The perfect nutrition diet for a dog divers by the breed and where they live. A dog that lives outside where there are harsh winters need to have foods with a good amount carbohydrates and proteins. Since these dogs burn the excess fat, it will not harm there health. Sheephearding dogs requires a large amount of carbohydrates and proteins to keep there energy high. Also, a supplement of calcium isin't a bad idea for this breed to protect the bones from all the extreem running speed they do. Giving a slice of bread once or twice a week actually helps to clean a dog's teeth and no, it dosen't harm there health, the fiber the bread contains will do them some good a believe me it works. My old Siberian Husky was 13 and the vets gave him 3 because he had clean teeth.