Many dogs don’t miss a trick, especially when it comes to behavior repeated right in front of them. That’s how we inadvertently teach them the very dangerous habit of opening doors.
Lever-style and bar handle mechanisms make it easiest for dogs, since opening the door requires them to only hook their paw or mouth and press in a single direction to open the door. In contrast, round knobs require a turn and pull with an opposable thumb, which is an exclusively human ability.
If replacing hardware isn’t an option, child-proof mechanisms can prevent dogs from using lever-type handles. Child-proof locks also work to keep dogs out of cabinets and refrigerators.
Instead of frustrating your dog once he’s perfected the habit, try to dog-proof doors ahead of time.