In my most recent blog, we discussed amputation for limb osteosarcoma (OSA), the most common local treatment for the primary tumor in the bone. We discussed that amputation is not an easy decision for pet Guardians, even though most older dogs with average, moderate arthritis usually do well on three legs. If my clients are unsure, I typically consult with my orthopedic surgeon, who can help us decide if surgery is an option.
Amputation may not be right for every dog or every pet Guardian. Dogs with very severe arthritis and some neurological conditions may not be able to walk well after an amputation. And some owners are reluctant to amputate. So what are the alternative options?
Collectively, these alternatives to amputation are often referred to as limb-sparing procedures, because they spare the dog’s leg. Remember, these limb-sparing techniques do not address metastasis or micrometastasis. Osteosarcoma is an aggressive cancer, and almost always metastasizes — so don’t forget the chemotherapy to address spread.
There are three “alternatives-to-amputation” that I will touch on in this post and the next: palliative radiation, limb-spare surgery, and stereotactic radiosurgery.
Palliative radiation: to relieve the pain
Palliative-intent radiation therapy offers better pain control than oral pain medications, but not necessarily longer survival times than amputation alone. (Remember, palliative means it helps, but does not cure.) Palliative radiation is aimed at reducing pain and increasing quality of life in dogs that do not get an amputation. The palliative protocol usually involves two to four once-per-week treatments. Palliative radiation can reduce inflammation, lessen pain, improve the dog’s ability to walk, and aid in the healing of micro-fractures.
I like this option when amputation is not an option and cost is a consideration. The majority of dogs do well after radiation—75 to 90% experience positive effects, usually within one to two treatments. For some dogs, these effects last for only months, while others for over a year (if metastasis is controlled too). During this time most dogs need less pain medication, or no pain medications at all. We’re not sure exactly why, but it is thought that radiation therapy releases pain-killing endorphins. Chemotherapy treatments given in addition to palliative radiation has also been associated with better long-term results than palliative radiation alone.
Limb-spare surgery: still surgery, but the leg is saved
Limb spare surgery is a complicated surgery. These procedures vary depending upon the case, but usually involve removing only the tumor-affected bone, and then replacing it with a bone from a donor or the patient. The new implant must be plated and fused, which may not be possible in every location; the ends of the radius and ulna bones at the wrist are the best locations for limb-sparing procedures. To be a candidate, your dog must have less than 50% of the bone affected by the OSA, no fractures, minimal soft tissue involvement, and a lesion that does not wrap around the whole bone.
Limb-sparing surgeries are more involved than an amputation, more expensive, have more complications than amputations, and require a specialty hospital with the ability and experience to perform the advanced techniques involved. Survival times remain the same as amputation plus chemo, and these dogs have higher recurrence rates (20-30%). Interestingly, dogs who develop infections are more likely to have overall successful surgeries and live longer, likely because the immune system’s response is strengthened by fighting the bacterial infection.
Stereotactic RadioSurgery, or SRS, can also be used as a limb-sparing technique, but it takes some time to explain, so I will address that in the next post.