I just read the description on that web site, entirelypets. By the sounds of it, you do not want to put it in the room(s) with litter boxes. It says the cat will not soil anywhere near the Feliway.

I have been considering getting some for Sparkle, she gets very car sick. We are traveling 3 and 4 times a month just now. Yes, family trips, all SEVEN cats. She is the only one with motion sickness. For now, vet said to try dramamine, and work our way up to Feliway if that doesn't work.

Good luck with Oscar!