It would be a very good idea to review ingredients of the food(s) you are feeding your dog and if the content or rice is substantial, switch to a food that has less rice or has none at all.
It seems that feeding a dog a healthy and affordable diet is getting increasingly difficult in spite of the multitude of choices available these days. There are so many things to consider, and "experts" often provide contradictory advice.
We are active breeders and since it has been proved that too much calcium in a female's diet leads to whelping problems we try to stick to the foods that have no more than 1.5% calcium. There are other factors to consider as mentioned in this article http://jn.nutrition.org/
Just a couple of weeks ago this interesting study reported that less protein and more fat in the dogs' diet helped trained dogs perform better in exercise and detection tests. During an 18-month period, researchers rotated 17 trained dogs through three diets: a high-end performance diet, regular adult dog food, and regular adult dog food diluted with corn oil. It was found that dogs eating the normal diet enhanced with corn oil returned to normal body temperatures most quickly after exercise and were better able to detect smokeless powder, ammonia nitrate and TNT.
Disclaimer: Remember that we are not experts in canine nutrition.