[crazy4cats]

Hi-
Yes, I’ve heard of d-mannose. I think of it more as more of a preventative, not a cure for an existing infection. I’ve heard a few others mention on this site that they use it. If it is an infection, you don’t want to mess around. They start holding their pee because it hurts. Then that makes things much worse.
Your kitty peeing outside of the box could be a behavioral or territorial act as well. I hope you get to the bottom of it. Cat pee smell isn’t very pleasant!