Just a little personal note with personal experience with our own dogs.
The first was about 1992, before ultrasound was available. Our 10 yr old Golden had an abdominal mass I felt then confirmed on X-ray. I did an exploratory and removed a large liver tumor, benign. But, she had Addison's and that complicates recovery and resistance to infection. She recovered but died three months later from an overwhelming infection. This was before many of the amazing antibiotics that are now available.
The second was just a few years ago. Some of you met Kaiya at an Old Fella rally in Ohio. She developed confusing symptoms while we were on this trip. When we got home, we found an abdominal tumor and ultrasound showed spleen and liver involved. Her spleen had ruptured. I did a surgery and removed the spleen, but she didn't recover from the surgery.
Probably not the best stories to share because neither turned out well. I've also had dozens that did turn out well.
I just wanted to share and let you know we understand what you are going through from both professional and personal perspectives.