More and more, I'm being called to repair damage done by burglars. Robbers are breaking into homes with the doggy door systems that install in sliding glass door systems. They simply push on the doggy door until they can reach in and unlock the sliding glass door. Not to mention that number of these doors are not installed correctly, making it easy to break in.
Be safe. Install the right type of doggy door. Sometimes that is not the easiest door to install, but it is the safest. Also, be sure that you lock your doors and windows. Especially those in the back of the house where a would-be robber can break in undetected by neighbors or passers by.