Hi T.,
It's obvious you do not live on a farm ~ you probably wouldn't have a problem if farm animals were part of your life. That being said, maybe you should just tell her the truth, just by asking this question I can see that not telling the truth isn't an option. You could say the cat is in heat, that her little kitty body is the age when kittens become grown up cats. Use words that may even be above her maturity, appropriate and the right words. For instance, "procreate" etc., but, I wouldn't say that the cat is in heat. I would say it's her season, or she's in season. Kitty cat isn't a kitten anymore, it's her time (or biologically her season) to want to have her own kittens and she is telling us that. But, because there are so many cats out there without nice homes we don't want her to have kittens and that's why we are keeping her inside the house to protect her from what she would naturally do. We choose her to be our pet and not have the responsibilities a mother cat has, because then, she would devote all her time and energy having kitty's instead of being our cat. Tell her more about cats and what they do on farms to keep down mice or rats for the farmers and helps to keep the farm clean from pests. Tell her if you lived on a farm she would have kittens and she would teach them to keep mice away from the other animal's food. My family was here with me watching a National Geographic program on birds and what they do to attract their mates, their rituals were not only hilarious, but beautiful. My 7 year old grandson didn't ask "why" they danced and made the chirping sounds, or why they wanted a mate, perhaps it was because National Geo. does such a good job with the stories concerning life or procreation in our animal kingdom. If my grandson would have asked about the antics the male bird did to attract a mate, I think we would have told him that the birds want to do what we all want. Meet a wonderful mate, build a house or nest, and have little ones, just like mommy and daddy did, or grandma and papa did. I actually am not telling you what to say, it was nice to read that a mom wants to say the right thing. Too much information really doesn't sound like something that would happen. But, for sure, keep an open dialogue with truthful answers to all of her questions. That will serve you well because in just a few years you will want to depend on open lines of communication, and this is the best way to start the dialogue. Good luck T., I'm confident that your daughter will be able to get information concerning these subjects from her mother, instead of her peers.