Our Gender Bender Cat

My wife and I bought a cat at a nearby pet shop. He was a neutered male. And we love him very much. One day I was doing tickly tummy which he loves and noticed something was amiss. Our little guy looks more like a girl; so we took him, or should I say her to the vet and to our surprise he was a she. We are very fond of our new little girl and still have no man of the house, lol.