abdominal mass

Question
I took my 2 1/2 year old boy in this morning to get his back foot looked at, he has a bumble and I've been concerned about infection.  Long story short - in the midst of her examination, the vet said his abdomen didn't feel quite right, and while the boy's chunky she didn't think she was just feeling a fat tummy.  An x-ray showed a large mass. I can't even begin to imagine how long it's been there, growing.  At the moment, it is not pressing against his heart or lungs, and the vet said they actually sound pretty good for an old timer.  The size of the mass prevented her from determining what it was growing off of. However, she felt that at 31 months of age, my old guy was not a good surgery candidate.  At the time, I was inclined to agree, and asked what now?  She said as long as he appears to be comfortable and is eating/drinking/pooping/etc normally, then there's nothing to be done. Her only concern was if the mass begins to press against his intestines, hence her instructions to keep a watchful eye on whether or not he is passing stools.

Now, I am wondering.  Is age alone enough of a reason to rule out surgery? A couple of months ago he had sudden loss of function in his back legs, and no x-ray was done because everyone sort of agreed that it was a result of trauma.  He got some function back with steroids.  The vet now says she doubts this mass could have been the cause of that, but we'll never know.  But aside from the weak hind limbs and this bumble, my boy has been in good shape.  He's slowed down over the past month, but again, I don't know if that's from age, or from this mass inside of him.  But if the past month is any indication of how quickly this mass is going to end thigns for him, then I predict he has very little time left.  Do you think there's anything to lose by asking the vet to try surgery?  Worst that happens is he doesn't make it through.  But my instinct tells me with this mass in him, he won't be around much longer anyway.  What do you think?

Answer
I have had rats survive surgery at 3 years of age and even older.

You are right, with the mass in there, it can take his life at any time. On the other hand, how experienced is the vet?  

Just recently, someone wrote to me that took her young rat for a spay. The vet, who claimed to have alot of experience with rats, removed the rats kidneys rather then the ovaries and the rat died three days post op. Necropsy by another vet revealed the mistake.  The vet that did the surgery claimed he could not really tell the difference between the ovaries and kidneys since they were diseased and there was alot of physical changes going on.  To the owner of the rat, this was a poor excuse. Her young rat was dead due to error on his part.  Sad but true, its very important to be sure that your vet is qualified to operate on your rat. I would opt for a second opinion and also,you can go private and let me know the name of your current vet. If you want I can check her credentials for you.  Dont be fooled by a vet that says they know exotics. If they dont have experience, and I mean ALOT OF IT, this increases the risk to your rat.