Food Intolerance / Insensitivity
Feeding the best food and ingredients is great unless your dog or cat has an intolerance or sensitivity to them. Dogs can experience allergic reactions the same as people. But food intolerance or sensitivity is more common than a food allergy. Food intolerances/sensitivities can manifest in (GI) gastrointestinal issues, chronic itching, gas rumblings, chronic gas, chronic burping, chronic skin, ear and foot infections, especially with the presence of yeast. 
I have found that a small amount of an offending ingredient causes issues. Reactions can be caused by the differing proteins, or oats, millet, quinoa, lentils, barley, salmon oil, herring oil, etc. Food intolerances/sensitivities can manifest in gastrointestinal issues, diarrhea, chronic itching, chronic gas, chronic skin, ear and foot infections, especially with the presence of yeast.
Food allergies reflect a more immediate immunological response whereas food intolerances/sensitivities build up over time with exposure to offending ingredient(s). Rotating foods every two to three months can do more then add to our dog's enjoyment of his food, it may help to avoid the development of particular food sensitivity and food allergies. The greater the length of time and frequency a particular food is consumed the greater likelihood an intolerance/sensitivity can develop over time.
Allergy reactions show up in allergy blood test as antibodies (IgE and IgG). Testing a dog’s saliva for a differing set of antibodies (IgA and IgM) is recommended for testing for the food sensitivity & intolerance. With the NutriScan kit you collect saliva with a small cotton dental rope. You can do this at home or at the vet’s office. Then ship the kit back to Hemopet for testing.
I have used and recommend food sensitivity & intolerance test from NutriScan. I ran two NutriScan tests on my Dalmatian and one test on my shepherd mix. My Dalmatian had reactions to almost everything which required me to change and limit her diet. I ran the second test on my Dalmatian about 10-months after the first test and the numbers were dropping (although far from good) on the foods I had eliminated from her diet. It was very helpful after getting results and eliminating foods from both of my dogs diet. Less gas, less bouts of diarrhea, and overall saw an improvement in well-being. My two dogs always loved to eat grass and we would say that they just liked their salad and that it was normal. But after running a NutriScan food intolerance test on each of them and eliminating several foods from their diet their grass eating reduced about 95%. (after eating grass they were not throwing up).
Generally speaking I look at nutrition as a three leg stool. Ingredients, quality, and balance. Any one of these missing or short throws the whole diet out of balance. For me it is essential to identify and eliminate any food from the diet that can create intolerance. And NutriScan helped eliminate the guesswork with weeks of food trails.