its body, targeting and killing rapidly-dividing cells, including cancer cells. However, chemotherapy drugs also target a number of normal rapidly-dividing cells, like those lining the stomach, intestines and hair follicles. Nausea is a common consequence of chemotherapy, as is hair loss. Chemotherapy may increase the survival time of dogs with bone cancer, but it rarely accomplishes a complete cure. Because osteosarcoma is so aggressive, it almost always will have spread by the time it is diagnosed. Owners of dogs with osteosarcoma will want to consult with a veterinary oncologist before embarking upon a course of surgery, radiation or chemotherapy.
Some owners decide not to pursue any of these treatments, for a variety of different personal reasons. Their dogs can still benefit from good supportive care for the rest of their lives. Oral pain medications (analgesics), such as non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, can be helpful. Prescription pain-relieving patches, which slowly release small amounts of potent anti-pain drugs directly through the dog’s skin, are also available. Sadly, many dogs with osteosarcoma are euthenized shortly after their diagnosis is confirmed. This is a realistic option for some owners. Osteosarcoma is a painful and potentially fatal disease. Chances are good that it has already spread from bone to other tissues by the time it is discovered in our companion dogs.
Most dogs with osteosarcoma will eventually succumb to the effects of their disease, with or without treatment. Dogs with bone cancer in one of their legs typically live only 4 or 5 months after that limb is amputated; roughly 10% will survive up to a year after surgery. When amputation is combined with chemotherapy, the average survival rate increases to about 6 to 12 months, at the most. If no treatment is done, dogs with osteosarcoma usually only live for a month or two after their disease is diagnosed.