Best of luck with Jolene. Yes, Comet had chest xray (and liver biopsy, kidney ultrashounds, blood tests, urine tests, retinal biopsy, a blur of others) and was clean. We lost his right eye to blasto.
Your topic title brought back memories. I thought that Comet's diagnosis of blasto was my worst nightmare too ...until the vet said he was permanently blind which was my nightmare until the vet said he would have to have his blind eye removed, which was the new one. ...soon to be replaced by the notion that he could DIE. Now THAT put it all into perspective.
My Comet lost his eye and suffered much pain, but he is alive and right here beside me. I am one lucky person indeed, and I never forget it for one minute. It took a long time (over a year) before I would let Comet run along the creek again, and I still fear it. Now I watch him and call out the command I wish he never needed to learn "NO DIGGING!". I can't protect him from blasto spores because of what it would do to his quality of life (and mine). So, I try to make up for it with the best diet I can give him, learning, and watching, watching, watching, for any out of character symptoms or behavior. This forum is so important in helping me to stay vigilant.