Our lab recently slipped on the stairs and went down pretty hard (on the last step). He limped and wouldn't put weight on it for a few hours. We went to the vet. They said potential ACL and gave pain meds. We went back for a checkup because he was still favoring it sometimes. He still trots around with a very minor limp, but it wasn't back to 100%. They xray and hit us with a referral to a surgery center. Potential osteosarcoma. I'm just in shock. He's perfectly healthy, no family history of this back 5 generations. After reading the prognosis for this thing I don't think I'll sleep until the next appt. Any thoughts or advice? Here is the xray.