I once had taken a feral female cat from the barn and had her spayed. Ended up that she had an infection and had to be confined for a few days post-op. So I created a "run" that attached to a rather large carrier so that she could walk around while she recovered. Anyway, her first night in the spare room, in this set up, she escaped. I had the two pieces tied together with rope and then bungie cords. There was just no way she could get out. Guess what. I heard a crash (the plywood blocking the door to the room) and went in to the living room only to find my poor old cat sleeping away on the sofa and this wild and woolly, feral cat, wandering around the house. When she saw me she tried to jump through a mirror I had on the wall. She was in a real panic. Eventually I opened the door to the screened in porch and that is where she lived for several days and then I let her free. It was horrible to see her so upset. She must have used every ounce of energy she had to squeeze between the ropes and cords. She was slight of build but feral and mighty strong! She survived the operation but disappeared from the group of ferals shortly there after.