Sundae had a bladder stone diagnosed when she was around 2. Her only real symptoms were recurrent UTIs. We discussed the options with the vet and it was either a costly surgery (about a thousand dollars Canadian) for a surgery that was high-risk because it was not much performed in my area of Ontario, Canada, or to try to manage her symptomatically and to reassess if we saw her quality of life decline. Because the surgery was high-risk and really costly, we decided that we would try to manage her symptoms for as long as we could maintain her that way. We did the recommended lower calcium diet and also filtered the water for minerals, since apparently some tap water can be high in calcium as well. She was on a course of suppressive antibiotics (Baytril) over a course of years, because she tended to get UTIs when untreated (apparently the stone can irritate/scratch the bladder walls and can give extra space for bacteria to grow as well.) In her case, this worked really well and, although she still had some UTIs where we had to increase the dose of antibiotics for a few weeks, she really never had signs of bladder pain, wheeking when she peed, loss of appetite, sitting hunched, etc. She actually went on like that for over four years, she passed away recently of old age a couple of months short of turning seven. Now bear in mind that I think Sundae was an uncommonly tough guinea pig, she also had a dental abscess that must have been very painful, but she ate through the entire process as much as possible (the only time we had to syringe feed when when the day before surgery, when the abscess suddenly puffed so much that she couldn't open her mouth to pick food up!) She truly was a tough girl, the vet always said she had the heart of a lion in the body of a guinea pig, so this expectant management might not work for everyone. I do think that the 'gold standard' of care is surgery, and had it been more affordable and more routine for my vet, I would probably have gone that route, but all in all fortunately things worked out well for Sundae even without.