2 weeks ago my 13 year old australian cattle dog mix started acting strangely with anxiety and groaning and appetite change. An abdominal film done at my primary vet showed a large amount of ascites (fluid in the abdomen). She sent me to a speciality VCA hospital where a chest xray was done. Turned out that he had a mass in his heart. He had a pericardiocentesis to drain 250ml of fluid from around his heart which made him immediately more comfortable. They were not sure if this mass was an aggressive cancer (hemangiosarcoma) or a slower growing mass (chemodectoma). If it was hemangiosarcoma, he probably would only live a few weeks to a few months. If it was a slower growing form he could have lived up to two years. The cytology was inconclusive-- it only showed a hemorrhagic effusion. I guess heart base tumors don't always shed cells that are seen in effusions. He began to have shortness of breath and ascites (fluid in belly) only 48 hours after the pericardiocentesis. They offered a procedure where they remove the pericardium so that the fluid just escaped into the thoracic cavity. But I decided it wasn't fair to put him through that at 13 years old not knowing how much time or quality of life it would give him. He was very uncomfortable the morning I decided to let him go. He was up every 30 minutes the night before, he was groaning again and his little body trembled with every breath. The vet came to the house and put him to sleep that afternoon. He surprisingly (and crazy-making for me) met the vet at the door and he didn't seem in distress when she was there. He even ate a bowl of turkey. It was so confusing to me as he seemed to be suffering the 36 hours prior. I miss him so much. He was my constant companion the last 13 years. It all happened so fast. And I am lost without him. I question whether I did the right thing by letting him go that day or if I should have waited. I was scared for him to get worse and possibly die alone while I was at work.