I just got a puppy, and my house came with a small dog door when I bought it. He fits through it now, but in 4-5 months, I will likely have to replace it with a larger dog door. A lot of what I'm looking at seem pretty flimsy, and the covers are often plastic. I remember when I was little, I could fit through the dog door at my parents' house for a while when I was 10-12 years old, and worry about skinny burglars in my neighborhood doing the same. What's a good anti-burglar dog door in the medium/large size range?