Don't start shutting them in without a litter tray, they are liable to start using the house instead and this can become a very difficult habit to then break. Have a look for a microchip cat flap instead. It will only read the microchips of your own cats and keep all others out. Pricey but worthwhile for situations like this by the sounds of it.
We have a microchip one and it is totally fab. It is a sureflap - runs on batteries. I could've paid for it ten times over with the number of collars and magnets I've had to replace. Plus a neighbouring Siamese could work out how to get in by using their claw to hook the little tab. It was really easy to fit and programme. We bought it rather than the pet porte one because it was cheaper.
yes, my petporte was a waste of time as the intruder worked out how to open it wit her head....she then worked out how to get in via kitchen window....talk about persistent sureflap is brilliant and has worked perfectly for a year now and on the same batteries! my only gripe is it could be bigger, but they are app bringing a bigger model out next year
Another vote here for the Sureflap. We had ours fitted yesterday and no more gatecrashing cats - bliss!! One tip, put it on learn mode when you're around and get your cats through there ASAP. Otherwise sod's law will dictate that Ginger will also have a microchip, will nip through when you're not looking and you'll wonder how he's still getting in. And it will be back to square one...
We have this same problem. We get multiple cats coming in, eating all our cats food, and last week the neighbours cat worked out it can even get in our fridge! It got a chicken that MIL had brought round for DD as she was ill and refusing everything but chicken. We've spent the last week with a door stop and DD's high chair up against the fridge. Today we got a fridge lock.
Unfortunately our cat flap is in the glass of the patio door, so a new cat flap would mean a new glass panel too.
Tonight I chased neighbours cat out. 20 seconds later, she was back in. Cat flap is now locked.
Annoyingly our cats are big old brutes, they aren't scared, but they can't be bothered protecting their territory.... but they have started spraying in certain parts of the house.
bilblio, I've got the Sureflap instruction manual here and it says that it's ideal to fit in glass doors - you may need an adaptor piece though. My builder managed to remove our existing cat flap and replace the new one fairly easiy. Just a thought.... I can always send you the page of the manual if any help.
Cambridgeferret is right, you might not need to replace the glass panel, provided the SureFlap Microchip Cat Flap can fit in the hole left by your existing cat flap. What you could do is take out your existing cat flap and measure the hole. If the hole is between 210mm and 260mm then the SureFlap will fit! You would need to purchase the SureFlap mounting adaptor as cambridgeferret mentioned. For more details, please visit: http://www.sureflap.co.uk/products/details/2-mounting-adaptor
Ooh thankyou cambridgeferret, and SureFlap. I'll have to work out how the cat flap is fastened onto the glass, and start saving up. Our cats aren't microchipped so it's a big expense. But we'd save a fortune on the cat food bill in the long run.