Will a pet door let cold air, bugs, or intruders in?

Triple-flap, magnetic-seal, and motorized airtight designs perform far better than single vinyl flaps in cold climates, according to community threads we read. Reviewers consistently flag that even the best passive flaps can get pushed ajar in high winds or by determined dogs, and that any pet door is a security trade-off, most owners add a locking slide-in panel for nights and travel.