you WILL KNOW if your cat is in heat, belive me. before i had my female spayed, she was very annoying, and i love her with all my heart. she would roll around the floor constantly. some cats will meow constantly, that is what my friends cat does. also, i noticed a clear discharge from my cat. (i don't mean to sound disgusting, she just put her butt up in the air and i noticed it, believe me, i could have done without her show.