Protein in Dog Food

Question
I have a 15 month old male Yorkie.  He is 3.5 pounds.  He came to me at 10 months with terrible teeth and foul smelling breath.  He was being fed Royal Canine Yorkie Blend 28 with 28% protien and 18% fat make up.  I had his teeth cleaned and changed his food to Nurto Natural Choice Chicken and Oatmeal with 21% protien and 12% fat.  I noticed that after 6 months of this food that his coat was dry and breakig off so I changed him back to the Royal Canine.  After 1 week on the Royal Canine his breath is terrible again.  I have to conclude that it is the food change and I am wondering if it is the higher protien and fat level.  If it is then does this give an indication of a bigger problem.  I am concerned about liver and kidney toxicity. Any information you can give me would be greatly appreciated.

Answer
I don't have near the confidence in Royal Canin and other specialty, premium chows many do, but I still don't think it would harm your dog.  Those levels of fat and protein are common, and the dog should be able to burn off the excesses as energy.  The Pro Plan I feed contains contains some what less, 26% protein and 16% fat.  Not only do my dogs do fine on it, but so do thousands of others I see that are eating it.  The breath problem could be as simple as that the extra fat, and perhaps smaller size, makes it so attractive, it could mean he is bolting it down without the teeth cleaning chewing that a dry chow should give.

Most dogs will thrive on most chows.  Your Yorkie may be one of them that needs a little extra fatty acids in its diet.  You could go back to the Nutro, and add a little more.  The cheapest and easiest thing is just to add a tea spoon or less of liquid cooking oil a day.  Most of them are just corn or soybean oil, and are excellent sources for the linoleic acid dogs require.  I am skeptical of the fish oil capsules since fish oil doesn't have any linoleic acid in it.  Another alternative is to check the labels of other brands of dog chow and look for something with fat and protein levels between the Nutro and RC.  I would stick to a chicken based one.  No matter what you feed, some dogs will become allergic to it eventually.  The more different proteins a dog is exposed to when young, the harder it is to work around it if it develops allergies later.  Dogs commonly become allergic to corn and chicken, because dogs commonly eat corn and chicken.