Our next step is to install a cat door through the garage wall, so that the cats can access it by themselves.
Last night at 4 am, I was awoken as I heard something crash into the cage and cats were flying in the cat door and around the house. I looked out and a young cougar was hanging on the cage. The cats were saved by the den. I was shocked that it stood up to the force of the big cat, but thankfully it did. I live on Vancouver Island and although the big cats are not seen during the day, they are out at night to hunt.