Large and giant breed dogs are the most at risk for developing a tumor of the bone called osteosarcoma. In the U.S., more than 10,000 dogs are diagnosed with osteosarcoma each year. While amputation remains the most common treatment for a bone tumor arising in a limb, some dogs are not good candidates because of concurrent orthopedic or neurologic disease. Additionally, some owners are opposed to amputation. Amputation can also lead to some negative changes. In two studies, 20% of owners reported a decrease in their dog’s recreational activities after amputation, 38% reported a reduction in their dog’s stamina during exercise, and 9% to 32% reported behavioral changes including increased aggression toward other dogs, increased anxiety, decreased dominance, and lack of interest in other dogs.
While most dogs will have an excellent quality of life with an amputation, for dogs who are not good candidates or for owners who are opposed to having an amputation done for their companion, there are other options to treat the tumor while preserving the limb and its function. One of those options is surgical limb-sparing.
Limb-spare surgery has been performed in dogs for more than 30 years. The technique was pioneered at Colorado State University by Dr. Stephen Withrow and was developed to provide an alternative for dogs who could not do well with an amputation. As the name implies, the surgery entails removing the segment of bone harboring the tumor and reconstructing the limb while preserving its function. There are many different techniques to reconstruct the piece of missing bone. At the inception of limb sparing, the missing piece of bone was replaced by an allograft (a bone donated from another dog, with its owners’ permission, after having died of reasons unrelated to cancer). Since then, several other techniques have been developed: using a metal implant and using a different bone from the patient are examples.
While limb-spare has advantages, there are often complications with this surgery. In fact, complications are likely to happen, including infection, biomechanical problems (such as the implants fail or the remaining bones fracture), and recurrence of the tumor in the limb. Additionally, there are locations where surgery is not an option, such as tumors close to the shoulder (top part of the humerus).
Is my pet a good candidate for limb-spare surgery?
The location of the tumor that is most amenable to limb-sparing is just above the equivalent of our wrist joint (bottom part of the radius) in the front forelimb. Most dogs achieve good to excellent function and quality of life with this treatment. The wrist joint is fused during this surgery, and dogs tolerate it very well. The average survival after the surgery and chemotherapy is 50% at one year and 25% at two years, which is the same as dogs receiving an amputation and chemotherapy.
Advances in limb-spare surgery
We are constantly in search of new ways to decrease the complications associated with limb-spare surgery to increase the quality of life and survival times of our patients. As a result, limb-spare surgery is an ongoing area of research at the Flint Animal Cancer Center. One of the newest limb-sparing techniques utilizes 3D-printing to make a personalized implant for each dog. While this technology has been used to provide limb-sparing in dogs with tumors close to the wrist, newer implants are being developed for tumors close to the shoulder. This will hopefully provide an alternative for dogs where there is currently no surgical option. We also hope the dogs who get these new custom implants have fewer biomechanical and infection complications.
The FACC has offered specialized high dose radiation therapy, called stereotactic radiosurgery, as an alternative to surgical limb-spares, in certain cases, for about a decade. The survival times are similar to dogs who receive amputation, but this is a much less invasive option. This is also referred to as a radiation limb-spare. Because osteosarcoma weakens the bone and puts the patient at risk for fracture, this has not been a treatment option for dogs who have had significant bone loss at the tumor site or already have a fracture. Previously, amputation was the only treatment option. Our team is looking at a novel approach to inject sterile bone cement into the tumor to strengthen the bone and then to proceed with radiation therapy. We hope this may prove to be another good treatment option with fewer complications.
Limb-spare surgery at the Flint Animal Cancer Center
The Flint Animal Cancer Center oncology service includes four surgical oncology faculty, two surgical oncology fellows, and a dedicated surgical oncology technician. Our experienced surgeons conduct 400+ surgeries each year. For more information about limb spare surgery to treat osteosarcoma, please email email@example.com.