Shadow came back home from the vet today. Basically, we agreed to let him stay there in order for the biopsy to be done. But to do that, surgery had to be preformed on him.
They took a sample from inside his body, likely from the unusual growth between his spleen and liver, and are planning to have it be put in a lab where it can be tested. That way, they can have answers as to what exactly this growth actually is. As far as we know, it might be tumor, or it might not be.
But because Shadow is a golden retriever, there is a high chance that it's cancer. But we don't really know. We won't get any answers until either Monday or Tuesday, as the lab isn't in service during the weekends.
As for how Shadow is doing now, he has finally come home today. He's just recovering from the surgery he had yesterday, and he was behaving rather weak and tired. He was also rather lacking in the desire to eat anything. We did menage to get him to eat his food, including some pain-killers. But we're still deeply concerned for him.
Right now he is resting in the living room. He seems to be alright, but we're still keeping an eye on him.
That's pretty much all that's happened as of today. If anything else happens, I'll possibly update.