I've had dogs all my life, but I had never heard of this happening until my sister called me two days ago. Her dog has always had issues with the trash can in their kitchen- my sister suspected it was a behavior that carried over from her days as a stray. Anyway, her dog found a cracker box in the garbage that had a plastic lining in it. The box got stuck on her head and she suffocated. I feel terrible for her- it's bad enough when a pet dies but especially heartbreaking when it's something that could have been prevented. I know she would have put the trash can out of reach if she had any idea this might happen.
If you have a dog that sometimes goes digging, take a little extra time to get it out of their reach. When I had a trash digger, I always made sure there weren't any chicken or meat bones, chemicals, etc, that might harm him but I can't say that I ever put much thought into plastic bags.