If you are trying to breed Fluffy with one particular male, keep her contained in a room for at least 24 hours with her chosen mate. You should also keep her inside during the rest of her heat cycle to make sure she doesn't seek out additional male attention. Otherwise, the best course of action is to make sure your furry friend is spayed. Her efficient reproductive system can lead to too many kittens. And as the ASPCA notes, many healthy cats are euthanized because there aren't enough homes for them all. If you're concerned about Fluffy's reproductive status, talk to your vet or local humane society about getting her spayed.