I don’t but a friend does and she has large dogs, it’s only used during the day when she has to pop out the dogs are in a lockable from the main house and can then pop out for a piddle
The dog Flap should have their own room. As for the security risk, it is a bit risky. I have one fitted into our utility room door. I leave it open for my dog during the day, and at night in the winter, I close it