We had an orange neutered male cat we took to the vet one time, in a nice cardboard kitty carrier. He was not a happy camper. I kept watching him on the back seat- he did some mewling and angry scratching, and then his pink nose was snuffling at one of the larger air holes. Then a fang appeared at the hole. It wiggled and jerked. Then two fangs. The sound of tearing cardboard. Then the fangs got larger. And larger, he was ripping the hole out, cardboard shredding, his muzzle appeared, more cardboard shredding everywhere, it was like a scene from a horror movie. He got his whole face out and when he got most of the side of the carrier demolished he climbed out, and spent the rest of the trip on the seat, amidst the tattered shreds. “I’ll show YOU who’s boss…” . It all took a matter of minutes. We never wasted money on a cardboard carrier again- plastic and metal from now on.