Jon Freeman, if your stray tom is still quite young, the broadening of the chops that identifies a tom cat is still a ways off, as we say in Ontario. Our Watson was neutered very young -- between four and five months, if I recall correctly -- and he was indistinguishable from his sister Isobel until they were both more than two years old. Now that they are almost five years old, Watson is half again Isobel's size and weight, and sports the typical broad face of a full-blown tom. God alone knows what he would have looked like had he not experienced that special trip to the vet!