2 year old Yorkie in heat

Question
I have a 2 yr old yorkie who is in heat and my mother has a 4 yr old male. He was very mean to her at first but now that she is in heat he follows up behind her and licks her vulva a lot but has not attempted to mount her at least in front of us. She is on day 11. Is there a possibility that they have mated but we just dont know it. He refuses to leave her side whereas before he would not let her near him.

Answer
Hi Jade

What I would recommend is that you separate them and only allow them together when you can witness a tie.  It will make determining when to expect pups so much easier.  As well, it's a case of the "heart growing fonder".   Too much time together without a tie can cause frustration on both their parts.   

So separate them and bring them together for maybe 15 - 20 minutes a few times a day.  More is not better.

Good luck