My son adopted the best cat ever from our local shelter. Sadly he has had some health issues and was underweight. He has never peed outside the litterbox in all nearly 3 years we've had him (he is almost 5yrs old now). He was getting frequent uti's and bleeding allover, straining to pee, crying in pain, laying in the bathtub for the coolness. We took him to the vet (cha ching $$$$$) she put him on a special diet (more $$$$). he ended up getting the uti again, and I found this site, tried the emergency apple cider vinegar method using organic ACV with mother, then every few hours...with a couple days healed!
This was over a year ago, he has not had another uti since and is eating quality food we buy locally, with is way more affordable than the what the vet sells. I highly recommend ACV. I thought it was worth a try before running to the vet$$.