We have a 5' wood fence and buried boards all the way around the bottom.
We try to not leave them unattended. Also it's a good idea to check that the gates are closed. My neighbor called me, saying our dog was in our back yard. I put the phone down, ran to see, the gate was open, the dog was nowhere to be seen, I closed the gate, got back on the phone telling my neighbor I don't see the dog in his yard. I turned around and he was standing right behind me. He snuck back inside!
Ours too can open the sliding glass door, but will not close it behind her!
Our male saw a squirrel outside once and just lowered his head, charged full steam at the sliding screen door and blew it out of its tracks! Went right through it.
Also we think of our house as a submarine, with air locks, in that we close all doors behind us, while looking out for the dogs.