From this months issue of whole Dog Journal.
“You may have been told that it’s bad to switch foods, or you may have had a bad experience when your dog ate something different and erupted in gas or diarrhea. With most dogs the more you change foods, the more robust and capable their digestion becomes. We suggest switching foods every few months ( or even more frequently; we switch our dogs food with every bag). Switching foods frequently also helps prevent the development of allergies, and helps provide nutritional “balance over time.” If your dog ate the same food for months and years, the nutrient levels – particularly the mineral levels- become literally entrenched in your dogs body. This can be particularly harmful if the food you feed contains excessive or insufficient levels of certain vitamins or minerals.
Finally watch your dog! Let her tell you how the new food works for her. Keep track of what foods you’ve tried ( when the bag is empty, we cut out the ingredients panel and tape it to the calendar). This way you can continue to make adjustments and improvements in her physical condition, skin and coat, and overall energy level.
Hope you will find this as useful as I did. I am sending this to many different groups so you may receive more than once. Feel free to pass on.