Dogs and cats are carnivores. They are meant to eat a high quality protein diet with high moisture content of about 70%, not the typical 10-15% moisture that we see on dry food (kibble) labels. The high moisture content is necessary to help prevent organ dysfunction, including kidney failure.  This is especially important for cats who do not typically drink as much as dogs, but require high moisture content in their diets.  Pets who are fed a dry food diet are typically found to be in a state of chronic, mild dehydration that can put a lot of stress on their organs.