Dog in Heat?

I just adopted a dog for the first time ever yesterday. I've always had cats so I'm kind of new to this. She is a 3 year old dachshund/jack russell terrier mix. When I got her she was in heat and she still is now. We were suppose to get a free bag of dog food when i got her and they didn't even say anything about it. So for the first night I gave her Purina Alpo Prime Cuts(wet food). It was all we had at the time and she ate it just fine. She isn't potty trained so I would rather her eat dry food so if she does accidently go to the bathroom it won't be such a mess to clean up. So today I tried to give her The Good Life Recipe(dry food) and she won't eat it. She hasn't ate since yesterday. Anyone have any ideas or info. on why she's not eating it?