The extremely timid feral cat I fed for a few months in my garden came into season so I had her trapped and taken to be spayed. The vet said after opening her up that she had already been spayed, and you could actually see a faint healed line next to the new operation scar. She lives in my flat now - coming and going in and out as she pleases - and is happy as Larry. Two months later I thought she was getting really fat... But she'd been spayed.. Right??? God only knows why the vet missed it... Hey ho must have been meant to be... cats are brilliant :)