OSU and many others on Greytalk recommended the fine needle aspirate instead of the bone biopsy to confirm that Snickers had bone cancer. It ended up not being a definitive result but I think that besides the pain of the bone biopsy, I decided on the FNA because there was the possibility of shattering the bone during the regular biopsy. Osteosarcoma has a very distinctive appearance on x-rays and after OSU looked them over it seemed pretty certain that osteosarcoma was what we were dealing with.
After they amputated, they send the leg (or part of it) for testing, and it was confirmed that Snickers did have osteosarcoma.
Hugs to your friend and their dog. Many pups have successful surgeries and do well for a while afterward.