My female dog is in heat. She has never had a liter or sex for that matter. I was inspecting her teats and they are bigger but not swollen, red or have any bumps whatsoever. She does however have clear brown fluid come out when I squeeze her nipples. I've tried looking online but they all say mastitis or cancer but other than the fluid, her teats are normal. Now I am worried sick. Can someone explain or help please.