Dogs and pregnancies

I know pets can sense when you're pregnant but did your dog behave odd before you found out? With my last pregnancy my 2 dogs didn't acknowledge anything to do with the baby till I had already found out I was pregnant and was about 3 months along. My fiance's dog has been all over me the past few days more than usual. Over the last few weeks I have taken multiple pregnancy tests all have come up negative but during my ovulation I had pink spotting for 3 days, I haven't tested this month yet.