When they do, their owners are pretty much powerless, bar putting up a few 'lost' signs.
Until now. Because one bright spark has taken to Kickstarter to fund a GPS tracking collar for cats.
Called Pawtrack, it fits like a regular cat collar, but tells you where your moggie is, where they've been, and when. Which should spell an end to sleepless nights worrying about them.
Pawtrack takes a location fix every 10 minutes, and uploads your cat's position either automatically or on demand. It'll give you a notification when your cat arrives home, or you can fire up the app and see where it is at any time.
The built-in accelerometer even knows when your cat is sleeping, resting, or lazing around, and powers Pawtrack down to conserve battery.
The collar won't waste battery at home either. It'll recognise your home wi-fi and only start working when your cat goes out of range. When it comes home, it'll know it's in range, and power down.
You can even track multiple cats at once. And you can travel all over Europe, the USA and Canada with no drop in service. Handy if you're going on holiday, but still want to keep tabs on tabby.