It appears cat have been wreaking havok for clay workers for at least a couple of millenia! Paw prints were found on 2000-year old Roman roof tiles, perhaps made when the tiles were laid out to dry. The tile was fired and used nevertheless - for all we know the marks were considered an embellishment! That wasn't the way of it when my own feline friends - kittens at the time - contributed to my work, but who knows? More likely, it just didn't matter, as the fairly shallow prints didn't interfere with the function of the tile.