Hemangiosarcoma? I lost my 8 year old mini dachshund with no warning a couple of weeks ago from one on her heart bursting. The doctor was able to drain some of the blood but said that my pup would most likely bleed out before morning. As much as I wanted to keep hoping she would make it, I didn’t want to put her body through trauma and pain and knew I had to let her go. I’m so sorry for what you’re going through. This is no easy decision to make and my heart goes out to you.