Microchip cat flap

A microchip cat flap is a pet door with a built-in reader. It detects the radio signal from the microchip already implanted in the cat and compares the number with those stored in its memory. If it matches, the flap unlocks. If not, it stays shut, which keeps out neighbourhood cats, foxes and raccoons.

You teach the flap by putting it in a learning mode and passing the cat through. Most models can store several cats, and many can be set to lock at night or to allow entry but not exit, which helps if a cat has to be kept in before a vet visit. Some versions read a collar tag or a magnet key as well. Battery life varies, so replace the batteries on schedule and keep a plan for the days it fails.

Keep the contact details on the chip registry up to date, so a lost cat can be traced back to you. A flap is not a replacement for supervision or a catio if you want to keep a cat out of roads, and a breakaway collar with a tag can still be useful.