I have a Beagle Dachshund mix and we adopted him a couple of months ago, He seemed to be doing great but he would not eat regular dog food. I then started mixing Beniful and mightydog canned food together and he loved it but now its like he is sick of that and won't eat again. I have been mixing things all the time in his dry Beniful food but he picks it out.
What should I do?

Do you take him on a good walk or run before you feed him? That should be done on a daily basis anyway, but I find after a good walk your dog will come back and want to eat after he burns his excess energy.

You could also try boiling a skinless chicken breast, cutting it into very small pieces, and mixing that with his beneful. He will have to eat some of the beneful to get to the chicken bits.

Good luck!

Check the sticky at the top of the page. It has an extensive discussion of the problem.