Yes, cat flaps are a good idea but they can be a mixed blessing. Obviously, the cat flap gives your cat convenient access to the outdoors. If the cat flap is microchip activated it should prevent other cats coming into your home. If it is not microchip activated then other wandering, outside cats may quite possibly, and probably will, enter your home.
Once this happens, your cat – let’s call him the resident cat – is on the alert. He is on the alert for an intruder trespassing upon his territory. The stranger cat may well eat your cat’s food, use your cat’s litter and anything else that he wishes to do. You may get to know the cat! The resident cat might take umbridge.
Depending upon your cat’s personality the reaction from your cat may be anything between terror or an opportunity for a nasty fight in order to defend his territory.
The intruder may spray urine in your home in order to mark territory to claim it as his own or conversely your cat may do the same thing in order to make the point that the territory is his. The resident cat may become anxious and defecate on your bed. Sounds gross but sometimes anxious or stressed cats do this.
Apparently, in one survey it was found that over 50% of homes with unlocked cat flaps had urine problems as a result of a cat spraying (rather than urinating).
In addition, sometime microchip operated cat flaps do not work perfectly. I’m told (although I have not experienced this) a microchip operated cat flap does not work well if your cat races back through it at speed.
Further, a strong stranger cat may well be able to break through a locked cat flap with brute force. I have to say that my cat who is barely adult broke through my locked cat flap (a quality product) to get to the outside. He was locked in because I was about to take him on a long trip up north. Fortunately he returned in time for me to take him in the car.
Sometimes the only way to deal with cat spraying in your home is to board up the cat flap in a very positive and noticeable way as a visual signal to cats that this thoroughfare to the outside and inside is permanently closed.
There is another issue which I think is worth mentioning. Cat flaps can be a security problem. If the cat flap is in a back door, which is the most typical position for it, and if the homeowner leaves the back door key in the lock on the inside, then a burglar has access to the key and could use it to open the back door. Even if the key is not in the back door but somewhere near it, the burglar still has access to it by using a long stick or device of some sort.
In conclusion, cat flaps are undoubtedly a good idea. They are used worldwide in their many millions with great success. There just happens to be some downsides as mentioned above.
Do you have any stories to tell about the benefits and mishaps concerning the use of cat flaps which I believe are called “cat doors” in America?