I had a dog with splenic hemangioma. It was very difficult. She was 10 years old and became ill very suddenly. The ER vet did the Xrays and ultrasound and told us there was a very large mass in the spleen. We were told it was frequently cancer. My little dog was at the point of the organ rupturing (pale gums, the spleen was "seeping"). We did the surgery and it bought us an extra year with our girl. Biopsies didn't show cancer, but the entire organ wasn't examined. This is a brutal surgery. Removing the spleen causes something to happen with the cardiac enzymes. Tipper, my little Scottie, was in ICU care for several days to monitor her heart, which was causing problems. We did the surgery because it was either that or put her to sleep. She was critical at the time. I know another Scottie owner who's dog died in recovery from the heart complications.
I know you have opted not to do surgery. I just wanted you to know that the recovery, if the dog survives surgery is very hard. My little dog took weeks to get her strength back and then without her spleen, her immune system broke down and she had random, bizarre infections her last year (UTIs constantly, hepatitis, etc.)
Tipper was a pudgy little Scottie at around 28-30 pounds. When she had her surgery, the spleen was the size of a 16-20 ounce soda bottle--it weighed over a pound. It was so engorged, it was pressing on other organs and she wasn't comfortable. I was told that her condition was one that was indicative of trauma, but she was a pampered little house dog, so no trauma. We don't know what caused this, but it is devastating.
Make your decisions for Ragg's best interest and please don't second-guess yourself. It is a horrible surgery. Tipper did get cancer later on. Chemo treatments for my Tipper's bladder cancer destroyed her kidneys and she died from kidney failure. As one who tried the chemo route, I have to say I wish I hadn't done this part.
I'm so sorry for this diagnosis. It is so hard. I will keep Raggs in my prayers and ask for strength for you as well.
It is hard for me to talk about this. I miss my little Tipper so much still.