[anonymous]

Did the vet do x-rays? What you describe sounds like what happened to my dog “hemangiosarcoma”. It usually strikes dogs between 8 and 10 years of age. Often no symptoms till it is too late, genetic in nature, tends to occur in certain breeds such as German Shepherds.
The anemia and difficulty breathing indicates tumors and mets to the lungs.
Whatever the case. I’m sorry for your loss.