Question.

We have a geriatric male cat that has been cut 10 years and started peeing. Not everywhere so not an issue of incontinence; rather specifically in our bedroom in front of the closet. We resolved the issue this way:
1) vet check and antibiotic injection. Blood tests showed no crystals, but his temp was up.
2) used one of the enzyme pee removers on the carpet and cleaned the carpet.
3) used a black light to confirm to 'splatter spots' we might have missed.
4) took a piece of cardboard and laid it over the preferred area for one month and put my shoes on it to weight it down and keep it in place.

We agreed in advance, that if this didn't work, he would have to be put down. There is no option for putting him outside after 13 years of being an indoor cat. To his benefit, these steps worked and he stopped peeing outside the litter box. The other two males also did not try to 'remark' the same location.

__________________
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~Eleanor Roosevelt

First of all, I'd shampoo the carpet (where he has already peed with a solution of equal amounts of white vinegar and hydrogen peroxide with a quirt of Dawn. Then I'd rinse with clear water and more vinegar. Then regularly spray with plain white vinegarevery day.

We have an old male (neutered) in the house and he will spray by the outside doors expecially if he smells another tom outside. We regularly spray both side of the doors.