The little guy is going into surgery Monday. It is very sad but at the same time, that guy has been on borrowed time since May where he had the most shockingly fast acting pneumonia or whatever the heck it was I have ever seen.
In a matter of less than 6 hours he went from perfectly fine to unable to take more than a few steps before laying down lethargic and what, to me, looked exactly like agonal breathing (the mechanical breathing that happens just before death during euthanasia) with a wet clicking sound. I was in shock and certain he would not make it to the vet ER alive. More than 1h in the oxygen tank only perked him up for a few minutes. 48 hours later with little more than Baytril and hand feeding of ensure and oatmeal and he was running and jumping OVER stuff instead of going around them and his regular vet could see nothing wrong with him. You don't get miracles often with rats, I consider that one to be one of the few we get.
I am a little encouraged that the mass is very mobile and appears well encapsulated with only a tiny strand is attached to something else (as opposed to something weirdly shaped or intertwined with many other parts of the body). What it is attached to, however, is the big question. The location is also particularly dangerous for a mass. If it's linked to an organ or some big blood vessels, it's probably going to be very difficult to get it all or out at all. If it's muscle, then maybe all of it could come out.
Even if this only buys him a few more months of mobility and quality of life, I think it's worth it. He's the most energetic of the trio and has ample ahem ... fat reserves shall we say ... to carry him through not eating a lot after surgery.
So keeping my fingers crossed while keeping in mind the reality that these guys have crummy genes, got a horrible start to life and essentially the odds stacked against them. That they turned into such trusting, sociable and friendly rats despite that is a massive blessing.