Osteosarcoma is a relatively common type of cancer that affects our pet dogs. It's typically diagnosed in larger breeds, including Rottweilers and Greyhounds. It's a very aggressive type of cancer and the recommended treatment usually involves removal of the affected leg. This helps to prevent further spread of the tumor.
Most dogs do just fine with three legs, but amputation can make life difficult for giant breeds that have to rely on their remaining legs to support their weight. It's also not ideal for dogs with arthritis or other medical conditions that affect their gait or balance. Veterinarians are now able to offer limb-sparing options that allow dogs with osteosarcoma on the lower part of the radius to avoid amputation. Here are four different limb-sparing techniques:
Bone Graft from a Cadaver
Surgeons can sometimes remove the part of the limb bone that's affected by cancer and replace it with a bone graft from a deceased donor dog. However, this solution has a very high risk of the recipient dog developing osteomyelitis, which is a serious bone infection that can be difficult to treat. Should this type of infection occur, it's likely that the affected limb would need to be amputated anyway.
Ilizarov Technique
For dogs with only small areas of bone that are cancerous, the Ilizarov technique can be used to re-lengthen the leg. After the affected area of the bone is surgically removed, a specially designed cage-like apparatus is placed externally around the dog's leg and attached to pins that penetrate the bone. The bone is then pulled apart by a small amount on a regular basis, which encourages the growth of new bone in the space until the bony defect is filled. The main disadvantage of this technique is the slow rate of healing – it can take many months for the space in the bone to be closed.
Endoprosthesis
Another limb-sparing technique is the replacement of diseased bone with an endoprosthesis instead of a bone graft. This consists of a metal rod that is inserted into the gap left when diseased bone is removed, and screwed to the remaining healthy bone to keep it in place. This is very effective but there is a risk of failure of the prosthesis due to screw breakage or loosening.
Bone Graft from Patient
Finally, perhaps one of the best options for dogs that are candidates for limb salvage is a living graft. Here, the affected section of bone is removed and replaced with a healthy portion of the dog's own ulna bone (if the resected area is from the radius). The blood supply to the bone can be maintained with microsurgery techniques to reconnect blood vessels, and the bone often heals more quickly than with the other methods described above. However, this surgery takes longer to perform, and can only be done when blood supply can be maintained.
The prognosis for dogs with osteosarcoma varies depending on their age, the location of the tumor, and whether there are signs of spread to other parts of the body. Surgery, whether an amputation or limb-sparing procedure, combined with chemotherapy and radiation therapy, will give an affected dog the best possible outcome.
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