No different than humans…is your diarrhea, vomiting, and lethargy always a result of your last meal? No. If there is someone out there, regardless of dog food brand, who has owned a dog that didn’t get diarrhea or have other illnesses throughout their lifetime, they are unbelievably fortunate.
I will say that a great way to give your dog those symptoms is too switch brands of foods to quickly without a slow changeover. if one just switches brands, I would expect diarrhea for sure, and possibly other problems. I’m curious how many people made an abrupt switch to TOTW and then were aghast when their dogs got the squirts. I’m only speculating, but I know many dog owners who have made that mistake with a variety of different brands and have found the same result. Blaming the dog food for each case of GI problems is easy, but it’s probably not accurate most of the time.
I’ve had two dogs on TOTW their entire lives. One is now only 3 but the other lived to be almost 11. They both stayed healthy, athletic, lean, and loved their food. I used the lamb formula but used all of the others (bison, venison, fowl, salmon, etc.) as treats. In fact I mixed some of each together in a large bag and sprinkled some in with every feeding of the lamb formula.
I do have other acquaintances who have had great experience with this brand as well.