This post isn't about Trey, but rather his older half brother, currently on 4 legs.  He started with a slight, sporadic limp around Christmas.  X-rays early January looked ok to our regular vet.  Rest and Rimadyl made zero improvements, so our vet referred us to a specialty clinic late January.  They did xrays, found a small bone lesion at the top of the humerus - less lysis than bone thickening.  Discussed that it was probably osteosarcoma, and while discussing amputation and chemo, also suggested stereotactic radiation and chemo.  No metastasis was visible  anywhere chest x-rays.  They in turn referred us to an cancer center that had cyberknife stereotactic radiation.  That clinic assumed it was osteosarcoma, did a CT and radiated the tumor.  Now, to have the chemo, they sent us back to the original specialty clinic.  The oncologist there said she was unable to help us with chemotherapy since the exact tumor type was never identified and the chemotherapies for osteosarcoma and histiocytic sarcoma are very different.  Since radiation had already been done, biopsying was no longer an option because it would damage already brittle bone.  She offered to try a needle aspiration guided by ultrasound, but had no promises.  Ultrasound of his full abdominal cavity still showed no visible metastasis.  Unexpectedly, they were able to get an identification from the aspirate.   Even more unexpectedly, it came back chondrosarcoma - a much better diagnosis as far a life expectancy, but we now have a dog with a 30-40% risk of pathological fracture.  There is no chemotherapy for chondrosarcoma.  So, the dog we expected to have a short life, now has a much better prognosis of living, but can never be allowed to bounce around or be a normal dog because of fracture possibilities.  He has had one Zolendronate treatment, and we are willing to continue them as long as he's doing well.  What have experiences been with Zoledronate?  I know there were studies 10 years ago, but does anyone have anything more recent?