If your doggie door is big enough to allow an extra-large breed such as a St. Bernard, Labrador retriever, or Great Dane easy access to both the house and the yard, chances are it's big enough for a human to crawl through. And there are some humans who would happily crawl into your doggie door and crawl out again with your laptop, the silver, and any credit cards you may have left lying around.
It is possible to burglar-proof your large dog door. Surprisingly, the best solution is not the most obvious.
Don't switch to an electronic door. An electronic dog door requires your pet to wear a transmitter on her collar that communicates with a receiver at the door, ensuring the door will only open to an animal wearing the transmitter. This type of dog door is ideal for people who have a cat they'd like to keep inside and/or raccoons in the neighborhood they'd like to keep outside. Since they're designed to deter beings that weigh less than forty pounds, electronic dog doors are made of one layer of plastic. As sturdy as this plastic door may seem to be, it will not last long against a determined human with a hammer or a box knife.
Lock the door. A far better deterrent for door-crossing burglars is an old-fashioned lock and key. If your dog door is big enough to allow human passage (no matter how awkward), your dog is probably big enough to be able to push out a solid wood door thick enough to hold a deadbolt lock, if necessary. Whenever you're away, simply lock the dog door just as you would your front door. Or leave the dog door open and make sure to install---and use---burglarproof locks on your yard fence gates. Security consultants agree that a dog is already an excellent burglar deterrent device, especially one that barks at the sight of a stranger.
Consider installing a door with security features. Many models of pet doors come with locking features, metal security panels, or are designed to just barely flap open enough to let your pet in or out---and a bulkier human may not fit. These doors may cost $200 or more, but they are definitely burglar deterrents.
Add other security features. Even if your dog is the sweetest boy in the world who has never met a stranger, consider putting a "Beware of Dog" sign in your window. Even burglars won't go someplace where they might be bitten.
Eliminate the doggie door entirely. If you still aren't comfortable with the security---or lack thereof---in your dog door, consider removing it, or replacing your door with a hole in it with an intact door, and teaching your dog to let you know when he wants to go out or come in. After all, if there's not dog door for a burglary to crawl through, your house is that much more secure.