How to keep the neighbour's cat out of my home with a cat door?

Question

I installed a cat flap on our door for our cat Pablo, so he can leave the house to socialize with the other outdoor cats in the neighbourhood. We didn't have any problem until one of the other cats (Karel) figured out how to use our cat door. Karel started visiting us quite frequently, mostly for stealing Pablo's food, or sleeping in our bed while we're away from home, but it also happened that he peed on our couch. Pablo is quite frustrated every time Karel enters his territory, but doesn't care enough to scare him away. I tried to scare Karel away by making loud noises, by chasing him, squirting water on him, but nothing worked so far, he still keeps coming back.

I was looking for methods to scare a cat away, but all of the solutions I could find like the infra sound emitting motion detectors and the pheromone sprays or powders would also scare our own cat away.

We talked to Karel's owner, but she is not willing to lock her cat up.

Answer 1

As your cat Pablo has a chip, he always carries a unique method of identification. I would suggest you swap your current cat flap for one that reads microchips and opens up just for your cat. Yes, they are not exactly cheap, especially if you have a perfectly fine regular flap, but it should pay for itself over time in cat food, cleaning bills and a happier Pablo.

Answer 2

The high-tech version is to use a camera, machine learning, and a solenoid to lock/unlock the catflap. Ben Hamm had a video about a system like that, although his problem was not detecting a particular cat, but to determine if Metric had an unwanted "gift" or not.

Probably this is more expensive than a chip reader, but you learn more by building it.

Answer 3

Our friends have a cat flap that is magnetic. Their cats have small magnets on their collars that open the cat flap and also trigger their food dishes (which are covered with a motorized cover).

Of course they always leave the door open anyway and the dogs scare away anything that comes in, but still, the magnets seem to work pretty well.

Answer 4

You could always close up or get rid of the cat flap. Cats can be pretty smart and patient about knowing when they can expect to be able to go in and out, sometimes even meoiwing at a window after hours if needed. They're good at sleeping in the bushes by the door, waking up when someone comes who can let them in. Worst case the poor dear is stuck out all night, but that won't hurt them (not even emotionally).

At first your cat may be terrified, clawing pitifully at the non-working flap, but it won't last long. After a few tries, maybe with you standing outside and the door closed, it will figure out that if it waits, a human will let it in eventually.

Not being able to flee through the cat door to safety might seem dangerous, but if your cat is already going more than 50 feet from your door, it's in the maximum amount of danger (from dogs or coyotes or just cars), flap or not.

Answer 5

If you have a hallway or porch, you could close the next door and make it difficult for cats to open.

That way you can at least limit how far the neighbour's cat can come, and your own cat can still get some shelter until you come around and let it in.

Answer 6

I've trained cats... using water is effective when they have zero training. Eventually you can just use verbal commands tho. Anyhow:

1. Keep the cat door locked when you're not home until this issue is resolved.
2. Get a water gun. Every single time you see that neighbor's cat entering or in your home, blast it in the face with water. It'll run back home. Eventually it will learn not to come into your home at all. At that point...
3. You can leave the door unlocked when you're not home.

That said, I'd expect that cat to try the door again after maybe 1 month. Repeat step #2 then. Then it will probably vanish for say 6-8 months. Repeat step #2 again. At that point it won't happen again.