I'm so sorry Beth is ill. I've lost two dogs (a greyhound and a weimaraner) to hemangiosarcoma. My greyhound, Chloe, showed no signs of illness until the cancer had already invaded her spleen, heart, and lungs. I took her to the emergency vet early on a Sunday morning because she was pacing and panting. After lots of inconclusive lab work the abdominal ultrasound showed all the tumors. Her heart was failing and she was beginning to bleed internally. She was 11.
My weim, Hannah, was diagnosed early in her illness. She went in for a chest x-ray due to her history of heart problems (murmur) to see if her heart was enlarged. It wasn't, but the x-ray clearly showed a small tumor in one lung. Followup with the specialist revealed involvement of her spleen, heart, and one lung. They gave her 4 to 6 weeks, but she fooled everyone and lived another year before her heart gave out.
You and Beth will be in my thoughts.