Dogs shouldn't eat cat food; it's formulated with a lot of fats that may be too rich for the dog's digestive system.
To tempt your dog into eating his own food, start him out on a diet of boiled hamburger and rice. It will fill him up without upsetting his tummy.
Then slowly, over several days, start adding some high-quality kibble to the rice mixture. Each day, add more and more kibble while at the same time you are decreasing the amount the rice and hamburger. Eventually the dog will get to the point where he's eating his normal food. As an extra treat, you can also pour beef or chicken broth over the kibble to give it extra flavor and soften it up a bit.
Feed your dog only at specific times during the day (don't leave food out all day). If he doesn't eat his breakfast, don't give him anything to eat until its supper time. If he doesn't eat his supper, don't feed him anything until breakfast... He won't allow himself to starve, and will learn to eat what you feed him when you feed it to him.
Check to make sure you're getting a brand of dog food that is not on the MenuFoods recall list. Someone here recommended Old Roy rice-based dog food. That food is on the recall list for being contaminated with rat poison and melamin.