the evo is fine, it's all highly digestible protein, unlike poor quality foods, and the big advantage is that it is grain free.
dogs evolved as carnivorous animals and their digestive tract is designed to utilize primarily meat and fat, not carbohydrates.
things are different if a dog already suffers from liver disease, and a specialized diet may be necessary, but for that i'd have the dog thoroughly checked by a vet.
another misconception that is still floating around is that a food with a high protein content causes kidney damage. this goes back to research that has been declared as outdated quite some time ago. as long as quality protein is used (which is easily digestible), there is no problem.
EVO is supposed to be ideal for small breeds and those that need extra caloric intake. Because of the high calories it's great for small yorkies (like mine who are really skinny and have trouble putting on weight).
I hope that helps. If you have any other questions, feel free to go ahead and ask my friend any questions you may have
www.mordanna.com/dogfood