Canine Osteosarcoma - Bone Cancer in Dogs
Osteosarcoma Bone Tumors are Aggressive & Painful Cancers for Dogs
May 8, 2009
Canine osteosarcomas are tumors or cancers in dogs which affect the bone. Any bone can be affected with an osteosarcoma, but most commonly osteosarcomas in dogs form:
- immediately above the stifle or knee joint
- immediately below the stifle or knee joint
- just below the shoulder joint
- just above the wrist (carpal) joint in the front legs
Canine osteosarcomas occur most commonly in large breed dogs.
Symptoms of Canine Osteosarcoma
Canine osteosarcoma most often presents as lameness affecting the leg in which the bone cancer is present. The lameness may start out being intermittent but as the tumor increases in size and involves more damage to the bone, the cancer becomes more painful and the lameness becomes permanent for the dog.
A swelling in the bone at the level of the tumor formation may be evident as a hard swelling in the leg of the dog.
Bones affected with osteosarcoma tumors are weakened by the cancer formation within the architecture of the bone and may break easily as a result, causing pathological fractures.
When metastasis (spread of the tumor or cancer) has occurred, the affected dog may cough or gag. The most common areas of metastasis are the lungs.
Diagnosis of Canine Osteosarcoma
Radiographs are often suggestive of canine osteosarcoma. However, other types of bone tumors need to be ruled out as well as fungal and bacterial infections which can cause similar lesions. Bone biopsies are usually necessary to make this differentiation.
Treatment of Canine Osteosarcoma
Treatment of canine osteosarcoma involves relieving the pain caused by the bone cancer and slowing the spread of the cancer through the rest of the body.
Two types of surgical procedures can be performed to remove the bone tumor itself:
- amputation of the affected limb of the dog
- limb-sparing surgery to remove the bone tumor but spare the remainder of the leg
Both of these procedures are considered to be treatment to control pain. Metastasis of the tumor to other parts of the body has usually already occurred by the time diagnosis of osteosarcoma is made, so removal of the primary bone tumor is rarely curative.
Pain Relieving Drugs Used to Treat Canine Osteosarcoma
Numerous drugs are commonly used to control the pain associated with osteosarcoma bone cancers in dogs. These drugs include:
- non-steroidal anti-inflammatory (NSAID) medications, such as Rimadyl, Deramaxx, Etogesic, Metacam and others
- tramadol
- gabapentin
- amantidine
These medications are often used in combination with one another to provide more extensive pain relief for the dog.
Radiotherapy is also sometimes used to help control the pain of dogs with osteosarcoma bone tumors.
Chemotherapy as Treatments for Canine Osteosarcoma
Chemotherapy is the only effective way to treat osteosarcoma because of the fact that spread (metastasis) of the cancer has usually already occurred by the time the bone tumor becomes evident. Canine osteosarcoma is a very aggressive form of bone cancer, rapidly spreading to other areas of the canine body.
Chemotherapy protocols vary depending on the individual situation but chemotherapy agents include:
- cisplastin
- carboplastin
- doxyrubicin
- doxyrubicin and cisplastin combined
Each of these medications has advantages and disadvantages in treating canine osteosarcomas.
Median survival times in dogs treated for canine osteosarcoma vary but are often less than one year.
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