If your dog was recently diagnosed with bone cancer affecting the leg, you may be wondering what treatments options for dog osteosarcoma are out there. Bone cancer in dogs is not an immediate death sentence, owners have several options and have some time to think things over.
As of today, the traditional standard of care treatment option for dog appendicular osteosarcoma (bone cancer of the leg) entails amputation of the leg and chemotherapy. Your vet most likely already discussed these options with you, but there may be several more and these may be further discussed upon meeting with a veterinary oncologist who can plan a protocol based on a dog's individual factors. Following is a summary of some traditional and less traditional treatment options for bone cancer in dogs.
Not Doing Anything
Some dog owners may wish not to do anything to treat dog osteosarcoma other than providing pain medications.
This decision may stem from financial issues (treatment for canine osteosarcoma can be quite costly) to dogs not being good candidates for treatment (neurological problems or severe arthritis), to the personal decision of letting the disease naturally run its course while trying a holistic approach.
Without any treatment, survival times for dog osteosarcoma are quite short, just around 4 to 5 months, whether or not amputation is done, explains veterinarian Dr. David Janssen.You can therefore just give pain meds, but the pain relief will not be effective as with amputation, considering the intense pain caused by the cancer.
Common pain meds prescribed include anti-inflammatory medications such as metacam, previcox or deramaxx combined with narcotic-type drugs like Tramadol. Pamidronate, is another option for dogs experiencing pain from bone cancer.
Palliative therapy consists of radiotherapy and chemotherapy for dogs who will not be getting an amputation.
The standard protocol involves radiation therapy for several consecutive weeks along with chemotherapy provided along with radiotherapy during the the first and final rounds of chemo.
Palliative therapy is not meant to really treat but to just provide pain relief that works better than oral pain meds alone.
Dog owners may expect reduced pain and inflammation, which leads to better mobility and therefore higher quality of life. The word palliative indeed simply means "relieving pain without dealing with the underlying cause of the condition."
Palliative radiation and chemo generally generates a life expectancy of about 6 months. Some dog owners may elect to do palliative radiation without chemo, but better long term results are attained when radiotherapy is used along with chemo.
When dogs develop bone cancer, the cancer starts eating up the bone. This is a very painful process. As the bone is eroded, its structure weakens which can lead to a sudden and painful fracture ( medically known as pathological fracture).
Amputation prevents a potential pathological fracture and removes the source of pain, allowing dogs to get relief. Generally amputation alone provides a median survival time of 4 to 5 months of life.
Why is amputation necessary in dogs with bone cancer? It's unfortunate, but the bone alone cannot be removed and therefore removing the whole leg is therefore the only solution, explains Dr. Ettinger. Costs for a dog leg amputation may range anywhere from $500 to $1500.
"Survival times for OSA cases with amputation and no other treatment have a median survival time of four to five months, with 90-100% dying by one year, and only 2% still alive at two years."~Dr. Susan Ettinger, veterinarian specializing in oncology.
Amputation with Chemotherapy
Dog osteosarcoma needs to be fought on two fronts: locally by removing the cancer through leg amputation and systemically by fighting spread to the lungs which occurs secondary to bone cancer (when caught early, it's called micrometastasis and cannot be detected on x-rays).
It is unfortunate, but it is the spread to the lungs that causes death in dogs with bone cancer. Around 90 percent of dogs have micrometastasis when they are diagnosed with bone cancer, and 95 percent will develop detectable metastasis later on, as the cancer progresses.
If there are signs of detectable spread to the lungs that are visible on x-ray (they appear as nodules), things are more advanced and chemotherapy is not recommended, explains Dr. Laura D. Garrett, a veterinarian specializing in oncology. Detectable signs of spread of cancer are fortunately seen only in about 8 percent of dogs at the time of diagnosis.
Chemotherapy will take care of the micrometastasis spread to the lungs, allowing remission times. Chemo is typically performed once every three weeks for a total of four doses. As much as chemo sounds like a bad thing, the good thing is that unlike in humans, chemo in dogs is very well tolerated, and the side effects are often minimal. Commonly used chemo drugs include doxorubicin, carboplatin, and cisplatin. There is lately interest in metronomic chemotherapy and cisplatin-impregnated beads.
The earlier the chemo is started after surgery, the better. Starting chemo about two weeks after surgery is a good plan. Generally, dogs undergoing amputation along with chemo have survival times of about 1 year.
"Median survival times for OSA cases with amputation and chemotherapy increase to ten to twelve months, with 20-25% of dogs are still alive at two years."~Dr. Susan Ettinger
Limb Sparing Surgery
It's important to emphasize that not all dogs are candidates for amputation and chemo. The only candidates for limb sparing surgery are dogs with bone cancer localized to the lower part of the front leg, the wrist to be exact (distal radius). In this surgery, the cancer is removed and replaced with an implant. The implant is typically made of titanium and consists of rods and plates.
The wrist joint is then fused with the bone and implant so the joint is stabilized enough to allow dogs to carry on with their regular activities. As much as this option seems appealing, it must be considered that it is not free of complications. On top of that, it's quite expensive too. The cost for the surgery alone can range between $4,000 and 5, 000.
Generally, dogs undergoing limb sparing surgery with chemo have survival times around the same time frame as dogs with regular amputation and chemo, anywhere between 10 and 12 months.
When amputation is not an option, either because of potential side effects or the owner refuses it, on top of limb-sparing surgery, there is another option: stereotactic Radio Surgery. Unlike palliative treatment which focuses only on relieving pain, radiosurgery focuses on destroying tumor cells through radiation.
In particular, CyberKnife Radio Surgery, is quite effective due to its accuracy in radiating target areas. For bone cancer, Cyberknife usually entails three treatments. A CT scan or MRI prior to treatment is important so to assess the level of bone destruction and whether Cyberknife is an option. Cyberknife is not recommended if the bone is close to fracturing.
Because bone cancer spreads to the lungs, it's important that radio surgery is followed by chemo. Radiosurgery deals with the localized cancer, while chemo takes care of the spread. When combined with chemo, Cyberknife generates survival times of about 1 year, which is similar to to the life expectancy in dogs undergoing amputation and chemo.
Cyber Knife is currently offered by Dr. Susan Ettinger in New York, the University of Florida, Colorado State University, and a unit in California offers it as well.
"So far the results at my hospital show that dogs receiving CK and chemotherapy (to control metastasis) have a survival time of about one year.... If you want to save your dog’s limb, if you can afford radiosurgery, if you can get to a hospital which offers it, and if your dog is a good candidate, this may be a good option to consider."~Dr. Susan Ettinger
- Davies Veterinary Specialists, Canine Osteosarcoma
- Dog Cancer Blog: Chemotherapy for Osteosarcoma
- Dog Cancer Blog: Osteosarcoma: when amputation is not an option, part 1, 2
- DVM360: Osteosarcoma and hemangiosarcoma: The ugly sarcomas (Proceedings)
- Wendy Berry, Diesel the three legged dog, Flickr Creative Commons CCBY2.0