The first thing to do if your dog is not eating is consult your veterinarian for possible illnesses. There are many illnesses that can lead to not eating, but there are also many behavioral causes as well. Once you've ruled out illness, you can become a little more strict with your dog's eating habits.
Health Problems
Your dog's reluctance to eat dry food may have to do with illness. Sometimes, dry food isn't enticing enough to interest a dog with digestion problems. Dry food can even make a stomach upset worse, which is why many veterinarians recommend a more bland diet when your dog is vomiting or has diarrhea.
As your dog gets older, he may suffer from loss of senses. A loss of smell can sometimes make dogs more reluctant to eat dry food because it doesn't have a strong enough scent. This can sometimes be remedied by putting hot water over the food and breaking it open a little.
If the behavior has arisen suddenly, it could very well be a health issue, so consult your veterinarian.
Anxiety
Your dog may be avoiding food because of nerves. If you have recently traveled, moved or changed your dog's environment in some way, he may not be eating dry food because he has anxiety about the new situation. This will usually go away after your dog adjusts to his new schedule, so just be patient.
To reduce your dog's anxiety, try to set a consistent routine. Feed and walk your dog at the same time, trying to maintain a schedule as close to his previous schedule as possible. If you're feeding him around other dogs, try moving the food to another room and preventing the other dogs from entering, to make the eating room feel safe.
Play a game with your dog to get him excited about eating or hand feed for a few days while your dog adjusts to the changes in his life.
Food Change
If you have recently changed your dog's food, he simply may not like the new brand. It might have a different ingredient that your dog can't stomach or it may be that the new food makes him feel sick.
Dog stomachs are not like ours. To protect against poisonous food, a dog's stomach attacks any foreign ingredients to keep them from causing illness. When we change our dog's food, the same thing happens. To prevent this, change your dog's food slowly, gradually introducing it during a period of several weeks rather than all at once.
Picky Behavior
Many owners describe their dogs as picky eaters. This often happens because owners add enticements to their dog's food. Then, the dog learns that if he doesn't eat, the owner will add wet food or, better yet, human food. Don't get caught in this trap.
If you have ruled out health and nerves, get strict about your dog's diet. A normal dog will not starve himself. Let him skip a couple of meals. Once he eats his own food, reward him with the enticements afterward. Then, it becomes rewarding to eat the kibble instead of avoiding it.