My dog wont eat

Question
I have a 9 yr old black lab mix named Dakota. He hasn't eaten in a week. I think I know why. We have a cabin about an hour from our home. We go there on the weekends. There are some new dogs down the road from us at the cabin that just moved in. He has been going down there a lot. He even spent the night outside there house one night. When we went home he started acting strange. He wont eat, he lets out quiet faint cries, and he's even howling. He has never howled before. The next weekend we went back to the cabin and now I have him on a cable so he cant go down. He keeps trying to go in that direction. How can I get him over this and back to eating again?

Answer
If he hasn't eaten in a week, he really needs to see a vet to determine why.  I have never had a dog starve itself especially when there is a food bowl next to him.  Something is wrong!!!  Another thought is that when he is visiting the other dogs, he may be eating their food.  Is he losing weight?