I'm not sure there's a solution for this but thought it might be worth asking here just in case anyone has any bright ideas.
We have 2 rescue cats, had them for around 6 years. A girl and a boy. Boy cat is fairly chilled but girl cat is highly strung and gets easily spooked by other cats outside. We have a large garden and a fair few cats come wandering through.
Every now and then, there's an absolute stink of male cat pee around the outside of our cat flap and evidence of wee. I'm fairly sure it's a big male we sometimes have visiting our garden although I've never caught him in the act. I always spray liberally with an enzyme spray but every time it happens, our girl cat becomes very anxious, on high alert and in and out of her litter tray.
Unfortunately the cat flap is not in an ideal position as it leads out on to the side access and so there's not great visibility. I can't see how we can put one anywhere else as we have two sliding patio doors in the lounge and kitchen and no other options.
The only other thing I can think of is to completely block in the back door where the cat flap is (we never use that door anyway) but then we would be without a cat flap.
Any suggestions very gratefully received thank you!