Rapamycin.

Purpose of the Study Pulmonary metastasis continues to be the major cause of mortality among human and canine patients with osteosarcoma. A series of investigational agents will be evaluated in dogs with appendicular osteosarcoma with the hopes of identifying new drugs that help dogs live longer after being diagnosed with osteosarcoma. Rapamycin is a drug that may help slow down the progression of cancer cells, by blocking a pathway that helps cancer cells grow and opening up a pathway that promotes cell death. In doing so we hope that rapamycin would slow the spread of osteosarcoma to different parts of the body, most commonly the lungs. It is hoped that slowing the progression of osteosarcoma will result in longer survival of dogs diagnosed with osteosarcoma. Should you decide to enroll your pet into this clinical trial, your dog will receive standard of care therapy, which includes amputation and four doses of carboplatin given once every three weeks. After your pet completes the carboplatin therapy they will begin receiving rapamycin, which will be given once daily at home Monday–Thursday for up to four months.