re: Pet gate?

How about a teeter totter, weight based kinda portal thing. Cat go/ dog no go.

Trap door, again, the weight based idea.

Or a force field, set up like key cards at work. 

Concertina wire is effective. Cats will get through.

Armed guard.



I'm probly going to let you down but, I swear I won't keep you down. John Hiatt