It may sound strange, but dogs can develop this disorder. It is NOT the same as what humans develop, but if a dog misses two or more meals, this could very well be the cause.
It is very important to watch your dog and make sure when you feed him/her meals, they eat it with vigor and are excited and hungry each time they are ready to eat.
Sometimes a dog will miss one meal, if they do, you know they are a bit under the weather, two or more meals means there is something definitely wrong and a vet visit is mandatory. Your dog could have a blockage, be seriously ill or in severe pain, which are reasons they may not be eating their meals.
If you would like more information on dog anorexia, there is an article that will explain this disorder in depth.