I have 3 cats outside that my daughter and granddaughter's insisted had to move with us. (Other's stayed with our old neighbors to kill their mice and snakes.) The 3 cats didn't do any damage at all the the catnip in the ground.
I brought a variety of herbs and other perenials in pots in the house for the winter that I just had sitting outdoors all summer not knowing where I wanted to plant them. And lo and behold in a medium sized pot of English lavander here comes a little seedling of catnip. It's got several 6 to 8" plants in it now. I'm just letting them grow together for the winter.