I've been having a problem lately with 1 or 2 specific male cats in the neighbourhood coming in to my house via my cat flap and scent marking/urinating on vertical surfaces to (I presume) mark 'their' territory.

My 3 cats seem to tolerate the main culprits, I wouldn't say they are "best friends" but they do hang out harmoiously out the back!

I don't want the scent marking to happen any more because the smell is really noticeable and disgusting. (the cats don't seem bothered or avoid those areas or anything, though).

Please can you give ideas of how I can stop these guys from doing this?

Edited to add: every couple of days I clean off any existing 'deposits' using disinfectant etc. I bought a UV light to show up where any specific 'deposits' are!

Edit 2: I'm particularly looking for ways that even if a 'stranger' does somehow get in the house.. how to get them to "not" scent mark, rather than how to stop them getting in, if possible, please.

  • Note: Marking is a behavior primarily for unfixed toms. Assuming these are strays, you may want to capture them to be fixed (there are usually local groups that do this for free or a very low price, your local Humane Society may do it, or know the groups that do) and either adopted or released; if they're not strays, hoo boy, that's one irresponsible owner, we don't need more stray cats in the world from their toms knocking up every unfixed female cat in the area. Commented Apr 14 at 14:02

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You can get battery-operated, electronic cat-flaps that will only unlock if they detect recognised microchips. This is a convenient method to control access if your cats have been microchipped.

The SureFlap is one such cat flap. We have one, and it works as advertised. You can also get tags with a built-in microchip that can be attached to a collar, but having your pet(s) microchipped is the better solution. The SureFlap is supplied with one such tag, iirc. The SureFlap has a timer to deny entry and/or exit if you want to curfew your cats. It will also allow unknown cats that have managed to gain access to your premises to exit at any time.

  • 1
    I concluded after a lot of attempts that there isn't really a way to discourage cats from scent marking if they are determined to! As of a couple of days ago I'm now the owner of a "smart" SureFlap (which has a hub and an app that goes with it showing how long the cats have been outside etc) and so far it seems to be working. NB: I'm not a "shill" for the company (check my posting history). I'm just a happy customer! Commented Aug 13, 2019 at 19:43

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