My theory after reading what is available on this question is that problem with grain-free food is caused by following reasons. Those dog food producers wanted to replace grains with beans and legumes to make food 1) free of gluten and low in carbs 2) higher in protein. By doing so they could also reduce meat content, because beans and legumes are high in protein, but cheaper than meat. As a result, they made food with necessary amount of protein and low in carb. But there are 2 problems with beans. First, their protein is not so easily digestible as meat is (itās plant protein and it needs long Gastrointestinal tract to be fully digested, and we know dogs as carnivores have very short GI tract). Second, plant proteins are not so perfect as eggs and meat in amino acid spectrum, less taurine, cysteine, methionine etc). Besides, many beans and legumes contain so called anti nutrients, physical acid and lectins, which reduce absorption and digestion of many important nutrients. Thatās why you should soak beans for a night before cooking or even better sprout them
So, my theory is that this dog food because of high bean/legumes content while having seemingly high protein content, in fact, was deficient in amino acids because bigger proportion of total protein amount came from beans, not meat (itās much cheaper!) and as a result of low bioavailability of this protein and anti nutrients which interfered with absorption of other vitamins or micro elements.
So, DCM in those poor dogs was a result of malnutrition. And poor business strategies. Producers of grain free food were too greedy and couldnāt resist temptation of reducing costs of food replacing meat protein with beans/legumes protein, because, Iām sure, no one checked exact ratio of meat/ bean protein, only total protein content.
