That's a good question! No science based links handy to post but I THINK it really comes down to the individual dog, health, age, size and activity level. That's the comment that seems to be a common or most prominent theme of similar questions.
You want something your dog will eat and you want something that has a good balance of nutrition. I personally feel, like humans and other animals, higher proteins and nutritional levels, coupled with activity and exercise, are most important during the growing years. Once a healthy body is created, it's a maintenance issue of nutrition and activity. Some of the nutrition levels could be reduced once an animal is and adult. Again, like humans, if the food is too rich, problems will occur but may be years down the road and not attributed to, linked to, the food they ate.
You might try a search here and the web: nutritional requirements for a healthy yorkshire terrier. |