https://www.coop.ch/en/household-pet...aner/p/6365830
Unless your cat is still small & in toilet training, you need to find out why he/she is not using the litter box.
And as Meerkat said castration does help to calm down male cats.
My 5 year old female cat, neutered, gets herself stressed whenever change happens in the household, and she shows it by avoiding her litter box.
Turns out that her habits change every time one of us travels away for work for more than a week, whenever small children come to visit, whenever dogs of guests have stayed for more than a couple of days, whenever she has to spend more than a week in the house (eg: particularly heavy snow, or when healing after any operations). Sometimes her brother gets a bit too boisterous in hunting her, and if that goes on for more than a couple of days, we get weeing again.
We've spoken to our vets about it, and they've confimed its a very common occurance, even in younger and healthy cats. Unfortunately the plug in cat calming products don't work in her instance.
She's basically protesting, and unfortunately it's always on a bed, or on a sofa, or on carpet, so we now own an excellent extraction & cleaning machine! She's a right little love bug otherwise, and usually very good with her toileting habits.
What they do is peeing to mark teritory as safe haven or better said - reclaim it, since they feel threatened, and the strongest 'scent tool' they have is their urine.
Also they've been known to pee on bed when owner is gone again as a fortifying move - they have to defend the castle from the intruders and your scent is the strongest in your bed, so they join forces.
It's great that you've figured out when it happens. I'd recommend talking to cat behaviorst to see if there are some tips and tricks you could do to at least mitigate some stress peeing, like what to do when you have guests, or what guests could do, to keep that stress in manageble levels so she doesn't resort to peeing.
Or you could start reading bunch of books written by various behaviorists, I can't recall some case like that and what was the solution that worked from the top of my head in books I've read.
Maybe even a bit od medication when situation could lead to stress could help her to cope better, like 2 days before guests arrive until 2 days when they leave or something like that.
You figuring out when it happens is huge and valuable information, however it seems like your vet wasn't resourceful in ideas how to help your cat about it, so I'd dig further.
Maybe toys where she needs to dig out food, or focused / more playtime with chasing thing on the rod and such in those times could help her cope better.
Or something else.... I think it's worth checking out more though.
About anti urine product - OP - basically what you need is an enzyme cleaner
I use this one for couches and such, since it has a mild scent and is more expensive
https://smile.amazon.de/dp/B00M976S2...QJRK4PZD1QMW0M
And this one on floors and carpets
https://smile.amazon.de/dp/B014H2GT1...4YNK8K00ZTV6R1
Works great for poop and vomit as well... which was/is my use case.
For urine I'd leave it work longer than for those two cases above. I basically spray all spots and come back to clean the first one, so really short time on hard floors, and on carpet I'd do two rounds or so, without much waiting. But for urine I think waiting gives time for enzymes to really work.
Folks on katzenforum.de recommend biodor and/or bactodes but I didn't tried them yet, since I have a ton of mine
Biodor should be availble in CH in some online shop.