My 3 year old neutered male has chronic uti and crystal issues. I've started him on Rx dry food, and plan to try the apple cider vinegar. I'm also thinking about trying cranberry juice concentrate (available at health food stores), mixed with no sodium or low sodium chicken broth. I brought home a package of Kittles brand cranberry and chicken treats, and my Sammy begs for them. I had no idea cats would love cranberry flavor! If I can find a low sugar cranberry juice, I'll try that. If Sammy accepts this remedy, I'll probably use an ice cube tray to prepare a whole batch at a time, and stash them in a freezer ziplock bag. So much easier to just thaw a cube whenever I need it. Good luck to all, and hope your kitties are much better!