At what age do cats/kittens go into heat? Since finding Roxy and determining she is about 6-7 months I'm not sure if she was already in heat or if she maybe going at any time now? She goes back to the vets for a re-check tonight on her wounds and we are hoping to get her spayed within the next couple of weeks. Where she was stray and the not knowing her history we obviously don't know if she has had any shots so she needs to get up to date before they spay her. I know about dogs cycles but never owned a kitten this old that was never fixed so I am curious. Thanks guys