I found my 110 lbs. Lab um...attempting with my 5lbs. cat. She is due for her spay next week. She is approximately 7 months old. She has never been in heat before and I have never had a cat in heat before. There are no male cats and she is not allowed out of the house at any time. Is it possible that he can sense she is in heat? Marley is neutered, but wasn't neutered until 3 years, I'm not sure if he was used for breeding purposes. I can't get the image out of my head and I can no longer look either of them in the eye.