Jen, I can truely understand what you are going through. I had a similar experience with Emily, even down to the thought of putting her down (after many months of peeing). It turned out that she had an anti-biotic resistent UTI. The standard amoxicillin didn't even begin to touch it, needless to say I continued to have the problem. Finally after two rounds on Baytril we seem to have fixed the problem. But it took a long time and along of pills to make it work. I hope that you don't have to give either cat back, but it might be worthwhile to get a different anti-biotic or even have them culture a urine sample to see what it is sensitive to.

Good luck...